From swody2 at goshenarc.org Fri Sep 1 05:52:58 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 01 Sep 2006 01:52:58 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 010553 SWODY2 SPC AC 010552 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1252 AM CDT FRI SEP 01 2006 VALID 021200Z - 031200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER PATTERN TO REMAIN GENERALLY UNCHANGED ON THE LARGE SCALE THIS PERIOD...WITH STRONGER/MORE ACTIVE FLOW CONFINED TO AREAS WELL N OF THE U.S./CANADA BORDER. MAIN FEATURE OF INTEREST OVER THE CONUS WILL BE A TROUGH OVER THE CENTRAL CONUS/MIDWEST -- COMPRISED OF TWO SMALLER-SCALE CENTERS OF VORTICITY. THE FIRST -- A WEAK UPPER LOW -- IS FORECAST TO MOVE SLOWLY SSEWD ACROSS THE NRN AND CENTRAL HIGH PLAINS...WHILE THE SECOND MOVES NWD ACROSS THE OH VALLEY AND INTO THE GREAT LAKES REGION. AT THE SURFACE...A FRONT IS FORECAST TO MOVE SLOWLY SWD ACROSS TX/THE GULF COAST REGION...AHEAD OF LARGE HIGH PRESSURE OVER THE PLAINS. THOUGH A MOIST AIRMASS IS FORECAST ALONG AND S OF THIS BOUNDARY...WEAK LAPSE RATES WILL LIMIT POTENTIAL FOR DESTABILIZATION...WHILE WEAK WIND FIELD FURTHER LIMITS ANY THREAT FOR STRONG/SEVERE CONVECTION. NAM HINTS AT SOME POTENTIAL FOR A FEW STRONGER STORMS ACROSS THE CAROLINAS DURING THE AFTERNOON INVOF NERN EXTENSION OF AFOREMENTIONED COLD FRONT. HOWEVER...SHEAR AND INSTABILITY SHOULD REMAIN MARGINAL FOR SUPPORTING-+ WELL-ORGANIZED CONVECTION. FURTHER...QUESTIONS REGARDING THE ACTUAL SURFACE PATTERN ACROSS THE ERN U.S. IN THE WAKE OF ERNESTO RENDER THE CONVECTIVE FORECAST DIFFICULT ACROSS THIS REGION -- AND THUS WILL NOT INTRODUCE ANY SEVERE PROBABILITIES ATTM. ..GOSS.. 09/01/2006  From swody2 at goshenarc.org Fri Sep 1 17:22:30 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 01 Sep 2006 13:22:30 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 011723 SWODY2 SPC AC 011722 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1222 PM CDT FRI SEP 01 2006 VALID 021200Z - 031200Z ...NO SVR TSTM AREAS FORECAST... ...ARIZONA... SFC DEWPOINTS SHOULD REMAIN IN THE UPPER 50S TO NEAR 60 F ACROSS MUCH OF THE ARIZONA DESERTS SATURDAY. THIS SHOULD ALLOW FOR SOME DESTABILIZATION ACROSS THE REGION BY SATURDAY AFTERNOON. THUNDERSTORMS WILL LIKELY DEVELOP ON THE MOGOLLON RIM AND CONVECTIVE COVERAGE SHOULD INCREASE BY EARLY EVENING. FORECAST SOUNDINGS EARLY SATURDAY EVENING ACROSS THE REGION SHOW VERY STEEP LAPSE RATES AND STRONG ENOUGH VERTICAL SHEAR FOR ISOLATED STRONG WIND GUSTS WITH THE MORE ORGANIZED MULTICELL THUNDERSTORMS. ...MID-ATLANTIC... THE REMNANTS OF ERNESTO ARE FORECAST TO MOVE NWD ACROSS THE MID-ATLANTIC REGION TONIGHT INTO SATURDAY. ALTHOUGH THE SYSTEM IS LIKELY TO CONTINUE WEAKENING WITH TIME...SOME HEAVY RAINBANDS MAY STILL EXIST WITH ISOLATED THUNDERSTORM ACTIVITY POSSIBLE ON SATURDAY ACROSS THE MID-ATLANTIC. FORECAST SOUNDINGS SATURDAY AFTERNOON ACROSS THE REGION SHOW STRONG ENOUGH VERTICAL SHEAR PROFILES FOR ORGANIZED STORMS. HOWEVER...INSTABILITY WILL LIKELY BE TOO WEAK FOR A THREAT OF ROTATING STORMS. ...UPPER MS VALLEY/MID-MO VALLEY... AN UPPER-LEVEL TROUGH OVER THE NRN HIGH PLAINS IS FORECAST TO CLOSE-OFF AND MOVE SEWD INTO THE NRN PLAINS SATURDAY. MODEL FORECASTS ARE CONSISTENT DEVELOPING THUNDERSTORM ACTIVITY ALONG THE LEADING EDGE OF LARGE-SCALE ASCENT ON THE EAST SIDE OF THE SYSTEM. HOWEVER...INSTABILITY IS FORECAST TO BE WEAK SATURDAY AFTERNOON AND A SEVERE THREAT IS NOT ANTICIPATED ACROSS THE REGION. ..BROYLES.. 09/01/2006  From swody2 at goshenarc.org Sat Sep 2 05:51:11 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 02 Sep 2006 01:51:11 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 020552 SWODY2 SPC AC 020551 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 AM CDT SAT SEP 02 2006 VALID 031200Z - 041200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LARGE-SCALE UPPER PATTERN TO CHANGE LITTLE THIS PERIOD...WITH A TROUGH OFF THE PAC NW COAST...A RIDGE OVER THE ROCKIES...A TROUGH IN THE CENTRAL CONUS...AND A RIDGE OVER THE EAST. THE CENTRAL U.S. TROUGH WILL MAKE SOME EWD PROGRESS WITH TIME...WITH EMBEDDED UPPER LOW MOVING SLOWLY EWD ACROSS THE MID MO VALLEY REGION THROUGH THE PERIOD. AT THE SURFACE...MAIN BAROCLINIC ZONE WILL REMAIN FROM THE ATLANTIC COAST STATES SWWD INTO THE SOUTHEAST...AND THEN WSWWD ACROSS THE GULF COAST REGION INTO S TX. WIDESPREAD LOW-LEVEL NLYS WILL PREVAIL ACROSS MUCH OF THE CONUS FROM THE ROCKIES EWD TO THE APPALACHIANS... WITH A CORRESPONDING LACK OF RICH MOISTURE/SIGNIFICANT INSTABILITY. ...MN SWD INTO NRN MO... DESPITE THE LACK OF A HIGH THETA-E BOUNDARY LAYER AIRMASS...MID-LEVEL COLD POOL /-14 TO -18 C/ ASSOCIATED WITH UPPER LOW WILL MOVE SLOWLY EWD INTO THIS REGION. AS A RESULT...MARGINAL INSTABILITY /AOB 500 J/KG MEAN-LAYER CAPE/ IS EXPECTED NEAR AFTERNOON PEAK HEATING. THIS SHOULD SUPPORT INITIATION OF SCATTERED/LOW-TOPPED STORMS DURING THE AFTERNOON...WHICH SHOULD THEN RAPIDLY DIMINISH AFTER SUNSET. THOUGH INSTABILITY WILL REMAIN LIMITED...40 TO 50 KT CYCLONIC MID-LEVEL JET STREAK ACCOMPANYING THE UPPER LOW SHOULD SPREAD ACROSS NRN MO/ERN IA. RESULTING SHEAR COMBINED WITH DEGREE OF INSTABILITY MAY SUPPORT A FEW ORGANIZED/ROTATING STORMS -- WITH ASSOCIATED THREAT FOR HAIL. WILL INTRODUCE 5% SEVERE PROBABILITY THIS FORECAST TO REFLECT THE POSSIBLE THREAT. ..GOSS.. 09/02/2006  From swody2 at goshenarc.org Sat Sep 2 17:17:09 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 02 Sep 2006 13:17:09 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 021717 SWODY2 SPC AC 021716 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1216 PM CDT SAT SEP 02 2006 VALID 031200Z - 041200Z ...NO SVR TSTM AREAS FORECAST... ...SRN MN/SW WI TO NRN MO... MODELS REMAIN CONSISTENT WITH TRACK OF SD CLOSED UPPER LOW TOWARD THE SE...REACHING CENTRAL IA BY 12Z MONDAY. LARGE SCALE ASCENT OF THIS FEATURE WITHIN EXIT REGION OF ACCOMPANYING 50-60 KT WNWLY MID LEVEL JET IS EXPECTED TO AID IN THUNDERSTORM DEVELOPMENT FROM SRN MN INTO NRN MO. ALTHOUGH DEEP LAYER SHEAR SHOULD BE SUFFICIENT FOR ORGANIZED STORMS...WEAK INSTABILITY IS EXPECTED TO LIMIT SEVERE COVERAGE. A FEW LOW-TOPPED STORMS WILL BE CAPABLE OF PRODUCING HAIL GIVEN COLD POCKET /-14 TO -18 C AT 500 MB/. ...LOWER CO RIVER VALLEY... HURRICANE JOHN IS EXPECTED TO WEAKEN TO A TROPICAL STORM TODAY...PER LATEST NHC GUIDANCE...AS THIS SYSTEM TRACKS NWWD ALONG THE BAJA PENINSULA INTO DAY 2 PERIOD. A NWD SURGE OF MOISTURE /SURFACE DEWPOINTS IN THE 60S/ IS EXPECTED TO SPREAD INTO THE LOWER CO RIVER VALLEY AND SRN CA ON SUNDAY CONTRIBUTING TO MODERATE INSTABILITY AS SURFACE TEMPERATURES RISE THROUGH THE 90S SUNDAY AFTERNOON. MID LEVEL WINDS ACROSS AZ TO SRN CA ARE EXPECTED TO BECOME NELY AS JOHN TRACKS NWWD ALONG CENTRAL BAJA PENINSULA. THIS WILL ALLOW STORMS TO DEVELOP SWWD OFF THE HIGHER TERRAIN INTO THE LOWER CO RIVER VALLEY WHERE MODERATE INSTABILITY AND STEEP LOW LEVEL LAPSE RATES SHOULD FAVOR A POTENTIAL FOR STRONG WIND GUSTS. WEAK DEEP LAYER SHEAR WILL LIKELY LIMIT SEVERE COVERAGE. THUS...HAVE ONLY INTRODUCED A 5% SEVERE PROBABILITY. ..PETERS.. 09/02/2006  From swody2 at goshenarc.org Sun Sep 3 06:07:58 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 03 Sep 2006 02:07:58 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 030604 SWODY2 SPC AC 030603 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0103 AM CDT SUN SEP 03 2006 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... AMPLIFICATION OF THE UPPER PATTERN OVER THE CONUS IS FORECAST THIS PERIOD...AS ERN U.S. TROUGH -- AND EMBEDDED UPPER LOW -- DEEPENS AND MOVES SLOWLY EWD ACROSS THE MS VALLEY REGION...ALLOWING AN EXPANSION OF THE WRN U.S. RIDGE. THE MAIN SURFACE BAROCLINIC ZONE WILL REMAIN IN PLACE FROM THE SERN U.S. WSWWD ACROSS THE GULF COAST REGION AND INTO S TX...WITH NLY LOW-LEVEL FLOW PREVAILING FROM THE PLAINS TO THE APPALACHIANS. A FEW STRONG/POSSIBLY SEVERE STORMS MAY FORM AHEAD OF THE UPPER LOW OVER THE UPPER MS VALLEY REGION...AND IN ELY POST-FRONTAL UPSLOPE FLOW REGIME OVER THE HIGH PLAINS OF CO/NERN NM. HOWEVER...WITH HIGHER THETA-E AIRMASS REMAINING ACROSS S TX AND THE GULF COAST REGION...INSTABILITY -- AND THUS CONVECTIVE INTENSITY -- SHOULD REMAIN LIMITED IN MOST AREAS. ...HIGH PLAINS OF CO/NERN NM... SELY POST-FRONTAL UPSLOPE FLOW IS FORECAST ACROSS THE SRN AND INTO THE CENTRAL HIGH PLAINS...WHERE RELATIVELY MEAGER BOUNDARY-LAYER MOISTURE SHOULD RESULT IN VERY MARGINAL INSTABILITY. SOME DIURNAL CONVECTION IS EXPECTED ACROSS THIS REGION...THOUGH OVERALL STORM INTENSITY SHOULD REMAIN LIMITED DUE TO THERMODYNAMIC DEFICIENCY. IF SUFFICIENT DESTABILIZATION COULD OCCUR...40 KT NWLY MID-LEVEL FLOW ABOVE LOW-LEVEL SELYS WOULD RESULT IN SHEAR SUPPORTIVE OF ORGANIZED STORMS. THEREFORE...WILL INITIATE 5% CONDITIONAL SEVERE PROBABILITY ACROSS THIS REGION. ANY THREAT WOULD RAPIDLY DIMINISH THROUGH THE EVENING. ...ERN IA/NRN IL/SRN WI... DIURNAL STORM DEVELOPMENT IS ANTICIPATED ACROSS ERN IA AND INTO NRN IL/SRN WI...NEAR UPPER LOW AND ASSOCIATED COLD POOL WHERE MARGINAL AFTERNOON DESTABILIZATION IS EXPECTED. WITH COMPACT 35 KT MID-LEVEL JET STREAK FORECAST ON SERN FRINGE OF UPPER LOW...SHEAR SUPPORTIVE OF ORGANIZED/LOW-TOPPED STORMS SHOULD EXIST. THEREFORE...WILL MAINTAIN A 5% SEVERE PROBABILITY ACROSS THIS REGION FOR STRONGER AFTERNOON CONVECTION. ..GOSS.. 09/03/2006  From swody2 at goshenarc.org Sun Sep 3 17:08:11 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 03 Sep 2006 13:08:11 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 031708 SWODY2 SPC AC 031707 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1207 PM CDT SUN SEP 03 2006 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...HIGH PLAINS OF CO/NERN NM... WATER VAPOR IMAGERY CURRENTLY SHOWED A COUPLE OF SHORT WAVE TROUGHS MOVING SSWWD ACROSS WY AND ERN MT. MODELS SUGGEST THE MT IMPULSE WILL TRACK SSEWD ACROSS CO ON MONDAY. STEEP LOW AND MID LEVEL LAPSE RATES COMBINED WITH SURFACE HEATING ARE EXPECTED TO OFFSET MODEST LOW LEVEL MOISTURE AND ALLOW FOR AT LEAST MARGINAL INSTABILITY /MLCAPE 500-1000 J/KG/ TO DEVELOP MONDAY AFTERNOON. OROGRAPHIC FORCING COMBINED WITH ASCENT AHEAD OF MT SHORT WAVE TROUGH SHOULD SUPPORT THUNDERSTORM DEVELOPMENT MAINLY ACROSS THE HIGHER TERRAIN OF SRN CO AND NRN-NERN NM...WITH ACTIVITY MOVING SSEWD INTO THE ADJACENT HIGH PLAINS. THE POTENTIAL WILL EXIST FOR STORMS TO BECOME ORGANIZED AS NWLY MID LEVEL WINDS STRENGTHEN TO AROUND 40 KT BY LATE MONDAY AFTERNOON ATOP ESELY LOW LEVEL WINDS...RESULTING IN 30-40 KT OF DEEP LAYER SHEAR. HOWEVER...OVERALL COVERAGE OF THE SEVERE THREAT SHOULD REMAIN BELOW A CATEGORICAL RISK...GIVEN MARGINAL INSTABILITY. THUS...THIS OUTLOOK WILL MAINTAIN A 5% SEVERE PROBABILITY. ...PART OF UPPER MS VALLEY AND MIDWEST... CLOSED UPPER LOW...CURRENTLY LOCATED OVER THE MID MO RIVER VALLEY PER WATER VAPOR IMAGERY...WILL CONTINUE TO TRACK SLOWLY SEWD FROM IA INTO IL DURING DAY 2 PERIOD. MARGINAL INSTABILITY ACROSS THIS REGION IS EXPECTED TO SUPPORT ANOTHER DAY OF DIURNAL THUNDERSTORM DEVELOPMENT NEAR UPPER LOW AND ASSOCIATED MID LEVEL COLD POCKET /-14 TO -18 C AT 500 MB/. STRONGER MID LEVEL FLOW ALONG THE SRN AND NRN PERIPHERIES OF THE UPPER LOW /MO INTO IL AND NRN WI INTO MN/ INDICATES A POTENTIAL FOR STORM ORGANIZATION ACROSS THESE AREAS... BUT LIMITED INSTABILITY SHOULD PRECLUDE A GREATER COVERAGE OF SEVERE STORMS. ..PETERS.. 09/03/2006  From swody2 at goshenarc.org Mon Sep 4 06:06:53 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Mon, 04 Sep 2006 02:06:53 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 040605 SWODY2 SPC AC 040604 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0104 AM CDT MON SEP 04 2006 VALID 051200Z - 061200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LARGE UPPER RIDGE WILL REMAIN OVER THE WRN CONUS THIS PERIOD...WHILE ERN U.S. TROUGH DIGS SEWD INTO THE OH AND TN VALLEYS/SOUTHEAST STATES. THE DIGGING TROUGH SHOULD DRIVE WEAK CYCLOGENESIS ACROSS GA/THE CAROLINAS ALONG REMNANT BAROCLINIC ZONE. ...THE SOUTHEAST INTO THE CAROLINAS... MOIST BOUNDARY LAYER IS FORECAST AHEAD OF BAROCLINIC ZONE OVER THIS REGION...THOUGH WEAK LAPSE RATES SHOULD LIMIT POTENTIAL FOR DESTABILIZATION. NONETHELESS...LOW-LEVEL UVV ASSOCIATED WITH WEAK CYCLOGENESIS SHOULD RESULT IN STORM DEVELOPMENT FROM GA NEWD INTO THE CAROLINAS BY AFTERNOON...AS UPPER TROUGH APPROACHES. THOUGH OVERALL SEVERE THREAT SHOULD REMAIN LIMITED DUE TO WEAK INSTABILITY...35 KT SWLY MID-LEVEL FLOW MAY AID IN THE DEVELOPMENT OF A FEW STRONGER/SUSTAINED STORMS...AND THEREFORE WILL EXPAND THE 5% SEVERE PROBABILITY E OF THE APPALACHIANS INTO THE CAROLINAS THIS FORECAST. ...MIDDLE OH/TN VALLEYS... MARGINAL DIURNAL DESTABILIZATION IS FORECAST ACROSS THE MIDDLE OH VALLEY REGION AS COLD POOL ASSOCIATED WITH UPPER LOW SPREADS SLOWLY EWD. SCATTERED THUNDERSTORMS WILL LIKELY DEVELOP AHEAD OF UPPER LOW DURING THE AFTERNOON...THOUGH LIMITED DESTABILIZATION SUGGESTS THAT MOST STORMS SHOULD REMAIN WEAK. A FEW STRONGER/WEAKLY-ORGANIZED STORMS -- AIDED BY 35 KT SWLY FLOW AT MID-LEVELS -- MAY DEVELOP ACROSS CENTRAL KY/SRN INDIANA/SWRN OH...ALONG WITH ATTENDANT LOW PROBABILITY SEVERE THREAT. THREAT WILL DIMINISH QUICKLY DURING THE EVENING WITH THE ONSET OF BOUNDARY-LAYER STABILIZATION. ...NERN NM/SERN CO... WEAK DESTABILIZATION ACROSS THE HIGHER TERRAIN OF SERN CO AND ADJACENT NERN NM BENEATH 30 KT NLY FLOW ALOFT MAY RESULT IN A LOW-END SEVERE THREAT AS A FEW WEAKLY-ORGANIZED STORMS DEVELOP DURING THE AFTERNOON. OVERALL THREAT SHOULD REMAIN LOW DUE TO LIMITED INSTABILITY. ..GOSS.. 09/04/2006  From swody2 at goshenarc.org Mon Sep 4 17:31:30 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Mon, 04 Sep 2006 13:31:30 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 041731 SWODY2 SPC AC 041730 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT MON SEP 04 2006 VALID 051200Z - 061200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER LOW CURRENTLY OVER THE UPPER MS VALLEY IS FORECAST TO AMPLIFY SEWD INTO THE OH AND TN VALLEY REGION TUESDAY. AS THIS OCCURS A WEAK SURFACE LOW IS FORECAST TO DEVELOP AND LIFT NEWD ALONG PRE-EXISTING FRONT FROM GA INTO THE CAROLINAS. FARTHER WEST...HIGH PRESSURE WILL CONTINUE TO SETTLE SWD INTO THE PLAINS IN WAKE OF THIS FEATURE. ...GA THROUGH THE CAROLINAS... A MOIST BOUNDARY LAYER WITH DEWPOINTS IN THE LOWER 70S WILL PERSIST IN THE PRE-FRONTAL WARM SECTOR FROM CNTRL/SRN GA NEWD INTO THE ERN CAROLINAS AND SERN VA. POCKETS OF SURFACE HEATING MAY DEVELOP IN WARM SECTOR DURING THE DAY...BUT CAPE IS EXPECTED TO REMAIN GENERALLY AOB 1000 J/KG OWING TO WEAK LAPSE RATES. SOME INCREASE IN MIDDLE TO HIGH LEVEL FLOW MAY OCCUR FROM PARTS OF GA INTO THE CAROLINAS AS THE UPPER TROUGH AMPLIFIES INTO THE OH AND TN VALLEY. HOWEVER...SURFACE DEVELOPMENT AND LOW LEVEL WIND FIELDS ARE EXPECTED TO REMAIN WEAK. STORMS MAY INTENSIFY ALONG AND AHEAD OF THE FRONT AS THE BOUNDARY LAYER DESTABILIZES WITH PRIMARY THREAT BEING ISOLATED STRONG WIND GUSTS. MARGINAL THERMODYNAMIC PROFILES AND MODEST WIND FIELDS THROUGH 6 KM SUGGEST OVERALL THREAT SHOULD REMAIN LIMITED. ...OH VALLEY... SCATTERED STORMS MAY ONCE AGAIN DEVELOP WITHIN ZONE OF ASCENT NEAR VORT MAX CENTER OVER PARTS OF THE OH VALLEY. TEMPERATURES NEAR THE UPPER LOW CENTER ARE NOT FORECAST TO BE AS COOL AS IN PREVIOUS DAYS WITH -15 TO -16 EXPECTED. WHERE BOUNDARY LAYER WARMING CAN OCCUR... MLCAPE AROUND 500 J/KG WILL BE POSSIBLE. A MARGINAL THREAT OF HAIL WILL EXIST WITH THE STRONGER STORMS THROUGH EARLY EVENING...BUT OVERALL THREAT DOES NOT APPEAR TO WARRANT MORE THAN 5% HAIL PROBABILITIES AT THIS TIME. ...SERN CO THROUGH NERN NM... POTENTIAL WILL EXIST FOR STORMS TO DEVELOP OVER THE HIGHER TERRAIN AS THE ATMOSPHERE DESTABILIZES. RESIDUAL LOW LEVEL MOISTURE WITH DEWPOINTS IN THE UPPER 40S NEAR THE FRONT RANGE AND STEEP MID LEVEL LAPSE RATES WILL CONTRIBUTE TO MLCAPE AROUND 500 J/KG. NLY 30 KT WINDS AT 6 KM ABOVE LIGHT SELY LOW LEVEL FLOW WILL CONTRIBUTE TO 0-6 KM SHEAR AT LEAST MARGINALLY SUFFICIENT FOR MID LEVEL UPDRAFT ROTATION. THIS ALONG WITH STEEP MID LEVEL LAPSE RATES SUGGEST HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS. GENERALLY NLY FLOW IN THE 3-8 KM LAYER SUGGESTS STORMS WILL PROBABLY NOT ADVANCE TOO FAR E OF THE HIGHER TERRAIN. ..DIAL.. 09/04/2006  From swody2 at goshenarc.org Tue Sep 5 06:08:13 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 05 Sep 2006 02:08:13 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 050606 SWODY2 SPC AC 050605 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0105 AM CDT TUE SEP 05 2006 VALID 061200Z - 071200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... MID-LEVEL SHORT-WAVE TROUGH SHOULD MOVE ENEWD FROM THE UPPER OH VALLEY ACROSS NEW ENGLAND...BUT LARGE-SCALE MEAN TROUGH WILL REMAIN ACROSS THE ERN 2/3 OF THE CONUS THROUGH THE PERIOD. AT THE SURFACE...COLD FRONT SHOULD LINGER ALONG THE ATLANTIC COASTAL REGION THROUGH MUCH OF THE PERIOD. ...SERN VA SSWWD INTO FAR SERN GA... WEAK LAPSE RATES BUT VERY MOIST BOUNDARY LAYER SHOULD RESULT IN MARGINAL DESTABILIZATION AHEAD OF COLD FRONT. STORMS WILL LIKELY BE ONGOING ACROSS THIS REGION AT THE START OF THE PERIOD...WITH SOME INCREASE IN INTENSITY POSSIBLE AS LOCAL HEATING HELPS BOOST INSTABILITY IN SOME AREAS. THOUGH WEAK LAPSE RATES SUGGEST LITTLE HAIL THREAT...FLOW INCREASING WITH HEIGHT TO 40 TO 50 KT FROM THE SSW AT MID-LEVELS SHOULD PROVIDE SHEAR SUFFICIENT FOR LOCALLY STRONG WIND GUSTS -- AND PERHAPS EVEN A TORNADO OR TWO GIVEN VERY MOIST BOUNDARY-LAYER AIRMASS. ...CENTRAL AND SRN HIGH PLAINS... MARGINAL BOUNDARY LAYER MOISTURE BUT STEEP MID-LEVEL LAPSE RATES AND DAYTIME HEATING SHOULD RESULT IN MARGINAL DESTABILIZATION OVER THE CENTRAL AND SRN HIGH PLAINS. THOUGH OVERALL LACK OF LOW-LEVEL FORCING SUGGESTS THAT WEAK CAPPING SHOULD INHIBIT STORMS FOR MUCH OF THE DAY...SCATTERED TO ISOLATED STORMS SHOULD DEVELOP NEAR PEAK HEATING ACROSS THIS REGION. LOW-LEVEL SLYS BENEATH 20 KT MID-LEVEL NLYS MAY YIELD SHEAR SUFFICIENT FOR A FEW ORGANIZED STORMS -- AND ASSOCIATED HAIL/WIND THREAT. ANY SEVERE POTENTIAL SHOULD BE CONFINED TO THE PERIOD AROUND PEAK HEATING...WITH RAPID STORM WEAKENING ANTICIPATED AFTER SUNSET. ..GOSS.. 09/05/2006  From swody2 at goshenarc.org Tue Sep 5 17:29:10 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 05 Sep 2006 13:29:10 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 051729 SWODY2 SPC AC 051728 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1228 PM CDT TUE SEP 05 2006 VALID 061200Z - 071200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER TROUGH NOW OVER THE MIDWEST SHOULD EJECT NEWD INTO THE NERN STATES WEDNESDAY. CYCLOGENESIS IS FORECAST OFF THE MID ATLANTIC COAST LATE TONIGHT INTO EARLY WEDNESDAY IN ADVANCE OF THIS FEATURE. AS THIS LOW LIFTS NWD DURING THE DAY...TRAILING COLD FRONT WILL MOVE OFF THE MID ATLANTIC SEABOARD BY EARLY WEDNESDAY AND OFF THE COASTAL CAROLINAS LATER IN THE DAY. FARTHER WEST...A BROAD FETCH OF NLY FLOW ALOFT WILL PERSIST OVER MUCH OF THE CNTRL U.S. BETWEEN THE UPPER LOW IN THE EAST AND AN UPPER LEVEL RIDGE ALONG THE WEST COAST. ...S CNTRL AND SERN CO THROUGH NERN NM... RESIDUAL LOW LEVEL MOISTURE WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S WILL PERSIST OVER THE CNTRL AND SRN HIGH PLAINS BENEATH STEEP LAPSE RATES. MLCAPE FROM 1000 TO 1500 J/KG WILL BE POSSIBLE AS THE BOUNDARY LAYER WARMS DURING THE AFTERNOON. POTENTIAL WILL EXIST FOR WEAK UPPER LEVEL IMPULSES TO MOVE SWD AND ENHANCE ASCENT....AND A FEW STORMS WILL BE POSSIBLE OVER THE HIGHER TERRAIN AS THE ATMOSPHERE DESTABILIZES. STORMS WILL SUBSEQUENTLY SPREAD SSEWD INTO THE HIGH PLAINS. LIGHT SLY BOUNDARY LAYER FLOW ALONG WRN PERIPHERY OF PLAINS SURFACE RIDGE BENEATH 20 TO 25 KT NLY FLOW ALOFT WILL CONTRIBUTE TO 0-6 KM SHEAR AROUND 30 KT. PRIMARY THREATS WILL BE ISOLATED HAIL AND STRONG WIND GUSTS THROUGH EARLY EVENING. ...CAROLINA COASTS... SCATTERED CONVECTION WILL LIKELY BE ONGOING ALONG AND AHEAD OF THE FRONT OVER THE ERN CAROLINAS WEDNESDAY MORNING. WITH STRONGER LOW LEVEL WIND FIELDS EXPECTED TO REMAIN OFFSHORE AND PRESENCE OF WIDESPREAD PRE-FRONTAL CLOUDS...ANY SEVERE THREAT APPEARS MINIMAL. ..DIAL.. 09/05/2006  From swody2 at goshenarc.org Fri Sep 8 05:33:52 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 08 Sep 2006 01:33:52 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 080535 SWODY2 SPC AC 080534 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1234 AM CDT FRI SEP 08 2006 VALID 091200Z - 101200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... SPLIT FLOW...LARGE-SCALE PATTERN IS FORECAST DURING THE DAY TWO PERIOD...CHARACTERIZED BY OMEGA BLOCK ACROSS CANADA AND A WEAKER SRN BRANCH FROM THE GREAT BASIN EWD TO INCREASINGLY CONFLUENT REGION OVER THE OH VALLEY INTO THE NERN STATES. IN THE LOW-LEVELS...PRIMARY FEATURE WILL BE COLD FRONT WHICH WILL PUSH SEWD THROUGH NEW ENGLAND AND THE OH VALLEY. THIS BOUNDARY WILL EXTEND WWD TO LOW PRESSURE AREA DEVELOPING EWD ACROSS KS. ...NEW ENGLAND INTO THE UPPER OH VALLEY... CURRENT SURFACE OBSERVATIONS AND MODEL FORECASTS SUGGEST THAT BOUNDARY LAYER WILL NOT BE PARTICULARLY MOIST AHEAD OF SURFACE FRONT WITH DEWPOINTS LIKELY IN THE 50S TO PERHAPS LOWER 60S. HOWEVER...DAYTIME HEATING COUPLED WITH HEIGHT FALLS/DYNAMIC COOLING AHEAD OF SHORT WAVE TROUGHING DIGGING SEWD THROUGH QUEBEC SHOULD SUPPORT SOME AIR MASS DESTABILIZATION SATURDAY WITH MLCAPES INCREASING TO 500-1000 J/KG AT SOME LOCATIONS. WEAK CAPPING IN CONJUNCTION WITH FRONTAL CONVERGENCE AND INCREASED LARGE-SCALE FORCING FOR ASCENT AHEAD OF UPPER TROUGH WILL ALL CONTRIBUTE TO AN INCREASE IN TSTM COVERAGE THROUGH THE AFTERNOON FROM NRN/CNTRL NEW ENGLAND SWWD THROUGH NY INTO NRN AND CNTRL PARTS OF OH...IND AND IL. FORECAST SOUNDINGS INDICATE THE STRONGEST MID-LEVEL FLOW AND RESULTANT DEEP LAYER SHEAR /30-35 KTS IN THE LOWEST 6 KM AGL/ ACROSS NEW ENGLAND INTO NY...IN CLOSEST PROXIMITY TO MID/UPPER-LEVEL JET STREAKS OVER ERN QUEBEC INTO THE GULF OF ST. LAWRENCE. GIVEN THE MODEST INSTABILITY AND VERTICAL SHEAR...POTENTIAL WILL EXIST FOR A FEW ORGANIZED STORMS WITH A THREAT OF LOCALLY DAMAGING WINDS AND PERHAPS SOME MARGINALLY SEVERE HAIL. ...CNTRL/SRN PLAINS... FAIRLY WIDESPREAD CONVECTIVE DEVELOPMENT IS ANTICIPATED THROUGH THE PERIOD AHEAD OF SRN BRANCH SHORT WAVE TROUGH WHICH WILL SLOWLY SHIFT EWD THROUGH THE CNTRL PLAINS. MODEL GUIDANCE /IN PARTICULAR THE GFS AND SHORT-RANGE ENSEMBLE MEAN SOLUTIONS/ SUGGEST THAT SOME AIR MASS DESTABILIZATION WILL OCCUR SATURDAY AFTERNOON FROM VICINITY OF SURFACE LOW OVER WRN/CNTRL KS SWD ALONG WEAK DRY LINE OR LEE TROUGH INTO WRN TX/WRN OK. GIVEN THE RELATIVELY WEAK VERTICAL SHEAR FORECAST...AND MODEL VARIABILITY IN THE EVOLUTION OF THIS SHORT WAVE TROUGH AND ASSOCIATED CLOUDS/PRECIPITATION...NO SEVERE PROBABILITIES WILL BE INCLUDED ATTM. ...WRN MT/ERN ID... ISOLATED TSTMS WILL BE POSSIBLE AHEAD OF PACIFIC COLD FRONT SATURDAY AFTERNOON INTO EVENING ALONG SRN FRINGE OF STRONG SHORT WAVE TROUGH LIFTING NEWD THROUGH BRITISH COLUMBIA INTO ALBERTA. BOTH VERTICAL SHEAR AND INSTABILITY ARE FORECAST TO BE MARGINAL...THOUGH THE PRESENCE OF STEEP LOW-LEVEL LAPSE RATES MAY SUPPORT A FEW STRONG DOWNBURSTS WITH THE STRONGEST STORMS. ..MEAD.. 09/08/2006  From swody2 at goshenarc.org Fri Sep 8 17:30:35 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 08 Sep 2006 13:30:35 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 081733 SWODY2 SPC AC 081730 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT FRI SEP 08 2006 VALID 091200Z - 101200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... A SHORTWAVE TROUGH WILL AMPLIFY SEWD INTO THE GREAT LAKES AND NERN STATES SATURDAY. THIS WILL RESULT IN A COLD FRONT CURRENTLY FROM SERN CANADA SWWD INTO THE GREAT LAKES CONTINUING SEWD INTO THE NERN U.S. AND OH VALLEY. SWRN PORTION OF THIS BOUNDARY WILL LIKELY SLOW OR STALL AS A SHORTWAVE TROUGH NOW OVER THE GREAT BASIN ADVANCES EWD INTO THE CNTRL HIGH PLAINS. ...NERN STATES AND OH VALLEY... SURFACE HEATING AHEAD OF COLD FRONT AND LOW LEVEL DEWPOINTS IN THE 50S WILL CONTRIBUTE TO MODERATE INSTABILITY SATURDAY FROM PORTIONS OF THE NERN U.S. INTO THE OH VALLEY. HOWEVER...MLCAPE SHOULD REMAIN GENERALLY BELOW 1200 J/KG OWING TO MODEST LOW LEVEL MOISTURE AND 700-500 MB LAPSE RATES. STORMS WILL LIKELY REDEVELOP ALONG THE FRONT BY LATE MORNING OR EARLY AFTERNOON AND SUBSEQUENTLY SPREAD SEWD. STRONGER WIND PROFILES WILL REMAIN IN THE POST FRONTAL ENVIRONMENT IN ASSOCIATION WITH SEWD ADVANCING SHORTWAVE TROUGH. WIND PROFILES IN VICINITY OF FRONT WILL REMAIN UNIDIRECTIONAL WLY WITH 25 TO 30KT IN THE 850 TO 300 MB LAYER AND MODEST VERTICAL SHEAR. THIS SUGGEST STORM MODE SHOULD REMAIN MULTICELLULAR...BUT WITH SOME STORMS EVOLVING INTO LINE SEGMENTS OR CLUSTERS AS THEY MOVE SEWD. ISOLATED DAMAGING WIND GUSTS AND HAIL WILL BE THE MAIN THREATS. THIS AREA WILL BE MONITORED FOR A POSSIBLE UPGRADE TO SLIGHT RISK IN DAY 1 OUTLOOKS. ...CNTRL PLAINS... CONVECTION WILL INCREASE WITHIN ZONE OF WARM ADVECTION AND LARGE SCALE AHEAD OF EWD ADVANCING SHORTWAVE TROUGH. WEAK CYCLOGENESIS AND A 30 TO 35 KT SLY LOW LEVEL JET ARE FORECAST IN ASSOCIATION WITH THIS FEATURE ACROSS KS. THIS WILL ENHANCE ISENTROPIC ASCENT N OF SWD ADVANCING FRONT FROM NRN KS INTO NEB WHERE PRECIPITATION SHOULD BE MORE WIDESPREAD BUT INSTABILITY MORE LIMITED. BEST CHANCE FOR SOME DESTABILIZATION WILL EXIST S OF FRONT WHERE POCKETS OF SURFACE HEATING MAY DEVELOP. HOWEVER...CAPE WILL BE LIMITED BY MODEST LAPSE RATES AND LOW LEVEL MOISTURE. LOW LEVEL WIND PROFILES ASSOCIATED WITH LOW LEVEL JET AND BACKED FLOW E OF SURFACE LOW WILL CONTRIBUTE TO HODOGRAPHS FAVORABLE FOR UPDRAFT ROTATION OVER PORTIONS OF CNTRL OR N CNTRL KS. HOWEVER...THE BEST LOW LEVEL SHEAR WILL MOST LIKELY REMAIN IN THE CLOUDY...COOLER AIR. THIS ALONG WITH MODEST INSTABILITY AND LAPSE RATES IN WARM SECTOR SUGGEST SEVERE THREAT SHOULD REMAIN LOW. ..DIAL.. 09/08/2006  From swody2 at goshenarc.org Sat Sep 9 05:46:59 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 09 Sep 2006 01:46:59 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 090549 SWODY2 SPC AC 090548 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1248 AM CDT SAT SEP 09 2006 VALID 101200Z - 111200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LATEST MODEL GUIDANCE SHOWS A LARGE DEGREE OF VARIABILITY IN EVOLUTION OF MID/UPPER-LEVEL CIRCULATION EMBEDDED WITHIN A WEAK SUB-TROPICAL BRANCH OF WESTERLIES OVER THE CNTRL/SRN PLAINS. THE GFS TAKES THIS FEATURE E INTO THE LOWER MO VALLEY...WITH THE NAM/WRF THE FARTHEST S AND THE ECMWF INDICATING LITTLE MOVEMENT THROUGH THE PERIOD. SIMILARLY...DIFFERENCES EXIST IN LOCATION AND TRACK OF ATTENDANT SURFACE LOW AND SURFACE FRONT...WITH LOW SEVERE PROBABILITIES ASSIGNED TO ROUGHLY A MEAN COLD FRONTAL POSITION AT THE TIME OF PEAK HEATING. ...CNTRL/SRN PLAINS... GIVEN THESE DIFFERENCES...CONSIDERABLE UNCERTAINTY EXISTS IN THE INITIATION AND EVOLUTION OF DIURNAL TSTM DEVELOPMENT SUNDAY AFTERNOON AND EVENING. IT DOES APPEAR THAT FAIRLY WIDESPREAD CLOUDS AND PRECIPITATION WILL LIMIT AIR MASS DESTABILIZATION AHEAD OF SURFACE LOW AND COLD FRONT OVER KS. FARTHER TO THE S...DEWPOINTS IN MID 50S TO LOWER 60S COUPLED WITH ANTICIPATED STRONGER DIABATIC HEATING SHOULD CONTRIBUTE TO THE DEVELOPMENT OF MODERATE AFTERNOON INSTABILITY AHEAD OF FRONT FROM PORTIONS OF THE TX PNHDL AND S PLAINS EWD INTO WRN AND PERHAPS CNTRL OK WITH MLCAPES OF 1000-1500 J/KG. TSTMS ARE EXPECTED TO BECOME INCREASINGLY LIKELY BY AFTERNOON AS FRONT ENCOUNTERS THIS STRONGER INSTABILITY. THOUGH AMBIENT WIND FIELDS WILL NOT BE PARTICULARLY STRONG...FORECAST SOUNDINGS INDICATE PRONOUNCED VEERING THROUGH THE LOWEST 3 KM AGL WITH 30-35 KTS OF EFFECTIVE BULK SHEAR. THIS COMBINATION OF MODEST INSTABILITY AND SHEAR SHOULD SUPPORT AT LEAST A FEW ORGANIZED STORMS CAPABLE OF LOCALLY STRONG WIND GUSTS AND SEVERE HAIL THROUGH THE AFTERNOON AND EVENING HOURS. ..MEAD.. 09/09/2006  From swody2 at goshenarc.org Sat Sep 9 17:17:44 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 09 Sep 2006 13:17:44 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 091720 SWODY2 SPC AC 091719 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1219 PM CDT SAT SEP 09 2006 VALID 101200Z - 111200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... ALTHOUGH THE LATEST MODEL RUNS ARE SIMILAR IN DEPICTING A BROAD TROUGH OVER THE CENTRAL PORTIONS OF THE COUNTRY ON SUNDAY...THE GFS HAS A MORE PRONOUNCED UPPER TROUGH AXIS AND IS FURTHER EWD WITH THE SYSTEM THAN THE NAM. WILL TREND TOWARD THE GFS SINCE THE NAM HAS BEEN SPEEDING UP THE MOTION OF THE SYSTEM THE PAST FEW RUNS. THUS...EXPECT WEAK SURFACE LOW...ASSOCIATED WITH UPPER TROUGH...TO BE LOCATED IN NWRN MO BY LATE SUNDAY AFTERNOON WITH A TRAILING COLD FRONT EXTENDING SWWD INTO NERN OK AND THEN WSWWD INTO THE SRN TX PANHANDLE. CONVECTION IS EXPECTED NEAR THIS FRONT AND ALSO ACROSS THE ROCKIES...WHERE MOISTURE WILL REMAIN TRAPPED UNDER A WEAK UPPER RIDGE...AND ALONG THE GULF COAST STATES AS WEAK HIGH LEVEL IMPULSES MOVE EWD ACROSS THE REGION. ...WRN MO/ERN KS SWWD INTO THE TX PANHANDLE... ALTHOUGH CONVECTION IS FORECAST TONIGHT FROM WRN KS SWD INTO THE TX PANHANDLE...THIS CONVECTION SHOULD WEAKEN SUNDAY MORNING AS IT SPREADS EWD INTO A MORE STABLE ENVIRONMENT OVER ERN KS AND CENTRAL OK. HOWEVER...LARGE SCALE LIFTING WITH THE UPPER TROUGH AND FRONTAL CONVERGENCE SHOULD BE ENOUGH FOR SCATTERED THUNDERSTORMS TO REDEVELOP ALONG AND AHEAD OF THE FRONT DURING THE AFTERNOON. THOUGH IT WILL NOT BE PARTICULARLY MOIST IN THE BOUNDARY LAYER...LOWER TO MID 60 DEWPOINTS AND TEMPERATURES WARMING INTO THE 80S SHOULD RESULT IN MLCAPES AROUND 1000 J/KG. WIND FIELDS ARE NOT FORECAST TO BE STRONG...THOUGH VEERING WIND PROFILES IN THE LOWER 3 KM SHOULD SUPPORT EFFECTIVE SHEAR RANGING FROM 25-35 KT. THE AMOUNT OF INSTABILITY AND SHEAR SHOULD SUPPORT AT LEAST A FEW ORGANIZED STORMS FROM WRN MO/ERN KS SWWD INTO THE TX PANHANDLE. RELATIVELY STEEP LASE RATES IN THE LOWER 2-3 KM INDICATE THAT LOCALLY STRONG/SEVERE WIND GUSTS WOULD BE THE MAIN THREAT. ..IMY.. 09/09/2006  From swody2 at goshenarc.org Sun Sep 10 05:20:33 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 10 Sep 2006 01:20:33 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 100522 SWODY2 SPC AC 100521 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 AM CDT SUN SEP 10 2006 VALID 111200Z - 121200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LATEST SHORT-RANGE MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT IN EVOLUTION OF MID/UPPER-LEVEL TROUGH OVER THE MIDWEST INTO UPPER MS VALLEY. THIS FEATURE...CURRENTLY COMPOSED OF SEVERAL SMALLER PERTURBATIONS OVER KS AND NEB...IS FORECAST TO PHASE WITH NRN BRANCH IMPULSES OVER BRITISH COLUMBIA AND SASKATCHEWAN/MANITOBA...EFFECTIVELY FORMING A LARGER-SCALE TROUGH DURING THE DAY TWO PERIOD. IN THE LOW-LEVELS...ATTENDANT SURFACE LOW WILL DEVELOP GENERALLY EWD ACROSS CNTRL MO INTO CNTRL IL WHILE TRAILING COLD FRONT PUSHES SWD INTO THE LOWER MS VALLEY AND CNTRL TX. A WEAK WARM OR STATIONARY FRONT WILL EXTEND EWD FROM THIS LOW ACROSS THE OH VALLEY. ...OH VALLEY INTO OZARK PLATEAU... IT APPEARS CONSIDERABLE CLOUDS AND PRECIPITATION WILL LIKELY PERSIST THROUGH MUCH OF THE PERIOD FROM VICINITY OF SURFACE LOW EWD ALONG WARM FRONT OWING TO STRONG DEEP-LAYER FORCING VIA LOW-LEVEL WAA AND DCVA AHEAD OF EVOLVING UPPER TROUGH. BETTER POTENTIAL FOR AIR MASS DESTABILIZATION WILL LIKELY OCCUR ACROSS PRE-COLD FRONTAL WARM SECTOR --I.E. CNTRL/SRN PARTS OF MO/IL-- WHERE STRONGER DIABATIC HEATING WILL COMBINE WITH DEWPOINTS IN THE 60S TO SUPPORT MLCAPES OF 1000-1500 J/KG. EXPECT TSTMS TO INCREASE IN COVERAGE AND INTENSITY THROUGH THE AFTERNOON AS FORCING ASSOCIATED WITH UPPER TROUGH AND SURFACE FRONT ENCOUNTER DESTABILIZING AIR MASS. NEITHER VERTICAL SHEAR NOR MID-LEVEL LAPSE RATES ARE FORECAST TO BE PARTICULARLY STRONG AND THIS SHOULD TEND TO LIMIT UPDRAFT STRENGTH/STORM ORGANIZATION. STILL...THE PRESENCE OF RELATIVELY STEEP LOW-LEVEL LAPSE RATES AND MODEST INSTABILITY MAY SUPPORT A FEW MARGINALLY SEVERE STORMS CAPABLE OF STRONG WINDS AND SOME HAIL. STRONGER LOW AND DEEP-LAYER SHEAR WILL LIKELY EXIST NEAR SURFACE LOW EWD ALONG WARM FRONT. HOWEVER...IT APPEARS THAT INSTABILITY WILL REMAIN QUITE MARGINAL OWING TO THE PERSISTENT CLOUDS/PRECIPITATION. ...SRN PLAINS... DIURNAL STRONG STORMS WILL BE POSSIBLE MONDAY AFTERNOON INTO EVENING BOTH ALONG COLD FRONT AS WELL AS IN POST-FRONTAL UPSLOPE OVER CNTRL/ERN NM WITHIN UNSTABLE AIR MASS WITH MLCAPES OF 500-1500 J/KG. HERE TOO...VERTICAL SHEAR WILL REMAIN RELATIVELY WEAK...WITH THE EXCEPTION BEING OVER CNTRL/ERN NM WHERE BACKED LOW-LEVEL WINDS WILL RESULT IN EFFECTIVE BULK SHEAR APPROACHING 30 KTS. LOCALLY STRONG WIND GUSTS WILL BE POSSIBLE WITH THE MOST INTENSE STORMS OVER THE LOWER ELEVATIONS...WHILE THE THREAT OF MARGINALLY SEVERE HAIL WILL EXIST WITH THE STRONGER CELLS DEVELOPING OVER THE HIGH PLAINS. ..MEAD.. 09/10/2006  From swody2 at goshenarc.org Sun Sep 10 17:24:52 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 10 Sep 2006 13:24:52 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 101726 SWODY2 SPC AC 101726 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1226 PM CDT SUN SEP 10 2006 VALID 111200Z - 121200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE SYNOPTIC PATTERN WILL FEATURE BUILDING HEIGHTS ACROSS MUCH OF WRN CONUS...EXCEPT FOR REGIME OF ZONAL NRN STREAM FLOW ACROSS PACIFIC NW. SHORTWAVE TROUGH NOW ANALYZED OVER SRN ALTA IS FCST TO DIG SSEWD OVER NRN HIGH PLAINS...REACHING CENTRAL HIGH PLAINS BY 12/12Z. DOWNSTREAM...BROAD/WEAK MID/UPPER LEVEL LOW -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY AND PROFILER DATA OVER ERN NEB -- IS EXPECTED TO MOVE SLOWLY EWD ACROSS MID/UPPER MS VALLEY REGION. CONSIDERABLE DISAGREEMENT LINGERS AMONGST LATEST RUNS OF SHORT-RANGE DETERMINISTIC MODELS AND SREFX MEMBERS REGARDING PRECISE LOCATION OF CENTER BY 12/00Z AND THEREAFTER...AS WELL AS ASSOCIATED 60 M INTERVAL HEIGHT LINES AT 500 MB. HOWEVER....MOST PROGGED SCENARIOS AS WELL AS ENSEMBLE CONSENSUS FAVOR DIFFUSE/POSITIVELY-TILTED SHORTWAVE TROUGH EXTENDING SWWD FROM THIS LOW TO SRN HIGH PLAINS AT 12/00Z. AT SFC...WEAK FRONTAL-WAVE LOW -- NOW ANALYZED OVER S-CENTRAL NEB/N-CENTRAL KS -- SHOULD BE POSITIONED EARLY IN PERIOD INVOF NRN MO AND TAKE CYCLONICALLY CURVING TRACK ENEWD/NEWD ACROSS NERN MO/NRN IL. CONSIDERABLE PROGNOSTIC VARIATIONS ALSO EXIST IN STRENGTH/TRACK OF THIS FEATURE...WITH SPECTRAL BEING DEEPEST OUTLIER AND OPERATIONAL ETA/NGM APPROXIMATING WEAKEST EXTENT OF ENSEMBLE SPECTRUM. COLD FRONT SHOULD MOVE SEWD FROM SRN HIGH PLAINS...NRN OK...SERN KS POSITION AT 11/12Z TO NEAR AXIS FROM SERN MO...CENTRAL-ERN AR...S-CENTRAL TX BY 12/12Z. ...LOWER OH/MS VALLEY TO NE TX... SCATTERED TO WIDELY SCATTERED TSTMS ARE POSSIBLE BY MID-LATE AFTERNOON...IN WEAKLY CAPPED AIR MASS ALONG/AHEAD OF SFC COLD FRONT. POTENTIAL EXISTS FOR A FEW ORGANIZED MULTICELL CLUSTERS TO DEVELOP...MOST INTENSE CELLS PRODUCING STG-SVR GUSTS AND MRGLLY SVR HAIL. SEVERAL OFFSETTING FACTORS INDICATE AT LEAST MRGL POTENTIAL BUT ALSO PRECLUDE MORE ROBUST SVR PROBABILITIES ATTM. STRONGEST DIRECTIONAL SHEAR WILL EXIST INVOF SFC FRONTAL-WAVE LOW...WHERE SFC WINDS ARE RELATIVELY BACKED. HOWEVER WEAK MIDLEVEL FLOW -- I.E. 15-25 KT AT 500 MB OVER MUCH OF REGION -- WILL PREVENT STRONG DEEP-LAYER SHEAR FROM DEVELOPING. UPPER LEVEL FLOW WILL BE MAXIMIZED BENEATH BROAD SRN STREAM JET BRANCHES OVER OZARKS AND FROM TX ACROSS LOWER MS VALLEY...AIDING IN SHEAR THROUGH CLOUD-BEARING LAYER. WEAK DEEP-LAYER LAPSE RATES WILL LIMIT CAPE...AS WILL POTENTIAL CLOUD COVER AND PRECIP OVER MUCH OF THIS REGION. HOWEVER...POCKETS OF FAVORABLE DIURNAL HEATING MAY YIELD SHALLOW/WELL-MIXED BOUNDARY LAYERS MORE CONDUCIVE TO STG GUSTS...WHILE SFC DEW POINTS GENERALLY IN 60S F SUPPORT MLCAPES IN 1000-2000 J/KG RANGE. ...CENTRAL HIGH PLAINS... ISOLATED TO WIDELY SCATTERED TSTMS ARE POSSIBLE MAINLY FROM MIDAFTERNOON THROUGH EARLY EVENING...AS INSOLATION OPTIMALLY DESTABILIZES BOUNDARY LAYER OVER ERN MOUNTAINS AND ADJACENT FOOTHILLS AND HIGH PLAINS. MOISTURE WILL BE MORE LIMITED WITH NWD EXTENT. HOWEVER...LARGE SCALE ASCENT ASSOCIATED WITH MID-UPPER TROUGH OVER NRN/CENTRAL HIGH PLAINS MAY CONTRIBUTE ENOUGH DESTABILIZATION TO SUPPORT MRGL HAIL/WIND POTENTIAL AS FAR N AS VICINITY CO/WY BORDER. TSTMS SHOULD MOVE GENERALLY SWD WITH ANY SVR THREAT WEAKENING CONSIDERABLY AFTER SUNSET. ..EDWARDS.. 09/10/2006  From swody2 at goshenarc.org Mon Sep 11 05:25:43 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Mon, 11 Sep 2006 01:25:43 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 110527 SWODY2 SPC AC 110526 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1226 AM CDT MON SEP 11 2006 VALID 121200Z - 131200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LOWER OH VALLEY AND MID SOUTH... ...SYNOPSIS... UPPER TROUGH FROM THE UPPER GREAT LAKES INTO THE MIDDLE MS VALLEY WILL AMPLIFY THROUGH THE DAY TWO PERIOD AS EMBEDDED VORTICITY MAXIMA NOW OVER ERN ND/NWRN MN AND ERN MT PHASE AND DIG SEWD TOWARD THE CNTRL AND LOWER MS VALLEY. TO THE SW...VORTICITY MAXIMUM OVER CNTRL/SRN CA IS FORECAST TO BECOME PROGRESSIVELY CUT OFF FROM MEAN FLOW WITH THIS FEATURE REMAINING NEARLY STATIONARY OVER SRN PARTS OF CA/AZ INTO BAJA AND THE NRN GULF OF CA. IN THE LOW-LEVELS...PRIMARY SURFACE LOW ASSOCIATED WITH CNTRL U.S. TROUGH WILL DEVELOP NEWD FROM CNTRL OR SRN IL INTO LOWER MI BY WEDNESDAY MORNING. ATTENDANT COLD FRONT WILL SLOWLY PUSH EWD THROUGH THE CNTRL/SRN MS VALLEY WITH A SECONDARY SURFACE LOW DEVELOPING ON THIS BOUNDARY ALONG THE GULF COAST. ...LOWER OH VALLEY INTO MID SOUTH... LATEST SHORT RANGE MODEL GUIDANCE REMAINS CONSISTENT IN INDICATING THAT THE STRONGEST LARGE-SCALE FORCING FOR ASCENT /12-HR 500 MB HEIGHT FALLS OF 30-60 M/ WILL OCCUR ACROSS SLIGHT RISK AREA LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT...FOCUSING STRONG TO SEVERE STORMS ALONG AND AHEAD OF COLD FRONT. IT APPEARS THAT CLUSTERS OF TSTMS WILL PERSIST THROUGH MUCH OF THE PERIOD AHEAD OF SURFACE FRONT FROM THE OH VALLEY SWD INTO THE MID SOUTH...DRIVEN BY DEEP-LAYER FORCING AHEAD OF DIGGING TROUGH. WHILE MID-LEVEL LAPSE RATES WILL REMAIN RELATIVELY WEAK AND NEAR MOIST ADIABATIC...MOIST BOUNDARY LAYER CONDITIONS AND DIURNAL HEATING WILL CONTRIBUTE TO POCKETS OF MODERATE INSTABILITY WITH MLCAPES APPROACHING 1000-1500 J/KG. THE MOST INTENSE STORM DEVELOPMENT WILL LIKELY OCCUR DURING THE MID TO LATE AFTERNOON HOURS NEAR OR JUST W OF THE MS RIVER AS STRONGER FORCING ASSOCIATED WITH ABOVEMENTIONED...DIGGING VORTICITY MAXIMA BEGIN TO OVERSPREAD FRONTAL ZONE AND WRN EDGE OF INSTABILITY AXIS. INCREASING MID AND UPPER-LEVEL FLOW WILL RESULT IN 30-35 KTS OF EFFECTIVE BULK SHEAR...SUFFICIENT FOR ORGANIZED MULTICELL CLUSTERS AND MARGINAL SUPERCELL/BOW STRUCTURES CAPABLE OF MAINLY DAMAGING WINDS AND SOME SEVERE HAIL. AN ISOLATED TORNADO THREAT MAY EXIST NEAR THE GULF COAST ALONG TRACK OF SECONDARY SURFACE LOW. WHILE DEEP-LAYER SHEAR WILL NOT BE PARTICULARLY STRONG...MODEST LOW-LEVEL SHEAR COUPLED WITH VERY MOIST BOUNDARY LAYER CONDITIONS MAY SUPPORT PERIODIC UPDRAFT ROTATION WITH A THREAT OF A BRIEF TORNADO OR TWO. ...SRN AZ... TSTMS ARE FORECAST TO BECOME INCREASINGLY WIDESPREAD TUESDAY AFTERNOON INTO TUESDAY NIGHT ALONG THE NRN INFLUENCE OF QUASI-STATIONARY UPPER LOW. HERE...STEEP LAPSE RATES WILL COMBINE WITH BOUNDARY LAYER DEWPOINTS IN THE 50S TO SUPPORT MLCAPES OF AROUND 1000 J/KG. FORECAST SOUNDINGS INDICATE ELY LOW-LEVEL FLOW VEERING TO WLY IN THE UPPER TROPOSPHERE WITH GENERALLY 20-25 KTS OF DEEP-LAYER SHEAR. WHILE THIS SHEAR MAY LIMIT THE OVERALL SEVERE WEATHER THREAT...THE STEEP LAPSE RATES AND DEEPLY MIXED BOUNDARY LAYER CONDITIONS INDICATE THE POTENTIAL FOR LOCALLY STRONG WIND GUSTS AND SOME MARGINALLY SEVERE HAIL WITH THE STRONGEST STORMS. ..MEAD.. 09/11/2006  From swody2 at goshenarc.org Wed Sep 13 05:20:30 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 13 Sep 2006 01:20:30 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 130522 SWODY2 SPC AC 130521 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 AM CDT WED SEP 13 2006 VALID 141200Z - 151200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... FURTHER INTENSIFICATION OF LONG WAVE TROUGH WILL OCCUR OVER THE WRN U.S. AS STRONG MID AND UPPER-LEVEL JET STREAKS DIG SEWD TOWARD THE GREAT BASIN FROM THE NERN PACIFIC. AS THIS OCCURS...UPPER LOW NOW OVER SRN AZ/NRN SONORA MEXICO WILL EJECT NEWD INTO THE HIGH PLAINS REGION. IN THE E...CONTINUED WEAKENING OF MID-LEVEL TROUGH WILL OCCUR AS IT APPROACHES THE ATLANTIC COAST. IN THE LOW-LEVELS...LEE CYCLONE OVER NERN WY WILL DEVELOP NEWD INTO WRN OR CNTRL ND WITH ATTENDANT COLD FRONT PUSHING SEWD THROUGH THE PACIFIC NW AND NRN ROCKIES. LEE TROUGH WILL CONCURRENTLY STRENGTHEN OVER THE HIGH PLAINS REGION. MEANWHILE IN THE E...PRIMARY SURFACE LOW OVER SERN GA WILL DEVELOP NEWD ALONG THE SC COAST BEFORE MOVING OFFSHORE WITH ASSOCIATED COLD FRONT PUSHING EWD THROUGH THE PIEDMONT AND COASTAL PLAIN...AND MOST OF THE FL PENINSULA. ...FL PENINSULA NEWD ALONG THE CAROLINA COASTS... TSTMS WILL LIKELY BE ONGOING THURSDAY MORNING IN ADVANCE OF SURFACE LOW AND COLD FRONT WITHIN A MOIST AND WEAKLY CAPPED AIR MASS. VERTICAL SHEAR WILL BE STRONGEST ALONG THE CAROLINA COASTS OWING TO BACKED LOW-LEVEL WINDS AHEAD OF SURFACE LOW...THOUGH THE MARGINAL INSTABILITY SHOULD LIMIT THE POTENTIAL FOR LONGER-LIVED...ORGANIZED UPDRAFTS. FARTHER TO THE S OVER THE CNTRL AND SRN FL PENINSULA... AIR MASS IS EXPECTED TO BECOME MODERATELY UNSTABLE...HOWEVER VERTICAL SHEAR WILL WEAKEN CONSIDERABLY WITH SWD EXTENT. A FEW STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE THROUGH THE MORNING AND AFTERNOON HOURS WITH THE MAIN THREAT BEING LOCALLY STRONG WIND GUSTS. THIS THREAT APPEARS TOO MINIMAL TO WARRANT A SLIGHT RISK. ...FOUR-CORNERS REGION... TSTMS ARE FORECAST TO BECOME INCREASINGLY NUMEROUS THURSDAY AFTERNOON AS LARGE-SCALE FORCING FOR ASCENT IN LEFT EXIT REGION OF APPROACHING UPPER-LEVEL JET STREAK OVERSPREADS REGION. LOW-LEVEL MOISTURE WILL BE MARGINAL THOUGH THE PRESENCE OF RELATIVELY STEEP LOW TO MID-LEVEL LAPSE RATES WILL RESULT IN A MARGINALLY UNSTABLE ENVIRONMENT. THE STRONGEST STORMS WILL BE CAPABLE OF SOME HAIL AND STRONG WIND GUSTS THROUGH THURSDAY EVENING. ..MEAD.. 09/13/2006  From swody2 at goshenarc.org Wed Sep 13 14:04:18 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 13 Sep 2006 10:04:18 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 121738 SWODY2 SPC AC 121737 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1237 PM CDT TUE SEP 12 2006 VALID 131200Z - 141200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE SYNOPTIC PATTERN WILL FEATURE HEIGHT FALLS LATE DAY-2 ACROSS PACIFIC NW AND NRN ROCKIES...ACCOMPANIED BY SEWD SHIFT OF UPPER RIDGING FROM NRN ROCKIES TO SRN/CENTRAL PLAINS. AS THIS OCCURS...DOWNSTREAM UPPER LOW -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER MN/IA BORDER -- IS EXPECTED TO TURN SEWD THEN EWD BETWEEN OH VALLEY AND GREAT LAKES. THIS FEATURE SHOULD EVOLVE TO OPEN-WAVE TROUGH IN PHASE WITH PREVIOUSLY DETACHED SHORTWAVE NOW DIGGING SEWD ACROSS NERN NM AND TX PANHANDLE. BY END OF PERIOD...COMBINED TROUGH SHOULD EXTEND FROM ERN GREAT LAKES SWWD TO CENTRAL GULF COAST. ASSOCIATED SFC LOW -- NOW ANALYZED INVOF IL/WI BORDER -- IS FCST TO MOVE NEWD ACROSS SRN PORTIONS ONT/QUE DAY-2...AS TRAILING COLD FRONT MOVES SEWD OVER TN VALLEY...SRN APPALACHIANS...AND PORTIONS FL PANHANDLE. OPERATIONAL/DETERMINISTIC MODELS AND MANY SREFX MEMBERS NOW INDICATE DEVELOPMENT OF WEAK FRONTAL-WAVE LOW BY EARLY IN PERIOD ACROSS AL...SUBSEQUENTLY MOVING EWD OR NEWD ACROSS GA...POTENTIALLY LINKING WITH DAMMING/PIEDMONT FRONT. PROGS ARE QUITE INCONSISTENT WITH STRENGTH OF THIS FEATURE THROUGHOUT PERIOD...AND WITH TRACK AFTER ABOUT 14/00Z. ...OH VALLEY...LOWER GREAT LAKES REGION... BAND OF TSTMS MAY DEVELOP LATE MORNING INTO AFTERNOON AND MOVE ENEWD ACROSS THIS AREA. MAIN CONCERN ATTM IS AMOUNT/EXTENT OF FAVORABLE INSTABILITY...GIVEN LIKELIHOOD OF AMBIENT CLOUD COVER LIMITING SFC DIABATIC HEATING...AND MIDLEVEL LAPSE RATES JUST SLGTLY GREATER THAN MOIST ADIABATIC. NNE-SSW ORIENTED CORRIDOR OF LARGE SCALE ASCENT -- NEARLY PARALLEL TO FRONT AND JUST AHEAD OF MID-UPPER TROUGH -- SHOULD ENHANCE LAPSE RATES JUST ENOUGH TO SUPPORT SOME SFC-BASED BUOYANCY...PROBABLY AOB 500 J/KG MOST AREAS. DEEP-LAYER WIND PROFILES WILL BE LARGELY UNIDIRECTIONAL WITH WEAK COMPONENT OF MEAN FLOW ACROSS POTENTIAL FORCING BOUNDARY. THEREFORE SVR POTENTIAL APPEARS TOO CONDITIONAL/MRGL FOR CATEGORICAL OUTLOOK ATTM. ...SERN CONUS... SCATTERED TSTMS ARE LIKELY THROUGH MUCH OF PERIOD ACROSS THIS REGION...AMIDST REGIME OF LOW LEVEL WAA AND INCREASINGLY RICH MOISTURE. SOME OF THESE MAY BECOME SUPERCELLS WITH POTENTIAL FOR MRGL HAIL...DAMAGING GUST OR BRIEF TORNADO. WITH CINH EXPECTED TO BE WEAK...AFTERNOON/EARLY EVENING CONVECTION MAY BECOME SFC BASED...WITH STRONG INSOLATION IN ANY RELATIVELY CLOUD-FREE AREAS HELPING TO OFFSET WEAK MIDLEVEL LAPSE RATES FOR MLCAPE POTENTIALLY NEAR 1000 J/KG. MEANWHILE...INCREASING MIDLEVEL GRADIENT WINDS AHEAD OF MID-UPPER TROUGH WILL ENHANCE 0-6 KM SHEAR...PARTICULARLY OVER INLAND AREAS AL/GA/SC. MEANWHILE POTENTIAL EXISTS FOR BACKED SFC FLOW INVOF SFC LOW...CONTRIBUTING TO MESOSCALE AREA OF ENLARGED 0-3 KM AGL HODOGRAPHS. CONSIDERABLE UNCERTAINTY EXISTS ABOUT STRENGTH OF HEATING/DESTABILIZATION...AND AS MENTIONED ABOVE...REGARDING TRACK/STRENGTH OF WAVE LOW. THEREFORE WILL KEEP TOTAL SVR PROBABILITIES MRGL ATTM UNTIL MESOSCALE FOCI BECOME BETTER DEFINED. ...SWRN CONUS... MID-UPPER LEVEL LOW NOW EVIDENT OVER SWRN AZ IS FCST TO MEANDER ERRATICALLY ACROSS SRN AZ/NWRN SONORA REGION THROUGH PERIOD. ASSOCIATED NW-SE ORIENTED SFC TROUGH -- CONTAINING ONE OR MORE WEAK LOWS -- SHOULD HELP TO MAINTAIN FETCH OF MOISTENING FLOW FROM SE...IN LOW-MIDDLE LEVELS. STEEP DEEP-LAYER LAPSE RATES ARE POSSIBLE WHEN DIURNAL HEATING IS COMBINED WITH MIDLEVEL COOLING ASSOCIATED WITH CYCLONE ALOFT. CLOUDS/PRECIP AND CONVECTIVE STABILIZATION -- RESULTING FROM DAY-1 ACTIVITY -- MAY LIMIT OR FOCUS POTENTIAL ON MESOSCALE. STRONGEST STORMS MAY PRODUCE HAIL/GUSTS NEAR SVR LEVELS. ..EDWARDS.. 09/12/2006  From swody2 at goshenarc.org Tue Sep 19 05:34:29 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 19 Sep 2006 01:34:29 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 190535 SWODY2 SPC AC 190534 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1234 AM CDT TUE SEP 19 2006 VALID 201200Z - 211200Z ...NO SVR TSTM AREAS FORECAST... ...CENTRAL PLAINS... IMPRESSIVE HEIGHT FALLS...ON THE ORDER OF 180-200M DURING THE LATTER HALF OF THE PERIOD...WILL DEVELOP ACROSS THE CNTRL PLAINS WEDNESDAY NIGHT AS A STRONG SPEED MAX DIGS INTO NRN NM...THEN EJECTS NEWD INTO CNTRL KS. THIS FEATURE WILL REQUIRE RAPID ADJUSTMENT AT LOW LEVELS...IN THE LEE OF THE ROCKIES...WHERE DEEPENING SFC CYCLOGENESIS IS EXPECTED ACROSS CO INTO NRN KS/SRN NEB BY 21/12Z. FOCUSED ASCENT DUE TO STRONG LOW LEVEL WAA...AND VORTICITY ADVECTION...WILL RESULT IN STEEPENING LAPSE RATES AND MOISTENING PROFILES ABOVE THE BOUNDARY LAYER AFTER 00Z ACROSS MUCH OF NEB...SWD ACROSS KS INTO NWRN OK. DESPITE A LAG IN BOUNDARY LAYER MOISTURE RETURN INTO THIS REGION...FORECAST SOUNDINGS AND STRENGTH OF UPPER SYSTEM SUGGEST STRONG ELEVATED THUNDERSTORMS ARE POSSIBLE AFTER DARK. MEAGER INSTABILITY WILL BE THE LIMITING FACTOR FOR WIDESPREAD SEVERE...ALTHOUGH A FORCED LINE OF THUNDERSTORMS SHOULD DEVELOP AND PRODUCE AT LEAST MARGINALLY SEVERE HAIL...WITH POSSIBLE LARGER STONES IN ISOLATED LOCATIONS. ..DARROW.. 09/19/2006  From swody2 at goshenarc.org Tue Sep 19 17:31:15 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 19 Sep 2006 13:31:15 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 191732 SWODY2 SPC AC 191731 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1231 PM CDT TUE SEP 19 2006 VALID 201200Z - 211200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... STRONGER TROUGH/UPPER LOW INITIALLY FORECAST OVER THE GREAT BASIN WILL MOVE SEWD ACROSS THE ROCKIES TOWARD THE SRN HIGH PLAINS THIS PERIOD. ASSOCIATED SURFACE LOW WILL ALSO MOVE OUT OF THE ROCKIES INTO THE HIGH PLAINS...WHERE A MAINLY NOCTURNAL/ELEVATED CONVECTIVE EVENT IS EXPECTED. ELSEWHERE...THUNDERSTORMS ARE EXPECTED OVER CENTRAL AND SRN FL...WITH A STABLE ATMOSPHERE ACROSS THE REMAINDER OF THE CONUS LIKELY PRECLUDING APPRECIABLE THUNDER THREAT. ...CENTRAL PLAINS... SLY LOW-LEVEL FLOW IS FORECAST ACROSS THE PLAINS AS SURFACE LOW MOVES EWD ACROSS THE ROCKIES TOWARD THE PLAINS. HOWEVER...RELATIVELY DRY BOUNDARY LAYER WILL PERSIST AS RICHER MOISTURE REMAINS OVER THE GULF S OF MAIN BAROCLINIC ZONE. THEREFORE...EXPECT LIMITED DESTABILIZATION AND A CAPPED BOUNDARY LAYER TO PERSIST THROUGH THE DAY ACROSS THE PLAINS...SUPPRESSING MOST IF NO ALL CONVECTIVE DEVELOPMENT. HOWEVER...LOW-LEVEL JET WILL DEVELOP DURING THE EVENING...IN RESPONSE TO APPROACHING UPPER TROUGH. WITH STEEP LAPSE RATES SPREADING EWD ABOVE LOW-LEVEL WARMING/MOISTENING...EXPECT ELEVATED STORMS TO DEVELOP. SUFFICIENTLY STRONG/VEERING WIND FIELD SHOULD COMBINE WITH RELATIVELY STEEP LAPSE RATES ALOFT TO SUPPORT A FEW STRONGER STORMS -- AND ASSOCIATED THREAT FOR ISOLATED HAIL. ..GOSS.. 09/19/2006  From swody2 at goshenarc.org Wed Sep 20 05:44:53 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 20 Sep 2006 01:44:53 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 200545 SWODY2 SPC AC 200545 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1245 AM CDT WED SEP 20 2006 VALID 211200Z - 221200Z ...NO SVR TSTM AREAS FORECAST... ...CENTRAL PLAINS/LOWER MO VALLEY... EARLY MORNING WV IMAGERY SUPPORTS LATEST MODEL GUIDANCE REGARDING UPPER LOW OVER ORE...DIGGING SEWD INTO THE GREAT BASIN. THIS FEATURE WILL MOVE ACROSS THE CNTRL ROCKIES INTO KS BY 12Z THURSDAY MORNING WHERE SUBSEQUENT STRONG HEIGHT FALLS AND EJECTING SPEED MAX WILL ALLOW UPPER LOW TO LIFT NEWD INTO WRN IA LATE IN THE OVERNIGHT PERIOD. DESPITE RELUCTANCE OF BOUNDARY LAYER MOISTURE TO RETURN ACROSS THE WARM SECTOR AHEAD OF CYCLONE...IT APPEARS STRONG ASCENT AND STEEP LAPSE RATES NORTH OF JET AXIS WILL CONTRIBUTE GREATLY TO THE INSTABILITY REQUIRED FOR LOW-TOPPED CONVECTION AHEAD OF COLD FRONT BY 18Z. EARLY MORNING ACTIVITY MAY ACTUALLY BE ELEVATED IN NATURE...DRIVEN IN LARGE PART DUE TO WARM ADVECTION ATOP THE CAPPED BOUNDARY LAYER. HOWEVER...IT APPEARS DAYTIME HEATING BENEATH COMPACT...AND NEARLY VERTICALLY STACKED...LOW WILL ALLOW AIRMASS TO DESTABILIZE ALONG A NARROW AXIS...AND WITHIN A BRIEF TIME FRAME FOR SFC-BASED THUNDERSTORMS ACROSS MUCH OF ERN KS/SERN NEB. STRONG SHEAR WOULD CERTAINLY SUPPORT STORM ROTATION. AT THIS TIME WILL MAINTAIN LOW PROBABILITIES FOR LOW-TOPPED SUPERCELLS GIVEN THE MEAGER MOISTURE/INSTABILITY EXPECTED. HOWEVER...THIS AREA WILL BE MONITORED FOR A POSSIBLE MESOSCALE-TYPE SEVERE RISK CLOSER TO THE EVENT. ..DARROW.. 09/20/2006  From swody2 at goshenarc.org Wed Sep 20 17:37:25 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 20 Sep 2006 13:37:25 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 201738 SWODY2 SPC AC 201737 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1237 PM CDT WED SEP 20 2006 VALID 211200Z - 221200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... VERY STRONG/PROGRESSIVE UPPER LOW IS FORECAST TO MOVE ACROSS THE CENTRAL AND SRN PLAINS THIS PERIOD...ACCOMPANIED BY VERY STRONG LOWER AND MID TROPOSPHERIC FLOW. ACCOMPANYING SURFACE LOW INITIALLY OVER ERN CO/WRN KS SHOULD MOVE SLOWLY EWD ACROSS KS...THOUGH LEE TROUGHING AND EVENTUAL CYCLOGENESIS ARE FORECAST TO PERSIST ACROSS ERN CO AHEAD OF NEXT SHORT-WAVE TROUGH AS IT ROTATES RAPIDLY SEWD INTO CO LATE. MAIN CONVECTIVE THREAT THIS PERIOD WILL EXIST OVER THE CENTRAL CONUS. HOWEVER...SEVERE POTENTIAL ACROSS THIS REGION REMAINS HIGHLY CONDITIONAL UPON DEGREE OF LOW-LEVEL MOISTURE ADVECTION AND ASSOCIATED AIRMASS DESTABILIZATION AHEAD OF SURFACE TROUGH/DRY LINE OVER KS/OK/N TX DURING THE DAY. ...SRN NEB SWD INTO N TX AND EWD INTO WRN MO/WRN AR... ELEVATED CONVECTION SHOULD BE ONGOING AT THE START OF THE PERIOD WITHIN REGION OF STRONG WARM ADVECTION. SURFACE TROUGH/DRYLINE IS FORECAST TO MOVE EWD ACROSS KS/OK/N TX THIS PERIOD...AS VERY STRONG KINEMATICS OVERSPREAD THE REGION AHEAD OF POTENT UPPER SYSTEM. MID-LEVEL JET STREAK NEAR 80 KT IS FORECAST...ABOVE 50 TO 60 KT SLY LOW-LEVEL JET. RESULTING SHEAR WOULD BE VERY SUPPORTIVE OF SUPERCELLS...AND ACCOMPANYING SEVERE/TORNADO THREAT. HOWEVER...POTENTIAL FOR DEEP/SURFACE-BASED CONVECTIVE DEVELOPMENT REMAINS HIGHLY CONDITIONAL ATTM...AS RICH BOUNDARY-LAYER MOISTURE REMAINS S OF BAROCLINIC ZONE ACROSS THE CENTRAL GULF. LATEST NAM/GFS AS WELL AS SREF GUIDANCE ALL INDICATE VERY MEAGER BOUNDARY LAYER MOISTURE RETURN AND ASSOCIATED AIRMASS DESTABILIZATION AHEAD OF SURFACE TROUGH AS IT SHIFTS RAPIDLY ACROSS THE REGION THROUGH THE AFTERNOON. GIVEN THESE QUESTIONS...WILL MAINTAIN A 5% SEVERE PROBABILITY ATTM. HOWEVER...AN UPGRADE IN RISK LEVEL MAY BE NEEDED...AS CERTAINTY REGARDING DEGREE OF LOW-LEVEL MOISTURE RETURN AND ASSOCIATED DESTABILIZATION INCREASES WITH TIME. ..GOSS.. 09/20/2006  From swody2 at goshenarc.org Thu Sep 21 05:36:42 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Thu, 21 Sep 2006 01:36:42 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 210537 SWODY2 SPC AC 210536 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1236 AM CDT THU SEP 21 2006 VALID 221200Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN KS/ERN OK...NEWD INTO CNTRL IL... ...LOWER/MID MS VALLEY...SERN KS/ERN OK... LATE EVENING MODEL GUIDANCE CONTINUE WITH DIVERGENT SOLUTIONS IN REGARDS TO THE EVOLUTION OF MID U.S. UPPER TROUGH. IT APPEARS THE NAM MODEL IS TOO AGGRESSIVE MAINTAINING DOMINANCE OF LEAD UPPER LOW OVER THE MID MO VALLEY AT THE EXPENSE OF STRONG UPSTREAM SPEED MAX DIGGING INTO THE 4-CORNERS REGION. GFS HAS BEEN VERY CONSISTENT MAINTAINING TWO DISTINCT UPPER LOW/SHORTWAVE TROUGHS THROUGH THE PERIOD. LATEST THINKING IS THE LEAD SYSTEM WILL ROTATE NEWD INTO THE GREAT LAKES BY 18Z FRI WITH TRAILING WARM CONVEYOR BELT AND LLJ ACROSS THE MID MS VALLEY REGION EXPECTED TO GRADUALLY WEAKEN...BUT REMAIN THE FOCUS FOR POTENTIAL SCATTERED THUNDERSTORM DEVELOPMENT THROUGH THE PERIOD. OF MUCH MORE CONCERN IS THE SPEED MAX THAT WILL EJECT ACROSS THE SRN ROCKIES INTO KS DURING THE LATTER HALF OF THE PERIOD. THIS UPSTREAM SPEED MAX SHOULD INDUCE LEE CYCLOGENESIS OVER THE TX PANHANDLE WHICH WILL THEN LIFT NEWD ALONG SHARPENING WARM FRONT THAT WILL RETURN ACROSS THE SRN PLAINS IN THE WAKE OF LEAD SHORTWAVE. BOUNDARY LAYER MOISTURE SHOULD BE OF HIGH QUALITY ACROSS THE WARM SECTOR WITH UPPER 60S/LOWER 70S EXPECTED ACROSS THE SERN HALF OF THE SLIGHT RISK AREA. CONVECTIVE MODE/INITIATION WILL BE SOMEWHAT COMPLEX THROUGH THE PERIOD WITH WEAKENING LOW LEVEL WARM ADVECTION EXPECTED TO MAINTAIN THUNDERSTORM POTENTIAL FROM PORTIONS OF AR INTO IL THROUGH MUCH OF THE DAYLIGHT HOURS. SHEAR PROFILES WILL SUPPORT STORM ROTATION AND THERE APPEARS TO BE A THREAT FOR SUPERCELLS...HOWEVER WEAKENING LLJ THROUGH LATE AFTERNOON MAY LIMIT SEVERE POTENTIAL THROUGH PEAK HEATING. LATER IN THE EVENING...LLJ SHOULD BEGIN TO INCREASE ACROSS THE SRN PLAINS IN RESPONSE TO UPSTREAM SPEED MAX AND SFC WARM FRONT SHOULD LIFT NWD ACROSS ERN OK INTO SERN KS/SWRN MO. THIS SHARPENING BAROCLINIC ZONE WILL MOST LIKELY BE THE FOCUS FOR ROBUST SEVERE THUNDERSTORM DEVELOPMENT DURING THE OVERNIGHT HOURS. SHEAR PROFILES WILL BECOME INCREASINGLY FAVORABLE FOR SUPERCELLS...AND WITH SFC DEW POINTS EXPECTED TO RISE INTO THE LOWER 70S IT APPEARS THE TORNADO THREAT MAY ACTUALLY INCREASE AS WELL. WILL MONITOR THIS REGION FOR A POSSIBLE UPGRADE IN LATER OUTLOOKS. ..DARROW.. 09/21/2006  From swody2 at goshenarc.org Thu Sep 21 17:48:39 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Thu, 21 Sep 2006 13:48:39 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 211749 SWODY2 SPC AC 211748 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1248 PM CDT THU SEP 21 2006 VALID 221200Z - 231200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS ERN IA/SRN WI/NWRN INDIANA/IL/MO/NRN AR/NERN OK... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN UPPER GREAT LAKES REGION SSWWD INTO NERN TX... ...SYNOPSIS... UPPER SHORT-WAVE TROUGH FORECAST ACROSS THE MID MO VALLEY REGION AT THE START OF THE PERIOD SHOULD CONTINUE NWD...WHILE SECOND SHORT-WAVE TROUGH MOVES ESEWD ACROSS THE ROCKIES TOWARD THE CENTRAL PLAINS AROUND LARGER MID-LEVEL VORTEX. STRONG MID-LEVEL SPEED MAX ASSOCIATED WITH THIS TROUGH WILL SHIFT EWD ACROSS THE SRN ROCKIES/SRN PLAINS...AND INTO THE MID MO VALLEY REGION BY THE END OF THE PERIOD. AT THE SURFACE...MODELS DIFFER IN LOCATION OF PRIMARY SURFACE LOW DUE TO SMALLER-SCALE COMPLEXITY WITHIN THE LARGE UPPER TROUGH. HOWEVER...GENERAL AGREEMENT EXISTS THAT RICH BOUNDARY LAYER MOISTURE WILL SPREAD NWD ACROSS THE CENTRAL THIRD OF THE CONUS AHEAD OF AN EWD-MOVING COLD FRONT. COMBINATION OF RICH BOUNDARY LAYER MOISTURE SPREADING NWD BENEATH A VERY STRONG/FAVORABLY-VEERING WIND FIELD WITH HEIGHT SUGGESTS THAT A SIGNIFICANT/WIDESPREAD SEVERE WEATHER EVENT WILL UNFOLD THIS PERIOD. ...SRN PORTIONS OF THE UPPER GREAT LAKES SSWWD INTO NERN TX... CONVECTION IS FORECAST TO BE ONGOING AT THE START OF THE PERIOD ACROSS PARTS OF AR/MO/IL/IA AND VICINITY...IN CONJUCTION WITH STRONG/SLY LOW-LEVEL JET AND BROAD/ASSOCIATED ZONE OF WARM ADVECTION. ATTM...IT APPEARS THAT ONGOING STORMS SHOULD BE LARGELY SUB-SEVERE...EXCEPT POSSIBLY ACROSS AR ON LEADING EDGE OF RETURNING MOISTURE. THOUGH THIS ONGOING PRECIPITATION INJECTS A DEGREE OF UNCERTAINTY INTO THE DAY 2 FORECAST...MODELS GENERALLY AGREE THAT MOST OF THE CONVECTION SHOULD SHIFT N AND E WITH TIME...WHILE VERY MOIST BOUNDARY LAYER ADVECTS NWD ACROSS AN EXPANDING WARM SECTOR. ATTM...IT APPEARS THAT AT LEAST SOME DAYTIME HEATING WILL OCCUR ACROSS THE WARM SECTOR...RESULTING IN MODERATE DESTABILIZATION ACROSS THE MDT RISK AREA. THOUGH A STRONG MID-LEVEL FEATURE DOES NOT APPEAR LIKELY TO AFFECT THIS REGION...SMALLER/MORE SUBTLE FEATURES WILL MOVE NEWD IN SWLY FLOW AROUND SERN FRINGES OF LARGE/POSITIVELY-TILTED TROUGH. THIS SHOULD SUPPORT THE DEVELOPMENT ALONG PRIMARY LOW-LEVEL CONVERGENCE AXIS WHICH SHOULD BE MOVING ACROSS ERN KS/ERN OK INTO WRN MO AND NWRN AR DURING THE AFTERNOON. WITH THE LACK OF A PRONOUNCED SMALL-SCALE UPPER FEATURE...IT APPEARS ATTM THAT DISCRETE STORM DEVELOPMENT SHOULD OCCUR WITHIN POCKETS OF GREATER INSTABILITY. WITH VERY STRONG/WEAKLY DIFFLUENT SWLY FLOW ALOFT ABOVE VERY STRONG SSWLY LOW-LEVEL WIND FIELD...DEGREE OF SHEAR WILL ALLOW STORMS TO RAPIDLY ACQUIRE STRONG ROTATION. ALONG WITH THREAT FOR DAMAGING WINDS AND HAIL...MOIST BOUNDARY LAYER/LOW LCLS COMBINED WITH VERY STRONG LOW-LEVEL SHEAR WILL SUPPORT TORNADOES. THOUGH SOME UNCERTAINTY STILL EXISTS -- PARTICULARLY REGARDING EARLIER CONVECTION AND ITS EFFECT ON THE THERMODYNAMIC ENVIRONMENT...IT WOULD APPEAR THAT A SIGNIFICANT TORNADOES WILL BE POSSIBLE -- PARTICULARLY ACROSS MO AND INTO IL DURING THE AFTERNOON AND EVENING. LOW-LEVEL JET IS FORECAST TO FURTHER STRENGTHEN OVERNIGHT...WITH STRONGEST WARM ADVECTION FORECAST TO SHIFT NWD AND EWD INTO THE UPPER GREAT LAKES/OH VALLEY REGION. THOUGH THIS WILL LIKEWISE ALLOW CONVECTION -- AND SOME SEVERE THREAT -- TO EXPAND NWD AND EWD...MAIN THREAT SHOULD PERSIST FROM IL SSWWD...WHERE MOST FAVORABLE COMBINATION OF INSTABILITY AND SHEAR SHOULD REMAIN. ..GOSS.. 09/21/2006  From swody2 at goshenarc.org Thu Sep 21 19:29:39 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Thu, 21 Sep 2006 15:29:39 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 211930 SWODY2 SPC AC 211929 DAY 2 CONVECTIVE OUTLOOK RESENT 1 NWS STORM PREDICTION CENTER NORMAN OK 0229 PM CDT THU SEP 21 2006 VALID 221200Z - 231200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS ERN IA/SRN WI/NWRN INDIANA/IL/MO/NRN AR/NERN OK... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN UPPER GREAT LAKES REGION SSWWD INTO NERN TX... ...SYNOPSIS... UPPER SHORT-WAVE TROUGH FORECAST ACROSS THE MID MO VALLEY REGION AT THE START OF THE PERIOD SHOULD CONTINUE NWD...WHILE SECOND SHORT-WAVE TROUGH MOVES ESEWD ACROSS THE ROCKIES TOWARD THE CENTRAL PLAINS AROUND LARGER MID-LEVEL VORTEX. STRONG MID-LEVEL SPEED MAX ASSOCIATED WITH THIS TROUGH WILL SHIFT EWD ACROSS THE SRN ROCKIES/SRN PLAINS...AND INTO THE MID MO VALLEY REGION BY THE END OF THE PERIOD. AT THE SURFACE...MODELS DIFFER IN LOCATION OF PRIMARY SURFACE LOW DUE TO SMALLER-SCALE COMPLEXITY WITHIN THE LARGE UPPER TROUGH. HOWEVER...GENERAL AGREEMENT EXISTS THAT RICH BOUNDARY LAYER MOISTURE WILL SPREAD NWD ACROSS THE CENTRAL THIRD OF THE CONUS AHEAD OF AN EWD-MOVING COLD FRONT. COMBINATION OF RICH BOUNDARY LAYER MOISTURE SPREADING NWD BENEATH A VERY STRONG/FAVORABLY-VEERING WIND FIELD WITH HEIGHT SUGGESTS THAT A SIGNIFICANT/WIDESPREAD SEVERE WEATHER EVENT WILL UNFOLD THIS PERIOD. ...SRN PORTIONS OF THE UPPER GREAT LAKES SSWWD INTO NERN TX... CONVECTION IS FORECAST TO BE ONGOING AT THE START OF THE PERIOD ACROSS PARTS OF AR/MO/IL/IA AND VICINITY...IN CONJUCTION WITH STRONG/SLY LOW-LEVEL JET AND BROAD/ASSOCIATED ZONE OF WARM ADVECTION. ATTM...IT APPEARS THAT ONGOING STORMS SHOULD BE LARGELY SUB-SEVERE...EXCEPT POSSIBLY ACROSS AR ON LEADING EDGE OF RETURNING MOISTURE. THOUGH THIS ONGOING PRECIPITATION INJECTS A DEGREE OF UNCERTAINTY INTO THE DAY 2 FORECAST...MODELS GENERALLY AGREE THAT MOST OF THE CONVECTION SHOULD SHIFT N AND E WITH TIME...WHILE VERY MOIST BOUNDARY LAYER ADVECTS NWD ACROSS AN EXPANDING WARM SECTOR. ATTM...IT APPEARS THAT AT LEAST SOME DAYTIME HEATING WILL OCCUR ACROSS THE WARM SECTOR...RESULTING IN MODERATE DESTABILIZATION ACROSS THE MDT RISK AREA. THOUGH A STRONG MID-LEVEL FEATURE DOES NOT APPEAR LIKELY TO AFFECT THIS REGION...SMALLER/MORE SUBTLE FEATURES WILL MOVE NEWD IN SWLY FLOW AROUND SERN FRINGES OF LARGE/POSITIVELY-TILTED TROUGH. THIS SHOULD SUPPORT THE DEVELOPMENT ALONG PRIMARY LOW-LEVEL CONVERGENCE AXIS WHICH SHOULD BE MOVING ACROSS ERN KS/ERN OK INTO WRN MO AND NWRN AR DURING THE AFTERNOON. WITH THE LACK OF A PRONOUNCED SMALL-SCALE UPPER FEATURE...IT APPEARS ATTM THAT DISCRETE STORM DEVELOPMENT SHOULD OCCUR WITHIN POCKETS OF GREATER INSTABILITY. WITH VERY STRONG/WEAKLY DIFFLUENT SWLY FLOW ALOFT ABOVE VERY STRONG SSWLY LOW-LEVEL WIND FIELD...DEGREE OF SHEAR WILL ALLOW STORMS TO RAPIDLY ACQUIRE STRONG ROTATION. ALONG WITH THREAT FOR DAMAGING WINDS AND HAIL...MOIST BOUNDARY LAYER/LOW LCLS COMBINED WITH VERY STRONG LOW-LEVEL SHEAR WILL SUPPORT TORNADOES. THOUGH SOME UNCERTAINTY STILL EXISTS -- PARTICULARLY REGARDING EARLIER CONVECTION AND ITS EFFECT ON THE THERMODYNAMIC ENVIRONMENT...IT WOULD APPEAR THAT A SIGNIFICANT TORNADOES WILL BE POSSIBLE -- PARTICULARLY ACROSS MO AND INTO IL DURING THE AFTERNOON AND EVENING. LOW-LEVEL JET IS FORECAST TO FURTHER STRENGTHEN OVERNIGHT...WITH STRONGEST WARM ADVECTION FORECAST TO SHIFT NWD AND EWD INTO THE UPPER GREAT LAKES/OH VALLEY REGION. THOUGH THIS WILL LIKEWISE ALLOW CONVECTION -- AND SOME SEVERE THREAT -- TO EXPAND NWD AND EWD...MAIN THREAT SHOULD PERSIST FROM IL SSWWD...WHERE MOST FAVORABLE COMBINATION OF INSTABILITY AND SHEAR SHOULD REMAIN. ..GOSS.. 09/21/2006  From swody2 at goshenarc.org Fri Sep 22 05:59:11 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 22 Sep 2006 01:59:11 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 220600 SWODY2 SPC AC 220559 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1259 AM CDT FRI SEP 22 2006 VALID 231200Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-MS VALLEY...OH VALLEY...GREAT LAKES...OZARKS AND SRN PLAINS... ...MID-MS VALLEY/OZARKS/OH VALLEY/GREAT LAKES... AN IMPRESSIVE UPPER-LOW SHOULD BE IN THE NRN PLAINS SATURDAY MORNING WITH THE LOW FORECAST TO EJECT NEWD ACROSS THE UPPER MIDWEST SATURDAY AFTERNOON. SEVERAL STRONG TO POSSIBLY SEVERE MESOSCALE CONVECTIVE SYSTEMS SHOULD BE ONGOING AT THE BEGINNING OF THE PERIOD ALONG AND AHEAD OF A FRONTAL BOUNDARY EXTENDING SSWWD FROM A SFC LOW IN THE UPPER MIDWEST ACROSS IA INTO WRN MO AND ERN OK. SFC DEWPOINTS AHEAD OF THE BOUNDARY SHOULD BE IN THE UPPER 60S TO LOWER 70S F WHICH MAY RESULT IN WIDESPREAD MODERATE INSTABILITY ACROSS THE WARM SECTOR BY SATURDAY AFTERNOON. AS A RESULT...THUNDERSTORM COVERAGE SHOULD INCREASE ALONG AND AHEAD OF THE FRONT WITH SQUALL-LINE FORMATION LIKELY BY LATE AFTERNOON INTO THE EVENING ACROSS THE OH VALLEY...MID-MS VALLEY AND OZARKS. FORECAST SOUNDINGS SATURDAY AFTERNOON AND EVENING ACROSS THE REGION SHOW 0-6 KM SHEAR VALUES IN THE 50 TO 70 KT RANGE SUGGESTING SHEAR PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. THE LARGE NUMBER OF STORMS FORECAST IN THIS FAVORABLE WIND ENVIRONMENT SHOULD RESULT IN A MIXTURE OF STORM MODE WITH SUPERCELLS...BOW ECHOES AND SEVERE MULTICELLS ALL LIKELY. SUPERCELLS WILL BE MOST LIKELY IN AREAS OF ENHANCED INSTABILITY WHERE STORMS REMAIN DISCRETE. SUPERCELLS WILL ALSO BE POSSIBLE OUT AHEAD OF THE SQUALL-LINE OR ON THE SRN END OF CONVECTIVE LINES. SUPERCELLS AND BOW ECHOES WILL ALSO LIKELY BE EMBEDDED IN THE SQUALL-LINE. SEVERAL TORNADOES MAY OCCUR WITH SUPERCELLS AND/OR WITH THE STRONGER BOW ECHOES. THE TORNADO THREAT SHOULD BE THE GREATEST IN THE OH VALLEY ON THE NORTHWEST SIDE OF A 60 KT LOW-LEVEL JET WHERE LOW-LEVEL SHEAR SHOULD BE ENHANCED. THIS AREA IS ALSO FORECAST TO HAVE THE GREATEST LARGE-SCALE ASCENT ASSOCIATED WITH THE EJECTING UPPER-LOW. WIND DAMAGE AND LARGE HAIL WILL ALSO BE LIKELY WITH THE SUPERCELLS AND STRONGER BOWING SEGMENTS. THE LARGE NUMBER OF STORMS AND WIDESPREAD CLOUD COVER MAY INHIBIT DESTABILIZATION OVER SOME AREAS AND THE EXTENT OF DESTABILIZATION STILL REMAINS UNCERTAIN. IF IT APPEARS MODERATE INSTABILITY WILL BECOME WIDESPREAD WITH AN INTENSE SQUALL-LINE AND/OR A LARGE NUMBER OF RELATIVELY DISCRETE STORMS...THEN AN UPGRADE TO MODERATE RISK MAY BECOME NECESSARY IN LATER OUTLOOKS. ....SRN PLAINS... WEST TO SOUTHWEST FLOW ALOFT WILL IN BE IN PLACE ACROSS THE SRN PLAINS AHEAD OF AN APPROACHING UPPER-LEVEL TROUGH. MODEL FORECASTS DISAGREE ON WHETHER CONVECTIVE CLUSTERS WILL BE ONGOING AT THE BEGINNING OF THE PERIOD AHEAD OF A COLD FRONT LOCATED FROM ERN OK INTO CNTRL TX. MODEL FORECASTS DO AGREE WITH DEVELOPING MODERATE INSTABILITY ACROSS A WIDESPREAD AREA AHEAD OF THE FRONT IN CNTRL AND ERN TX. THIS SHOULD RESULT IN THUNDERSTORM INITIATION JUST ALONG AND JUST AHEAD OF THE BOUNDARY WITH THE DEVELOPMENT OF A SQUALL-LINE AND/OR A BROKEN LINE SEGMENT GRADUALLY ORGANIZING DURING THE AFTERNOON AND EARLY EVENING. FORECAST SOUNDINGS LATE SATURDAY AFTERNOON ACROSS THE REGION SHOW 0-6 KM SHEAR VALUES IN THE 35 TO 45 KT RANGE SUGGESTING SHEAR WILL BE ADEQUATE FOR ISOLATED SUPERCELLS AND SEVERE MULTICELLS ALONG AND AHEAD OF THE FRONT. ALTHOUGH LOW-LEVEL FLOW IS FORECAST TO BE STRONGER NORTHEAST OF THE REGION...AN ISOLATED TORNADO THREAT MAY STILL EXIST WITH THE STRONGER SUPERCELLS DURING THE LATE AFTERNOON AND EARLY EVENING. ISOLATED WIND DAMAGE AND LARGE HAIL WILL BE POSSIBLE WITH SUPERCELLS AND BOWING SEGMENTS ALONG THE CONVECTIVE LINE DURING THE AFTERNOON AND EVENING. ..BROYLES.. 09/22/2006  From swody2 at goshenarc.org Fri Sep 22 17:24:59 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 22 Sep 2006 13:24:59 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 221725 SWODY2 SPC AC 221724 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1224 PM CDT FRI SEP 22 2006 VALID 231200Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES REGION SWWD INTO E TX... ...SYNOPSIS... LARGE/POSITIVELY-TILTED UPPER TROUGH IS FORECAST TO INITIALLY EXTEND FROM THE PLAINS INTO THE ROCKIES/GREAT BASIN...WITH A COLD FRONT MOVING EWD/SEWD ACROSS MO/CENTRAL OK/NRN AND WRN TX. FAIRLY SUBSTANTIAL DIFFERENCES EXIST BETWEEN THE NAM AND GFS HOWEVER...IN PROGRESSION OF THE SYNOPTIC-SCALE ENVIRONMENT THROUGH THE PERIOD. THE GFS IS FASTER THAN THE NAM WITH REGARDS TO THE EWD MOVEMENT OF THE UPPER TROUGH -- AND THEREFORE WITH THE ASSOCIATED COLD FRONTAL PROGRESSION. IN GENERAL HOWEVER...EXPECT THE UPPER TROUGH AND ASSOCIATED SURFACE FRONT TO PROGRESS EWD WITH TIME...WHILE MOIST WARM SECTOR AND STRONG FLOW ALOFT CONTINUE TO SUPPORT A FAIRLY SIGNIFICANT SEVERE THREAT -- LIKELY CENTERED ON THE MID MS/OH VALLEY REGION. ...GREAT LAKES/OH VALLEY REGION SWWD INTO E TX... STRONG/SEVERE STORMS SHOULD BE ONGOING AT THE START OF THE PERIOD...BOTH ALONG AND AHEAD OF COLD FRONT AS WELL AS ACROSS THE OH VALLEY/MIDWEST REGION IN WARM ADVECTION REGIME. THOUGH DEGREE OF DAYTIME DESTABILIZATION IS DIFFICULT TO DETERMINE ATTM DUE TO WIDESPREAD CLOUDS/PRECIPITATION...MOIST WARM SECTOR WILL LIKELY SUPPORT A SUFFICIENT THERMODYNAMIC ENVIRONMENT FOR A DIURNAL INCREASE IN STORM COVERAGE AND INTENSITY. GREATEST INSTABILITY IS EXPECTED TO DEVELOP FROM THE MID MS/LOWER OH VALLEY SSWWD...WHILE STRONGER KINEMATIC ENVIRONMENT SHOULD REMAIN FROM OK ENEWD INTO THE MIDWEST/OH VALLEY REGION. THEREFORE -- DESPITE DIFFERENCES IN TIMING AMONGST THE MODELS...MOST FAVORABLE COMBINATION OF SHEAR AND INSTABILITY SHOULD EXTEND FROM SERN OK ENEWD ACROSS THE OH VALLEY REGION. THEREFORE...WILL MAINTAIN HIGHEST PROBABILITY SEVERE THREAT ACROSS THIS REGION. GIVEN MOIST BOUNDARY LAYER AND STRENGTH OF SHEAR...TORNADO POTENTIAL WILL LIKELY EXIST ONCE AGAIN. HOWEVER...WITH SOMEWHAT MORE UNIDIRECTIONAL SWLY FLOW ALOFT...AND STRONGER LINEAR FORCING THIS PERIOD...DAMAGING WINDS WITH A MORE LINEAR CONVECTIVE MODE MAY PREVAIL ON DAY 2. ATTM...WILL NOT INTRODUCE MODERATE RISK -- PRIMARILY DUE TO MODEL DIFFERENCES WHICH MAKE HIGHLIGHTING THE MOST CONCENTRATED AREA OF SEVERE THREAT DIFFICULT ATTM. HOWEVER...LARGE-SCALE ENVIRONMENTAL FACTORS SUGGEST THAT AN UPGRADE TO MODERATE RISK MAY BE NECESSARY IN LATER OUTLOOKS. ..GOSS.. 09/22/2006  From swody2 at goshenarc.org Wed Sep 27 05:38:47 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 27 Sep 2006 01:38:47 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 270539 SWODY2 SPC AC 270538 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1238 AM CDT WED SEP 27 2006 VALID 281200Z - 291200Z ...NO SVR TSTM AREAS FORECAST... ...APPALACHIAN MTNS... A VIGOROUS UPPER-LEVEL TROUGH OVER THE UPPER MIDWEST TONIGHT WILL DIG QUICKLY SEWD INTO THE MS AND OH VALLEYS BY THE DAY 2 PERIOD. THE TROUGH IS FORECAST TO BECOME HIGHLY MERIDIONAL WITH A BAND OF VERY STRONG LARGE-SCALE ASCENT SPREADING SEWD ACROSS THE REGION AHEAD OF THE APPROACHING TROUGH. THIS COMBINED WITH STRONG LOW-LEVEL CONVERGENCE ALONG THE BOUNDARY SHOULD BE FAVORABLE FOR THUNDERSTORM DEVELOPMENT THURSDAY AFTERNOON. ALTHOUGH INSTABILITY SHOULD REMAIN MODEST THURSDAY...FORECAST SOUNDINGS SHOW STRONG WIND FIELDS ASSOCIATED WITH A 90 KT MID-LEVEL JET MAX ROUNDING THE BASE OF THE TROUGH. THIS SHOULD BE SUFFICIENT FOR AT LEAST A MARGINAL SEVERE THREAT IN THE CNTRL AND SRN APPALACHIAN MTNS THURSDAY AFTERNOON. THE GFS AND ECMWF AGREE WITH DEVELOPING A LINE OF CONVECTION IN THE APPALACHIANS WITH THE LINE MOVING ESEWD INTO THE APPALACHIAN FOOTHILLS ACROSS VA...NC AND SC THURSDAY EVENING. THE STRONG SHEAR AND FAST MOVEMENT OF THE UPPER-SYSTEM SHOULD BE FAVORABLE FOR STRONG WIND GUSTS WITH THE BETTER ORGANIZED LINE SEGMENTS. A PLUME OF STEEP MID-LEVEL LAPSE RATES SHOULD BE PRESENT AHEAD OF THE TROUGH MAKING HAIL ALSO POSSIBLE WITH THE STRONGER MULTICELL THUNDERSTORMS. ..BROYLES.. 09/27/2006  From swody2 at goshenarc.org Wed Sep 27 17:22:21 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 27 Sep 2006 13:22:21 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 271722 SWODY2 SPC AC 271721 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 PM CDT WED SEP 27 2006 VALID 281200Z - 291200Z ...NO SVR TSTM AREAS FORECAST... ...EASTERN APPALACHIANS... STRONG SPEED MAX WILL DIG SEWD ACROSS THE LOWER MO VALLEY INTO THE SRN APPALACHIANS BY EARLY EVENING WHERE 12HR HEIGHT FALLS SHOULD BE ON THE ORDER OF 120M. IT APPEARS THE ASSOCIATED FRONTAL ZONE WILL BE STRONGLY FORCED...AND CONVECTIVELY ACTIVE...AS IT PROGRESSES EWD ACROSS THE APPALACHIANS. A NARROW BAND OF THUNDERSTORMS SHOULD EVOLVE DURING THE LATE DAY1 PERIOD FROM THE OH VALLEY...SWWD INTO WRN TN. THIS ACTIVITY SHOULD ADVANCE INTO THE HIGHER ELEVATIONS OF WRN PA...SWWD INTO NRN GA EARLY IN THE PERIOD. AFTERNOON HEATING AHEAD OF WIND SHIFT SHOULD ENHANCE BOUNDARY LAYER INSTABILITY OVER AND TO THE LEE OF THE APPALACHIANS...ALTHOUGH FORECAST SOUNDINGS INDICATE SBCAPE VALUES SHOULD REMAIN GENERALLY IN THE 500-1000 J/KG RANGE. STRONG VERTICAL SHEAR CERTAINLY WOULD SUPPORT ORGANIZED UPDRAFTS...HOWEVER MARGINAL INSTABILITY AND LINEAR STORM MODE WITHIN WEAK MID LEVEL LAPSE RATE ENVIRONMENT SUGGEST MARGINALLY SEVERE WIND GUSTS WILL BE THE MAIN CONCERN WHERE BOUNDARY LAYER HEATING/BUOYANCY CAN DEVELOP AHEAD OF FRONTAL ZONE. ..DARROW.. 09/27/2006  From swody2 at goshenarc.org Fri Sep 1 05:52:58 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 01 Sep 2006 01:52:58 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 010553 SWODY2 SPC AC 010552 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1252 AM CDT FRI SEP 01 2006 VALID 021200Z - 031200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER PATTERN TO REMAIN GENERALLY UNCHANGED ON THE LARGE SCALE THIS PERIOD...WITH STRONGER/MORE ACTIVE FLOW CONFINED TO AREAS WELL N OF THE U.S./CANADA BORDER. MAIN FEATURE OF INTEREST OVER THE CONUS WILL BE A TROUGH OVER THE CENTRAL CONUS/MIDWEST -- COMPRISED OF TWO SMALLER-SCALE CENTERS OF VORTICITY. THE FIRST -- A WEAK UPPER LOW -- IS FORECAST TO MOVE SLOWLY SSEWD ACROSS THE NRN AND CENTRAL HIGH PLAINS...WHILE THE SECOND MOVES NWD ACROSS THE OH VALLEY AND INTO THE GREAT LAKES REGION. AT THE SURFACE...A FRONT IS FORECAST TO MOVE SLOWLY SWD ACROSS TX/THE GULF COAST REGION...AHEAD OF LARGE HIGH PRESSURE OVER THE PLAINS. THOUGH A MOIST AIRMASS IS FORECAST ALONG AND S OF THIS BOUNDARY...WEAK LAPSE RATES WILL LIMIT POTENTIAL FOR DESTABILIZATION...WHILE WEAK WIND FIELD FURTHER LIMITS ANY THREAT FOR STRONG/SEVERE CONVECTION. NAM HINTS AT SOME POTENTIAL FOR A FEW STRONGER STORMS ACROSS THE CAROLINAS DURING THE AFTERNOON INVOF NERN EXTENSION OF AFOREMENTIONED COLD FRONT. HOWEVER...SHEAR AND INSTABILITY SHOULD REMAIN MARGINAL FOR SUPPORTING-+ WELL-ORGANIZED CONVECTION. FURTHER...QUESTIONS REGARDING THE ACTUAL SURFACE PATTERN ACROSS THE ERN U.S. IN THE WAKE OF ERNESTO RENDER THE CONVECTIVE FORECAST DIFFICULT ACROSS THIS REGION -- AND THUS WILL NOT INTRODUCE ANY SEVERE PROBABILITIES ATTM. ..GOSS.. 09/01/2006  From swody2 at goshenarc.org Fri Sep 1 17:22:30 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 01 Sep 2006 13:22:30 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 011723 SWODY2 SPC AC 011722 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1222 PM CDT FRI SEP 01 2006 VALID 021200Z - 031200Z ...NO SVR TSTM AREAS FORECAST... ...ARIZONA... SFC DEWPOINTS SHOULD REMAIN IN THE UPPER 50S TO NEAR 60 F ACROSS MUCH OF THE ARIZONA DESERTS SATURDAY. THIS SHOULD ALLOW FOR SOME DESTABILIZATION ACROSS THE REGION BY SATURDAY AFTERNOON. THUNDERSTORMS WILL LIKELY DEVELOP ON THE MOGOLLON RIM AND CONVECTIVE COVERAGE SHOULD INCREASE BY EARLY EVENING. FORECAST SOUNDINGS EARLY SATURDAY EVENING ACROSS THE REGION SHOW VERY STEEP LAPSE RATES AND STRONG ENOUGH VERTICAL SHEAR FOR ISOLATED STRONG WIND GUSTS WITH THE MORE ORGANIZED MULTICELL THUNDERSTORMS. ...MID-ATLANTIC... THE REMNANTS OF ERNESTO ARE FORECAST TO MOVE NWD ACROSS THE MID-ATLANTIC REGION TONIGHT INTO SATURDAY. ALTHOUGH THE SYSTEM IS LIKELY TO CONTINUE WEAKENING WITH TIME...SOME HEAVY RAINBANDS MAY STILL EXIST WITH ISOLATED THUNDERSTORM ACTIVITY POSSIBLE ON SATURDAY ACROSS THE MID-ATLANTIC. FORECAST SOUNDINGS SATURDAY AFTERNOON ACROSS THE REGION SHOW STRONG ENOUGH VERTICAL SHEAR PROFILES FOR ORGANIZED STORMS. HOWEVER...INSTABILITY WILL LIKELY BE TOO WEAK FOR A THREAT OF ROTATING STORMS. ...UPPER MS VALLEY/MID-MO VALLEY... AN UPPER-LEVEL TROUGH OVER THE NRN HIGH PLAINS IS FORECAST TO CLOSE-OFF AND MOVE SEWD INTO THE NRN PLAINS SATURDAY. MODEL FORECASTS ARE CONSISTENT DEVELOPING THUNDERSTORM ACTIVITY ALONG THE LEADING EDGE OF LARGE-SCALE ASCENT ON THE EAST SIDE OF THE SYSTEM. HOWEVER...INSTABILITY IS FORECAST TO BE WEAK SATURDAY AFTERNOON AND A SEVERE THREAT IS NOT ANTICIPATED ACROSS THE REGION. ..BROYLES.. 09/01/2006  From swody2 at goshenarc.org Sat Sep 2 05:51:11 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 02 Sep 2006 01:51:11 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 020552 SWODY2 SPC AC 020551 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 AM CDT SAT SEP 02 2006 VALID 031200Z - 041200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LARGE-SCALE UPPER PATTERN TO CHANGE LITTLE THIS PERIOD...WITH A TROUGH OFF THE PAC NW COAST...A RIDGE OVER THE ROCKIES...A TROUGH IN THE CENTRAL CONUS...AND A RIDGE OVER THE EAST. THE CENTRAL U.S. TROUGH WILL MAKE SOME EWD PROGRESS WITH TIME...WITH EMBEDDED UPPER LOW MOVING SLOWLY EWD ACROSS THE MID MO VALLEY REGION THROUGH THE PERIOD. AT THE SURFACE...MAIN BAROCLINIC ZONE WILL REMAIN FROM THE ATLANTIC COAST STATES SWWD INTO THE SOUTHEAST...AND THEN WSWWD ACROSS THE GULF COAST REGION INTO S TX. WIDESPREAD LOW-LEVEL NLYS WILL PREVAIL ACROSS MUCH OF THE CONUS FROM THE ROCKIES EWD TO THE APPALACHIANS... WITH A CORRESPONDING LACK OF RICH MOISTURE/SIGNIFICANT INSTABILITY. ...MN SWD INTO NRN MO... DESPITE THE LACK OF A HIGH THETA-E BOUNDARY LAYER AIRMASS...MID-LEVEL COLD POOL /-14 TO -18 C/ ASSOCIATED WITH UPPER LOW WILL MOVE SLOWLY EWD INTO THIS REGION. AS A RESULT...MARGINAL INSTABILITY /AOB 500 J/KG MEAN-LAYER CAPE/ IS EXPECTED NEAR AFTERNOON PEAK HEATING. THIS SHOULD SUPPORT INITIATION OF SCATTERED/LOW-TOPPED STORMS DURING THE AFTERNOON...WHICH SHOULD THEN RAPIDLY DIMINISH AFTER SUNSET. THOUGH INSTABILITY WILL REMAIN LIMITED...40 TO 50 KT CYCLONIC MID-LEVEL JET STREAK ACCOMPANYING THE UPPER LOW SHOULD SPREAD ACROSS NRN MO/ERN IA. RESULTING SHEAR COMBINED WITH DEGREE OF INSTABILITY MAY SUPPORT A FEW ORGANIZED/ROTATING STORMS -- WITH ASSOCIATED THREAT FOR HAIL. WILL INTRODUCE 5% SEVERE PROBABILITY THIS FORECAST TO REFLECT THE POSSIBLE THREAT. ..GOSS.. 09/02/2006  From swody2 at goshenarc.org Sat Sep 2 17:17:09 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 02 Sep 2006 13:17:09 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 021717 SWODY2 SPC AC 021716 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1216 PM CDT SAT SEP 02 2006 VALID 031200Z - 041200Z ...NO SVR TSTM AREAS FORECAST... ...SRN MN/SW WI TO NRN MO... MODELS REMAIN CONSISTENT WITH TRACK OF SD CLOSED UPPER LOW TOWARD THE SE...REACHING CENTRAL IA BY 12Z MONDAY. LARGE SCALE ASCENT OF THIS FEATURE WITHIN EXIT REGION OF ACCOMPANYING 50-60 KT WNWLY MID LEVEL JET IS EXPECTED TO AID IN THUNDERSTORM DEVELOPMENT FROM SRN MN INTO NRN MO. ALTHOUGH DEEP LAYER SHEAR SHOULD BE SUFFICIENT FOR ORGANIZED STORMS...WEAK INSTABILITY IS EXPECTED TO LIMIT SEVERE COVERAGE. A FEW LOW-TOPPED STORMS WILL BE CAPABLE OF PRODUCING HAIL GIVEN COLD POCKET /-14 TO -18 C AT 500 MB/. ...LOWER CO RIVER VALLEY... HURRICANE JOHN IS EXPECTED TO WEAKEN TO A TROPICAL STORM TODAY...PER LATEST NHC GUIDANCE...AS THIS SYSTEM TRACKS NWWD ALONG THE BAJA PENINSULA INTO DAY 2 PERIOD. A NWD SURGE OF MOISTURE /SURFACE DEWPOINTS IN THE 60S/ IS EXPECTED TO SPREAD INTO THE LOWER CO RIVER VALLEY AND SRN CA ON SUNDAY CONTRIBUTING TO MODERATE INSTABILITY AS SURFACE TEMPERATURES RISE THROUGH THE 90S SUNDAY AFTERNOON. MID LEVEL WINDS ACROSS AZ TO SRN CA ARE EXPECTED TO BECOME NELY AS JOHN TRACKS NWWD ALONG CENTRAL BAJA PENINSULA. THIS WILL ALLOW STORMS TO DEVELOP SWWD OFF THE HIGHER TERRAIN INTO THE LOWER CO RIVER VALLEY WHERE MODERATE INSTABILITY AND STEEP LOW LEVEL LAPSE RATES SHOULD FAVOR A POTENTIAL FOR STRONG WIND GUSTS. WEAK DEEP LAYER SHEAR WILL LIKELY LIMIT SEVERE COVERAGE. THUS...HAVE ONLY INTRODUCED A 5% SEVERE PROBABILITY. ..PETERS.. 09/02/2006  From swody2 at goshenarc.org Sun Sep 3 06:07:58 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 03 Sep 2006 02:07:58 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 030604 SWODY2 SPC AC 030603 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0103 AM CDT SUN SEP 03 2006 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... AMPLIFICATION OF THE UPPER PATTERN OVER THE CONUS IS FORECAST THIS PERIOD...AS ERN U.S. TROUGH -- AND EMBEDDED UPPER LOW -- DEEPENS AND MOVES SLOWLY EWD ACROSS THE MS VALLEY REGION...ALLOWING AN EXPANSION OF THE WRN U.S. RIDGE. THE MAIN SURFACE BAROCLINIC ZONE WILL REMAIN IN PLACE FROM THE SERN U.S. WSWWD ACROSS THE GULF COAST REGION AND INTO S TX...WITH NLY LOW-LEVEL FLOW PREVAILING FROM THE PLAINS TO THE APPALACHIANS. A FEW STRONG/POSSIBLY SEVERE STORMS MAY FORM AHEAD OF THE UPPER LOW OVER THE UPPER MS VALLEY REGION...AND IN ELY POST-FRONTAL UPSLOPE FLOW REGIME OVER THE HIGH PLAINS OF CO/NERN NM. HOWEVER...WITH HIGHER THETA-E AIRMASS REMAINING ACROSS S TX AND THE GULF COAST REGION...INSTABILITY -- AND THUS CONVECTIVE INTENSITY -- SHOULD REMAIN LIMITED IN MOST AREAS. ...HIGH PLAINS OF CO/NERN NM... SELY POST-FRONTAL UPSLOPE FLOW IS FORECAST ACROSS THE SRN AND INTO THE CENTRAL HIGH PLAINS...WHERE RELATIVELY MEAGER BOUNDARY-LAYER MOISTURE SHOULD RESULT IN VERY MARGINAL INSTABILITY. SOME DIURNAL CONVECTION IS EXPECTED ACROSS THIS REGION...THOUGH OVERALL STORM INTENSITY SHOULD REMAIN LIMITED DUE TO THERMODYNAMIC DEFICIENCY. IF SUFFICIENT DESTABILIZATION COULD OCCUR...40 KT NWLY MID-LEVEL FLOW ABOVE LOW-LEVEL SELYS WOULD RESULT IN SHEAR SUPPORTIVE OF ORGANIZED STORMS. THEREFORE...WILL INITIATE 5% CONDITIONAL SEVERE PROBABILITY ACROSS THIS REGION. ANY THREAT WOULD RAPIDLY DIMINISH THROUGH THE EVENING. ...ERN IA/NRN IL/SRN WI... DIURNAL STORM DEVELOPMENT IS ANTICIPATED ACROSS ERN IA AND INTO NRN IL/SRN WI...NEAR UPPER LOW AND ASSOCIATED COLD POOL WHERE MARGINAL AFTERNOON DESTABILIZATION IS EXPECTED. WITH COMPACT 35 KT MID-LEVEL JET STREAK FORECAST ON SERN FRINGE OF UPPER LOW...SHEAR SUPPORTIVE OF ORGANIZED/LOW-TOPPED STORMS SHOULD EXIST. THEREFORE...WILL MAINTAIN A 5% SEVERE PROBABILITY ACROSS THIS REGION FOR STRONGER AFTERNOON CONVECTION. ..GOSS.. 09/03/2006  From swody2 at goshenarc.org Sun Sep 3 17:08:11 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 03 Sep 2006 13:08:11 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 031708 SWODY2 SPC AC 031707 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1207 PM CDT SUN SEP 03 2006 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...HIGH PLAINS OF CO/NERN NM... WATER VAPOR IMAGERY CURRENTLY SHOWED A COUPLE OF SHORT WAVE TROUGHS MOVING SSWWD ACROSS WY AND ERN MT. MODELS SUGGEST THE MT IMPULSE WILL TRACK SSEWD ACROSS CO ON MONDAY. STEEP LOW AND MID LEVEL LAPSE RATES COMBINED WITH SURFACE HEATING ARE EXPECTED TO OFFSET MODEST LOW LEVEL MOISTURE AND ALLOW FOR AT LEAST MARGINAL INSTABILITY /MLCAPE 500-1000 J/KG/ TO DEVELOP MONDAY AFTERNOON. OROGRAPHIC FORCING COMBINED WITH ASCENT AHEAD OF MT SHORT WAVE TROUGH SHOULD SUPPORT THUNDERSTORM DEVELOPMENT MAINLY ACROSS THE HIGHER TERRAIN OF SRN CO AND NRN-NERN NM...WITH ACTIVITY MOVING SSEWD INTO THE ADJACENT HIGH PLAINS. THE POTENTIAL WILL EXIST FOR STORMS TO BECOME ORGANIZED AS NWLY MID LEVEL WINDS STRENGTHEN TO AROUND 40 KT BY LATE MONDAY AFTERNOON ATOP ESELY LOW LEVEL WINDS...RESULTING IN 30-40 KT OF DEEP LAYER SHEAR. HOWEVER...OVERALL COVERAGE OF THE SEVERE THREAT SHOULD REMAIN BELOW A CATEGORICAL RISK...GIVEN MARGINAL INSTABILITY. THUS...THIS OUTLOOK WILL MAINTAIN A 5% SEVERE PROBABILITY. ...PART OF UPPER MS VALLEY AND MIDWEST... CLOSED UPPER LOW...CURRENTLY LOCATED OVER THE MID MO RIVER VALLEY PER WATER VAPOR IMAGERY...WILL CONTINUE TO TRACK SLOWLY SEWD FROM IA INTO IL DURING DAY 2 PERIOD. MARGINAL INSTABILITY ACROSS THIS REGION IS EXPECTED TO SUPPORT ANOTHER DAY OF DIURNAL THUNDERSTORM DEVELOPMENT NEAR UPPER LOW AND ASSOCIATED MID LEVEL COLD POCKET /-14 TO -18 C AT 500 MB/. STRONGER MID LEVEL FLOW ALONG THE SRN AND NRN PERIPHERIES OF THE UPPER LOW /MO INTO IL AND NRN WI INTO MN/ INDICATES A POTENTIAL FOR STORM ORGANIZATION ACROSS THESE AREAS... BUT LIMITED INSTABILITY SHOULD PRECLUDE A GREATER COVERAGE OF SEVERE STORMS. ..PETERS.. 09/03/2006  From swody2 at goshenarc.org Mon Sep 4 06:06:53 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Mon, 04 Sep 2006 02:06:53 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 040605 SWODY2 SPC AC 040604 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0104 AM CDT MON SEP 04 2006 VALID 051200Z - 061200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LARGE UPPER RIDGE WILL REMAIN OVER THE WRN CONUS THIS PERIOD...WHILE ERN U.S. TROUGH DIGS SEWD INTO THE OH AND TN VALLEYS/SOUTHEAST STATES. THE DIGGING TROUGH SHOULD DRIVE WEAK CYCLOGENESIS ACROSS GA/THE CAROLINAS ALONG REMNANT BAROCLINIC ZONE. ...THE SOUTHEAST INTO THE CAROLINAS... MOIST BOUNDARY LAYER IS FORECAST AHEAD OF BAROCLINIC ZONE OVER THIS REGION...THOUGH WEAK LAPSE RATES SHOULD LIMIT POTENTIAL FOR DESTABILIZATION. NONETHELESS...LOW-LEVEL UVV ASSOCIATED WITH WEAK CYCLOGENESIS SHOULD RESULT IN STORM DEVELOPMENT FROM GA NEWD INTO THE CAROLINAS BY AFTERNOON...AS UPPER TROUGH APPROACHES. THOUGH OVERALL SEVERE THREAT SHOULD REMAIN LIMITED DUE TO WEAK INSTABILITY...35 KT SWLY MID-LEVEL FLOW MAY AID IN THE DEVELOPMENT OF A FEW STRONGER/SUSTAINED STORMS...AND THEREFORE WILL EXPAND THE 5% SEVERE PROBABILITY E OF THE APPALACHIANS INTO THE CAROLINAS THIS FORECAST. ...MIDDLE OH/TN VALLEYS... MARGINAL DIURNAL DESTABILIZATION IS FORECAST ACROSS THE MIDDLE OH VALLEY REGION AS COLD POOL ASSOCIATED WITH UPPER LOW SPREADS SLOWLY EWD. SCATTERED THUNDERSTORMS WILL LIKELY DEVELOP AHEAD OF UPPER LOW DURING THE AFTERNOON...THOUGH LIMITED DESTABILIZATION SUGGESTS THAT MOST STORMS SHOULD REMAIN WEAK. A FEW STRONGER/WEAKLY-ORGANIZED STORMS -- AIDED BY 35 KT SWLY FLOW AT MID-LEVELS -- MAY DEVELOP ACROSS CENTRAL KY/SRN INDIANA/SWRN OH...ALONG WITH ATTENDANT LOW PROBABILITY SEVERE THREAT. THREAT WILL DIMINISH QUICKLY DURING THE EVENING WITH THE ONSET OF BOUNDARY-LAYER STABILIZATION. ...NERN NM/SERN CO... WEAK DESTABILIZATION ACROSS THE HIGHER TERRAIN OF SERN CO AND ADJACENT NERN NM BENEATH 30 KT NLY FLOW ALOFT MAY RESULT IN A LOW-END SEVERE THREAT AS A FEW WEAKLY-ORGANIZED STORMS DEVELOP DURING THE AFTERNOON. OVERALL THREAT SHOULD REMAIN LOW DUE TO LIMITED INSTABILITY. ..GOSS.. 09/04/2006  From swody2 at goshenarc.org Mon Sep 4 17:31:30 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Mon, 04 Sep 2006 13:31:30 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 041731 SWODY2 SPC AC 041730 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT MON SEP 04 2006 VALID 051200Z - 061200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER LOW CURRENTLY OVER THE UPPER MS VALLEY IS FORECAST TO AMPLIFY SEWD INTO THE OH AND TN VALLEY REGION TUESDAY. AS THIS OCCURS A WEAK SURFACE LOW IS FORECAST TO DEVELOP AND LIFT NEWD ALONG PRE-EXISTING FRONT FROM GA INTO THE CAROLINAS. FARTHER WEST...HIGH PRESSURE WILL CONTINUE TO SETTLE SWD INTO THE PLAINS IN WAKE OF THIS FEATURE. ...GA THROUGH THE CAROLINAS... A MOIST BOUNDARY LAYER WITH DEWPOINTS IN THE LOWER 70S WILL PERSIST IN THE PRE-FRONTAL WARM SECTOR FROM CNTRL/SRN GA NEWD INTO THE ERN CAROLINAS AND SERN VA. POCKETS OF SURFACE HEATING MAY DEVELOP IN WARM SECTOR DURING THE DAY...BUT CAPE IS EXPECTED TO REMAIN GENERALLY AOB 1000 J/KG OWING TO WEAK LAPSE RATES. SOME INCREASE IN MIDDLE TO HIGH LEVEL FLOW MAY OCCUR FROM PARTS OF GA INTO THE CAROLINAS AS THE UPPER TROUGH AMPLIFIES INTO THE OH AND TN VALLEY. HOWEVER...SURFACE DEVELOPMENT AND LOW LEVEL WIND FIELDS ARE EXPECTED TO REMAIN WEAK. STORMS MAY INTENSIFY ALONG AND AHEAD OF THE FRONT AS THE BOUNDARY LAYER DESTABILIZES WITH PRIMARY THREAT BEING ISOLATED STRONG WIND GUSTS. MARGINAL THERMODYNAMIC PROFILES AND MODEST WIND FIELDS THROUGH 6 KM SUGGEST OVERALL THREAT SHOULD REMAIN LIMITED. ...OH VALLEY... SCATTERED STORMS MAY ONCE AGAIN DEVELOP WITHIN ZONE OF ASCENT NEAR VORT MAX CENTER OVER PARTS OF THE OH VALLEY. TEMPERATURES NEAR THE UPPER LOW CENTER ARE NOT FORECAST TO BE AS COOL AS IN PREVIOUS DAYS WITH -15 TO -16 EXPECTED. WHERE BOUNDARY LAYER WARMING CAN OCCUR... MLCAPE AROUND 500 J/KG WILL BE POSSIBLE. A MARGINAL THREAT OF HAIL WILL EXIST WITH THE STRONGER STORMS THROUGH EARLY EVENING...BUT OVERALL THREAT DOES NOT APPEAR TO WARRANT MORE THAN 5% HAIL PROBABILITIES AT THIS TIME. ...SERN CO THROUGH NERN NM... POTENTIAL WILL EXIST FOR STORMS TO DEVELOP OVER THE HIGHER TERRAIN AS THE ATMOSPHERE DESTABILIZES. RESIDUAL LOW LEVEL MOISTURE WITH DEWPOINTS IN THE UPPER 40S NEAR THE FRONT RANGE AND STEEP MID LEVEL LAPSE RATES WILL CONTRIBUTE TO MLCAPE AROUND 500 J/KG. NLY 30 KT WINDS AT 6 KM ABOVE LIGHT SELY LOW LEVEL FLOW WILL CONTRIBUTE TO 0-6 KM SHEAR AT LEAST MARGINALLY SUFFICIENT FOR MID LEVEL UPDRAFT ROTATION. THIS ALONG WITH STEEP MID LEVEL LAPSE RATES SUGGEST HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS. GENERALLY NLY FLOW IN THE 3-8 KM LAYER SUGGESTS STORMS WILL PROBABLY NOT ADVANCE TOO FAR E OF THE HIGHER TERRAIN. ..DIAL.. 09/04/2006  From swody2 at goshenarc.org Tue Sep 5 06:08:13 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 05 Sep 2006 02:08:13 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 050606 SWODY2 SPC AC 050605 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0105 AM CDT TUE SEP 05 2006 VALID 061200Z - 071200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... MID-LEVEL SHORT-WAVE TROUGH SHOULD MOVE ENEWD FROM THE UPPER OH VALLEY ACROSS NEW ENGLAND...BUT LARGE-SCALE MEAN TROUGH WILL REMAIN ACROSS THE ERN 2/3 OF THE CONUS THROUGH THE PERIOD. AT THE SURFACE...COLD FRONT SHOULD LINGER ALONG THE ATLANTIC COASTAL REGION THROUGH MUCH OF THE PERIOD. ...SERN VA SSWWD INTO FAR SERN GA... WEAK LAPSE RATES BUT VERY MOIST BOUNDARY LAYER SHOULD RESULT IN MARGINAL DESTABILIZATION AHEAD OF COLD FRONT. STORMS WILL LIKELY BE ONGOING ACROSS THIS REGION AT THE START OF THE PERIOD...WITH SOME INCREASE IN INTENSITY POSSIBLE AS LOCAL HEATING HELPS BOOST INSTABILITY IN SOME AREAS. THOUGH WEAK LAPSE RATES SUGGEST LITTLE HAIL THREAT...FLOW INCREASING WITH HEIGHT TO 40 TO 50 KT FROM THE SSW AT MID-LEVELS SHOULD PROVIDE SHEAR SUFFICIENT FOR LOCALLY STRONG WIND GUSTS -- AND PERHAPS EVEN A TORNADO OR TWO GIVEN VERY MOIST BOUNDARY-LAYER AIRMASS. ...CENTRAL AND SRN HIGH PLAINS... MARGINAL BOUNDARY LAYER MOISTURE BUT STEEP MID-LEVEL LAPSE RATES AND DAYTIME HEATING SHOULD RESULT IN MARGINAL DESTABILIZATION OVER THE CENTRAL AND SRN HIGH PLAINS. THOUGH OVERALL LACK OF LOW-LEVEL FORCING SUGGESTS THAT WEAK CAPPING SHOULD INHIBIT STORMS FOR MUCH OF THE DAY...SCATTERED TO ISOLATED STORMS SHOULD DEVELOP NEAR PEAK HEATING ACROSS THIS REGION. LOW-LEVEL SLYS BENEATH 20 KT MID-LEVEL NLYS MAY YIELD SHEAR SUFFICIENT FOR A FEW ORGANIZED STORMS -- AND ASSOCIATED HAIL/WIND THREAT. ANY SEVERE POTENTIAL SHOULD BE CONFINED TO THE PERIOD AROUND PEAK HEATING...WITH RAPID STORM WEAKENING ANTICIPATED AFTER SUNSET. ..GOSS.. 09/05/2006  From swody2 at goshenarc.org Tue Sep 5 17:29:10 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 05 Sep 2006 13:29:10 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 051729 SWODY2 SPC AC 051728 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1228 PM CDT TUE SEP 05 2006 VALID 061200Z - 071200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... UPPER TROUGH NOW OVER THE MIDWEST SHOULD EJECT NEWD INTO THE NERN STATES WEDNESDAY. CYCLOGENESIS IS FORECAST OFF THE MID ATLANTIC COAST LATE TONIGHT INTO EARLY WEDNESDAY IN ADVANCE OF THIS FEATURE. AS THIS LOW LIFTS NWD DURING THE DAY...TRAILING COLD FRONT WILL MOVE OFF THE MID ATLANTIC SEABOARD BY EARLY WEDNESDAY AND OFF THE COASTAL CAROLINAS LATER IN THE DAY. FARTHER WEST...A BROAD FETCH OF NLY FLOW ALOFT WILL PERSIST OVER MUCH OF THE CNTRL U.S. BETWEEN THE UPPER LOW IN THE EAST AND AN UPPER LEVEL RIDGE ALONG THE WEST COAST. ...S CNTRL AND SERN CO THROUGH NERN NM... RESIDUAL LOW LEVEL MOISTURE WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S WILL PERSIST OVER THE CNTRL AND SRN HIGH PLAINS BENEATH STEEP LAPSE RATES. MLCAPE FROM 1000 TO 1500 J/KG WILL BE POSSIBLE AS THE BOUNDARY LAYER WARMS DURING THE AFTERNOON. POTENTIAL WILL EXIST FOR WEAK UPPER LEVEL IMPULSES TO MOVE SWD AND ENHANCE ASCENT....AND A FEW STORMS WILL BE POSSIBLE OVER THE HIGHER TERRAIN AS THE ATMOSPHERE DESTABILIZES. STORMS WILL SUBSEQUENTLY SPREAD SSEWD INTO THE HIGH PLAINS. LIGHT SLY BOUNDARY LAYER FLOW ALONG WRN PERIPHERY OF PLAINS SURFACE RIDGE BENEATH 20 TO 25 KT NLY FLOW ALOFT WILL CONTRIBUTE TO 0-6 KM SHEAR AROUND 30 KT. PRIMARY THREATS WILL BE ISOLATED HAIL AND STRONG WIND GUSTS THROUGH EARLY EVENING. ...CAROLINA COASTS... SCATTERED CONVECTION WILL LIKELY BE ONGOING ALONG AND AHEAD OF THE FRONT OVER THE ERN CAROLINAS WEDNESDAY MORNING. WITH STRONGER LOW LEVEL WIND FIELDS EXPECTED TO REMAIN OFFSHORE AND PRESENCE OF WIDESPREAD PRE-FRONTAL CLOUDS...ANY SEVERE THREAT APPEARS MINIMAL. ..DIAL.. 09/05/2006  From swody2 at goshenarc.org Fri Sep 8 05:33:52 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 08 Sep 2006 01:33:52 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 080535 SWODY2 SPC AC 080534 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1234 AM CDT FRI SEP 08 2006 VALID 091200Z - 101200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... SPLIT FLOW...LARGE-SCALE PATTERN IS FORECAST DURING THE DAY TWO PERIOD...CHARACTERIZED BY OMEGA BLOCK ACROSS CANADA AND A WEAKER SRN BRANCH FROM THE GREAT BASIN EWD TO INCREASINGLY CONFLUENT REGION OVER THE OH VALLEY INTO THE NERN STATES. IN THE LOW-LEVELS...PRIMARY FEATURE WILL BE COLD FRONT WHICH WILL PUSH SEWD THROUGH NEW ENGLAND AND THE OH VALLEY. THIS BOUNDARY WILL EXTEND WWD TO LOW PRESSURE AREA DEVELOPING EWD ACROSS KS. ...NEW ENGLAND INTO THE UPPER OH VALLEY... CURRENT SURFACE OBSERVATIONS AND MODEL FORECASTS SUGGEST THAT BOUNDARY LAYER WILL NOT BE PARTICULARLY MOIST AHEAD OF SURFACE FRONT WITH DEWPOINTS LIKELY IN THE 50S TO PERHAPS LOWER 60S. HOWEVER...DAYTIME HEATING COUPLED WITH HEIGHT FALLS/DYNAMIC COOLING AHEAD OF SHORT WAVE TROUGHING DIGGING SEWD THROUGH QUEBEC SHOULD SUPPORT SOME AIR MASS DESTABILIZATION SATURDAY WITH MLCAPES INCREASING TO 500-1000 J/KG AT SOME LOCATIONS. WEAK CAPPING IN CONJUNCTION WITH FRONTAL CONVERGENCE AND INCREASED LARGE-SCALE FORCING FOR ASCENT AHEAD OF UPPER TROUGH WILL ALL CONTRIBUTE TO AN INCREASE IN TSTM COVERAGE THROUGH THE AFTERNOON FROM NRN/CNTRL NEW ENGLAND SWWD THROUGH NY INTO NRN AND CNTRL PARTS OF OH...IND AND IL. FORECAST SOUNDINGS INDICATE THE STRONGEST MID-LEVEL FLOW AND RESULTANT DEEP LAYER SHEAR /30-35 KTS IN THE LOWEST 6 KM AGL/ ACROSS NEW ENGLAND INTO NY...IN CLOSEST PROXIMITY TO MID/UPPER-LEVEL JET STREAKS OVER ERN QUEBEC INTO THE GULF OF ST. LAWRENCE. GIVEN THE MODEST INSTABILITY AND VERTICAL SHEAR...POTENTIAL WILL EXIST FOR A FEW ORGANIZED STORMS WITH A THREAT OF LOCALLY DAMAGING WINDS AND PERHAPS SOME MARGINALLY SEVERE HAIL. ...CNTRL/SRN PLAINS... FAIRLY WIDESPREAD CONVECTIVE DEVELOPMENT IS ANTICIPATED THROUGH THE PERIOD AHEAD OF SRN BRANCH SHORT WAVE TROUGH WHICH WILL SLOWLY SHIFT EWD THROUGH THE CNTRL PLAINS. MODEL GUIDANCE /IN PARTICULAR THE GFS AND SHORT-RANGE ENSEMBLE MEAN SOLUTIONS/ SUGGEST THAT SOME AIR MASS DESTABILIZATION WILL OCCUR SATURDAY AFTERNOON FROM VICINITY OF SURFACE LOW OVER WRN/CNTRL KS SWD ALONG WEAK DRY LINE OR LEE TROUGH INTO WRN TX/WRN OK. GIVEN THE RELATIVELY WEAK VERTICAL SHEAR FORECAST...AND MODEL VARIABILITY IN THE EVOLUTION OF THIS SHORT WAVE TROUGH AND ASSOCIATED CLOUDS/PRECIPITATION...NO SEVERE PROBABILITIES WILL BE INCLUDED ATTM. ...WRN MT/ERN ID... ISOLATED TSTMS WILL BE POSSIBLE AHEAD OF PACIFIC COLD FRONT SATURDAY AFTERNOON INTO EVENING ALONG SRN FRINGE OF STRONG SHORT WAVE TROUGH LIFTING NEWD THROUGH BRITISH COLUMBIA INTO ALBERTA. BOTH VERTICAL SHEAR AND INSTABILITY ARE FORECAST TO BE MARGINAL...THOUGH THE PRESENCE OF STEEP LOW-LEVEL LAPSE RATES MAY SUPPORT A FEW STRONG DOWNBURSTS WITH THE STRONGEST STORMS. ..MEAD.. 09/08/2006  From swody2 at goshenarc.org Fri Sep 8 17:30:35 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 08 Sep 2006 13:30:35 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 081733 SWODY2 SPC AC 081730 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT FRI SEP 08 2006 VALID 091200Z - 101200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... A SHORTWAVE TROUGH WILL AMPLIFY SEWD INTO THE GREAT LAKES AND NERN STATES SATURDAY. THIS WILL RESULT IN A COLD FRONT CURRENTLY FROM SERN CANADA SWWD INTO THE GREAT LAKES CONTINUING SEWD INTO THE NERN U.S. AND OH VALLEY. SWRN PORTION OF THIS BOUNDARY WILL LIKELY SLOW OR STALL AS A SHORTWAVE TROUGH NOW OVER THE GREAT BASIN ADVANCES EWD INTO THE CNTRL HIGH PLAINS. ...NERN STATES AND OH VALLEY... SURFACE HEATING AHEAD OF COLD FRONT AND LOW LEVEL DEWPOINTS IN THE 50S WILL CONTRIBUTE TO MODERATE INSTABILITY SATURDAY FROM PORTIONS OF THE NERN U.S. INTO THE OH VALLEY. HOWEVER...MLCAPE SHOULD REMAIN GENERALLY BELOW 1200 J/KG OWING TO MODEST LOW LEVEL MOISTURE AND 700-500 MB LAPSE RATES. STORMS WILL LIKELY REDEVELOP ALONG THE FRONT BY LATE MORNING OR EARLY AFTERNOON AND SUBSEQUENTLY SPREAD SEWD. STRONGER WIND PROFILES WILL REMAIN IN THE POST FRONTAL ENVIRONMENT IN ASSOCIATION WITH SEWD ADVANCING SHORTWAVE TROUGH. WIND PROFILES IN VICINITY OF FRONT WILL REMAIN UNIDIRECTIONAL WLY WITH 25 TO 30KT IN THE 850 TO 300 MB LAYER AND MODEST VERTICAL SHEAR. THIS SUGGEST STORM MODE SHOULD REMAIN MULTICELLULAR...BUT WITH SOME STORMS EVOLVING INTO LINE SEGMENTS OR CLUSTERS AS THEY MOVE SEWD. ISOLATED DAMAGING WIND GUSTS AND HAIL WILL BE THE MAIN THREATS. THIS AREA WILL BE MONITORED FOR A POSSIBLE UPGRADE TO SLIGHT RISK IN DAY 1 OUTLOOKS. ...CNTRL PLAINS... CONVECTION WILL INCREASE WITHIN ZONE OF WARM ADVECTION AND LARGE SCALE AHEAD OF EWD ADVANCING SHORTWAVE TROUGH. WEAK CYCLOGENESIS AND A 30 TO 35 KT SLY LOW LEVEL JET ARE FORECAST IN ASSOCIATION WITH THIS FEATURE ACROSS KS. THIS WILL ENHANCE ISENTROPIC ASCENT N OF SWD ADVANCING FRONT FROM NRN KS INTO NEB WHERE PRECIPITATION SHOULD BE MORE WIDESPREAD BUT INSTABILITY MORE LIMITED. BEST CHANCE FOR SOME DESTABILIZATION WILL EXIST S OF FRONT WHERE POCKETS OF SURFACE HEATING MAY DEVELOP. HOWEVER...CAPE WILL BE LIMITED BY MODEST LAPSE RATES AND LOW LEVEL MOISTURE. LOW LEVEL WIND PROFILES ASSOCIATED WITH LOW LEVEL JET AND BACKED FLOW E OF SURFACE LOW WILL CONTRIBUTE TO HODOGRAPHS FAVORABLE FOR UPDRAFT ROTATION OVER PORTIONS OF CNTRL OR N CNTRL KS. HOWEVER...THE BEST LOW LEVEL SHEAR WILL MOST LIKELY REMAIN IN THE CLOUDY...COOLER AIR. THIS ALONG WITH MODEST INSTABILITY AND LAPSE RATES IN WARM SECTOR SUGGEST SEVERE THREAT SHOULD REMAIN LOW. ..DIAL.. 09/08/2006  From swody2 at goshenarc.org Sat Sep 9 05:46:59 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 09 Sep 2006 01:46:59 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 090549 SWODY2 SPC AC 090548 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1248 AM CDT SAT SEP 09 2006 VALID 101200Z - 111200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LATEST MODEL GUIDANCE SHOWS A LARGE DEGREE OF VARIABILITY IN EVOLUTION OF MID/UPPER-LEVEL CIRCULATION EMBEDDED WITHIN A WEAK SUB-TROPICAL BRANCH OF WESTERLIES OVER THE CNTRL/SRN PLAINS. THE GFS TAKES THIS FEATURE E INTO THE LOWER MO VALLEY...WITH THE NAM/WRF THE FARTHEST S AND THE ECMWF INDICATING LITTLE MOVEMENT THROUGH THE PERIOD. SIMILARLY...DIFFERENCES EXIST IN LOCATION AND TRACK OF ATTENDANT SURFACE LOW AND SURFACE FRONT...WITH LOW SEVERE PROBABILITIES ASSIGNED TO ROUGHLY A MEAN COLD FRONTAL POSITION AT THE TIME OF PEAK HEATING. ...CNTRL/SRN PLAINS... GIVEN THESE DIFFERENCES...CONSIDERABLE UNCERTAINTY EXISTS IN THE INITIATION AND EVOLUTION OF DIURNAL TSTM DEVELOPMENT SUNDAY AFTERNOON AND EVENING. IT DOES APPEAR THAT FAIRLY WIDESPREAD CLOUDS AND PRECIPITATION WILL LIMIT AIR MASS DESTABILIZATION AHEAD OF SURFACE LOW AND COLD FRONT OVER KS. FARTHER TO THE S...DEWPOINTS IN MID 50S TO LOWER 60S COUPLED WITH ANTICIPATED STRONGER DIABATIC HEATING SHOULD CONTRIBUTE TO THE DEVELOPMENT OF MODERATE AFTERNOON INSTABILITY AHEAD OF FRONT FROM PORTIONS OF THE TX PNHDL AND S PLAINS EWD INTO WRN AND PERHAPS CNTRL OK WITH MLCAPES OF 1000-1500 J/KG. TSTMS ARE EXPECTED TO BECOME INCREASINGLY LIKELY BY AFTERNOON AS FRONT ENCOUNTERS THIS STRONGER INSTABILITY. THOUGH AMBIENT WIND FIELDS WILL NOT BE PARTICULARLY STRONG...FORECAST SOUNDINGS INDICATE PRONOUNCED VEERING THROUGH THE LOWEST 3 KM AGL WITH 30-35 KTS OF EFFECTIVE BULK SHEAR. THIS COMBINATION OF MODEST INSTABILITY AND SHEAR SHOULD SUPPORT AT LEAST A FEW ORGANIZED STORMS CAPABLE OF LOCALLY STRONG WIND GUSTS AND SEVERE HAIL THROUGH THE AFTERNOON AND EVENING HOURS. ..MEAD.. 09/09/2006  From swody2 at goshenarc.org Sat Sep 9 17:17:44 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sat, 09 Sep 2006 13:17:44 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 091720 SWODY2 SPC AC 091719 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1219 PM CDT SAT SEP 09 2006 VALID 101200Z - 111200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... ALTHOUGH THE LATEST MODEL RUNS ARE SIMILAR IN DEPICTING A BROAD TROUGH OVER THE CENTRAL PORTIONS OF THE COUNTRY ON SUNDAY...THE GFS HAS A MORE PRONOUNCED UPPER TROUGH AXIS AND IS FURTHER EWD WITH THE SYSTEM THAN THE NAM. WILL TREND TOWARD THE GFS SINCE THE NAM HAS BEEN SPEEDING UP THE MOTION OF THE SYSTEM THE PAST FEW RUNS. THUS...EXPECT WEAK SURFACE LOW...ASSOCIATED WITH UPPER TROUGH...TO BE LOCATED IN NWRN MO BY LATE SUNDAY AFTERNOON WITH A TRAILING COLD FRONT EXTENDING SWWD INTO NERN OK AND THEN WSWWD INTO THE SRN TX PANHANDLE. CONVECTION IS EXPECTED NEAR THIS FRONT AND ALSO ACROSS THE ROCKIES...WHERE MOISTURE WILL REMAIN TRAPPED UNDER A WEAK UPPER RIDGE...AND ALONG THE GULF COAST STATES AS WEAK HIGH LEVEL IMPULSES MOVE EWD ACROSS THE REGION. ...WRN MO/ERN KS SWWD INTO THE TX PANHANDLE... ALTHOUGH CONVECTION IS FORECAST TONIGHT FROM WRN KS SWD INTO THE TX PANHANDLE...THIS CONVECTION SHOULD WEAKEN SUNDAY MORNING AS IT SPREADS EWD INTO A MORE STABLE ENVIRONMENT OVER ERN KS AND CENTRAL OK. HOWEVER...LARGE SCALE LIFTING WITH THE UPPER TROUGH AND FRONTAL CONVERGENCE SHOULD BE ENOUGH FOR SCATTERED THUNDERSTORMS TO REDEVELOP ALONG AND AHEAD OF THE FRONT DURING THE AFTERNOON. THOUGH IT WILL NOT BE PARTICULARLY MOIST IN THE BOUNDARY LAYER...LOWER TO MID 60 DEWPOINTS AND TEMPERATURES WARMING INTO THE 80S SHOULD RESULT IN MLCAPES AROUND 1000 J/KG. WIND FIELDS ARE NOT FORECAST TO BE STRONG...THOUGH VEERING WIND PROFILES IN THE LOWER 3 KM SHOULD SUPPORT EFFECTIVE SHEAR RANGING FROM 25-35 KT. THE AMOUNT OF INSTABILITY AND SHEAR SHOULD SUPPORT AT LEAST A FEW ORGANIZED STORMS FROM WRN MO/ERN KS SWWD INTO THE TX PANHANDLE. RELATIVELY STEEP LASE RATES IN THE LOWER 2-3 KM INDICATE THAT LOCALLY STRONG/SEVERE WIND GUSTS WOULD BE THE MAIN THREAT. ..IMY.. 09/09/2006  From swody2 at goshenarc.org Sun Sep 10 05:20:33 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 10 Sep 2006 01:20:33 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 100522 SWODY2 SPC AC 100521 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 AM CDT SUN SEP 10 2006 VALID 111200Z - 121200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... LATEST SHORT-RANGE MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT IN EVOLUTION OF MID/UPPER-LEVEL TROUGH OVER THE MIDWEST INTO UPPER MS VALLEY. THIS FEATURE...CURRENTLY COMPOSED OF SEVERAL SMALLER PERTURBATIONS OVER KS AND NEB...IS FORECAST TO PHASE WITH NRN BRANCH IMPULSES OVER BRITISH COLUMBIA AND SASKATCHEWAN/MANITOBA...EFFECTIVELY FORMING A LARGER-SCALE TROUGH DURING THE DAY TWO PERIOD. IN THE LOW-LEVELS...ATTENDANT SURFACE LOW WILL DEVELOP GENERALLY EWD ACROSS CNTRL MO INTO CNTRL IL WHILE TRAILING COLD FRONT PUSHES SWD INTO THE LOWER MS VALLEY AND CNTRL TX. A WEAK WARM OR STATIONARY FRONT WILL EXTEND EWD FROM THIS LOW ACROSS THE OH VALLEY. ...OH VALLEY INTO OZARK PLATEAU... IT APPEARS CONSIDERABLE CLOUDS AND PRECIPITATION WILL LIKELY PERSIST THROUGH MUCH OF THE PERIOD FROM VICINITY OF SURFACE LOW EWD ALONG WARM FRONT OWING TO STRONG DEEP-LAYER FORCING VIA LOW-LEVEL WAA AND DCVA AHEAD OF EVOLVING UPPER TROUGH. BETTER POTENTIAL FOR AIR MASS DESTABILIZATION WILL LIKELY OCCUR ACROSS PRE-COLD FRONTAL WARM SECTOR --I.E. CNTRL/SRN PARTS OF MO/IL-- WHERE STRONGER DIABATIC HEATING WILL COMBINE WITH DEWPOINTS IN THE 60S TO SUPPORT MLCAPES OF 1000-1500 J/KG. EXPECT TSTMS TO INCREASE IN COVERAGE AND INTENSITY THROUGH THE AFTERNOON AS FORCING ASSOCIATED WITH UPPER TROUGH AND SURFACE FRONT ENCOUNTER DESTABILIZING AIR MASS. NEITHER VERTICAL SHEAR NOR MID-LEVEL LAPSE RATES ARE FORECAST TO BE PARTICULARLY STRONG AND THIS SHOULD TEND TO LIMIT UPDRAFT STRENGTH/STORM ORGANIZATION. STILL...THE PRESENCE OF RELATIVELY STEEP LOW-LEVEL LAPSE RATES AND MODEST INSTABILITY MAY SUPPORT A FEW MARGINALLY SEVERE STORMS CAPABLE OF STRONG WINDS AND SOME HAIL. STRONGER LOW AND DEEP-LAYER SHEAR WILL LIKELY EXIST NEAR SURFACE LOW EWD ALONG WARM FRONT. HOWEVER...IT APPEARS THAT INSTABILITY WILL REMAIN QUITE MARGINAL OWING TO THE PERSISTENT CLOUDS/PRECIPITATION. ...SRN PLAINS... DIURNAL STRONG STORMS WILL BE POSSIBLE MONDAY AFTERNOON INTO EVENING BOTH ALONG COLD FRONT AS WELL AS IN POST-FRONTAL UPSLOPE OVER CNTRL/ERN NM WITHIN UNSTABLE AIR MASS WITH MLCAPES OF 500-1500 J/KG. HERE TOO...VERTICAL SHEAR WILL REMAIN RELATIVELY WEAK...WITH THE EXCEPTION BEING OVER CNTRL/ERN NM WHERE BACKED LOW-LEVEL WINDS WILL RESULT IN EFFECTIVE BULK SHEAR APPROACHING 30 KTS. LOCALLY STRONG WIND GUSTS WILL BE POSSIBLE WITH THE MOST INTENSE STORMS OVER THE LOWER ELEVATIONS...WHILE THE THREAT OF MARGINALLY SEVERE HAIL WILL EXIST WITH THE STRONGER CELLS DEVELOPING OVER THE HIGH PLAINS. ..MEAD.. 09/10/2006  From swody2 at goshenarc.org Sun Sep 10 17:24:52 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Sun, 10 Sep 2006 13:24:52 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 101726 SWODY2 SPC AC 101726 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1226 PM CDT SUN SEP 10 2006 VALID 111200Z - 121200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE SYNOPTIC PATTERN WILL FEATURE BUILDING HEIGHTS ACROSS MUCH OF WRN CONUS...EXCEPT FOR REGIME OF ZONAL NRN STREAM FLOW ACROSS PACIFIC NW. SHORTWAVE TROUGH NOW ANALYZED OVER SRN ALTA IS FCST TO DIG SSEWD OVER NRN HIGH PLAINS...REACHING CENTRAL HIGH PLAINS BY 12/12Z. DOWNSTREAM...BROAD/WEAK MID/UPPER LEVEL LOW -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY AND PROFILER DATA OVER ERN NEB -- IS EXPECTED TO MOVE SLOWLY EWD ACROSS MID/UPPER MS VALLEY REGION. CONSIDERABLE DISAGREEMENT LINGERS AMONGST LATEST RUNS OF SHORT-RANGE DETERMINISTIC MODELS AND SREFX MEMBERS REGARDING PRECISE LOCATION OF CENTER BY 12/00Z AND THEREAFTER...AS WELL AS ASSOCIATED 60 M INTERVAL HEIGHT LINES AT 500 MB. HOWEVER....MOST PROGGED SCENARIOS AS WELL AS ENSEMBLE CONSENSUS FAVOR DIFFUSE/POSITIVELY-TILTED SHORTWAVE TROUGH EXTENDING SWWD FROM THIS LOW TO SRN HIGH PLAINS AT 12/00Z. AT SFC...WEAK FRONTAL-WAVE LOW -- NOW ANALYZED OVER S-CENTRAL NEB/N-CENTRAL KS -- SHOULD BE POSITIONED EARLY IN PERIOD INVOF NRN MO AND TAKE CYCLONICALLY CURVING TRACK ENEWD/NEWD ACROSS NERN MO/NRN IL. CONSIDERABLE PROGNOSTIC VARIATIONS ALSO EXIST IN STRENGTH/TRACK OF THIS FEATURE...WITH SPECTRAL BEING DEEPEST OUTLIER AND OPERATIONAL ETA/NGM APPROXIMATING WEAKEST EXTENT OF ENSEMBLE SPECTRUM. COLD FRONT SHOULD MOVE SEWD FROM SRN HIGH PLAINS...NRN OK...SERN KS POSITION AT 11/12Z TO NEAR AXIS FROM SERN MO...CENTRAL-ERN AR...S-CENTRAL TX BY 12/12Z. ...LOWER OH/MS VALLEY TO NE TX... SCATTERED TO WIDELY SCATTERED TSTMS ARE POSSIBLE BY MID-LATE AFTERNOON...IN WEAKLY CAPPED AIR MASS ALONG/AHEAD OF SFC COLD FRONT. POTENTIAL EXISTS FOR A FEW ORGANIZED MULTICELL CLUSTERS TO DEVELOP...MOST INTENSE CELLS PRODUCING STG-SVR GUSTS AND MRGLLY SVR HAIL. SEVERAL OFFSETTING FACTORS INDICATE AT LEAST MRGL POTENTIAL BUT ALSO PRECLUDE MORE ROBUST SVR PROBABILITIES ATTM. STRONGEST DIRECTIONAL SHEAR WILL EXIST INVOF SFC FRONTAL-WAVE LOW...WHERE SFC WINDS ARE RELATIVELY BACKED. HOWEVER WEAK MIDLEVEL FLOW -- I.E. 15-25 KT AT 500 MB OVER MUCH OF REGION -- WILL PREVENT STRONG DEEP-LAYER SHEAR FROM DEVELOPING. UPPER LEVEL FLOW WILL BE MAXIMIZED BENEATH BROAD SRN STREAM JET BRANCHES OVER OZARKS AND FROM TX ACROSS LOWER MS VALLEY...AIDING IN SHEAR THROUGH CLOUD-BEARING LAYER. WEAK DEEP-LAYER LAPSE RATES WILL LIMIT CAPE...AS WILL POTENTIAL CLOUD COVER AND PRECIP OVER MUCH OF THIS REGION. HOWEVER...POCKETS OF FAVORABLE DIURNAL HEATING MAY YIELD SHALLOW/WELL-MIXED BOUNDARY LAYERS MORE CONDUCIVE TO STG GUSTS...WHILE SFC DEW POINTS GENERALLY IN 60S F SUPPORT MLCAPES IN 1000-2000 J/KG RANGE. ...CENTRAL HIGH PLAINS... ISOLATED TO WIDELY SCATTERED TSTMS ARE POSSIBLE MAINLY FROM MIDAFTERNOON THROUGH EARLY EVENING...AS INSOLATION OPTIMALLY DESTABILIZES BOUNDARY LAYER OVER ERN MOUNTAINS AND ADJACENT FOOTHILLS AND HIGH PLAINS. MOISTURE WILL BE MORE LIMITED WITH NWD EXTENT. HOWEVER...LARGE SCALE ASCENT ASSOCIATED WITH MID-UPPER TROUGH OVER NRN/CENTRAL HIGH PLAINS MAY CONTRIBUTE ENOUGH DESTABILIZATION TO SUPPORT MRGL HAIL/WIND POTENTIAL AS FAR N AS VICINITY CO/WY BORDER. TSTMS SHOULD MOVE GENERALLY SWD WITH ANY SVR THREAT WEAKENING CONSIDERABLY AFTER SUNSET. ..EDWARDS.. 09/10/2006  From swody2 at goshenarc.org Mon Sep 11 05:25:43 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Mon, 11 Sep 2006 01:25:43 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 110527 SWODY2 SPC AC 110526 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1226 AM CDT MON SEP 11 2006 VALID 121200Z - 131200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LOWER OH VALLEY AND MID SOUTH... ...SYNOPSIS... UPPER TROUGH FROM THE UPPER GREAT LAKES INTO THE MIDDLE MS VALLEY WILL AMPLIFY THROUGH THE DAY TWO PERIOD AS EMBEDDED VORTICITY MAXIMA NOW OVER ERN ND/NWRN MN AND ERN MT PHASE AND DIG SEWD TOWARD THE CNTRL AND LOWER MS VALLEY. TO THE SW...VORTICITY MAXIMUM OVER CNTRL/SRN CA IS FORECAST TO BECOME PROGRESSIVELY CUT OFF FROM MEAN FLOW WITH THIS FEATURE REMAINING NEARLY STATIONARY OVER SRN PARTS OF CA/AZ INTO BAJA AND THE NRN GULF OF CA. IN THE LOW-LEVELS...PRIMARY SURFACE LOW ASSOCIATED WITH CNTRL U.S. TROUGH WILL DEVELOP NEWD FROM CNTRL OR SRN IL INTO LOWER MI BY WEDNESDAY MORNING. ATTENDANT COLD FRONT WILL SLOWLY PUSH EWD THROUGH THE CNTRL/SRN MS VALLEY WITH A SECONDARY SURFACE LOW DEVELOPING ON THIS BOUNDARY ALONG THE GULF COAST. ...LOWER OH VALLEY INTO MID SOUTH... LATEST SHORT RANGE MODEL GUIDANCE REMAINS CONSISTENT IN INDICATING THAT THE STRONGEST LARGE-SCALE FORCING FOR ASCENT /12-HR 500 MB HEIGHT FALLS OF 30-60 M/ WILL OCCUR ACROSS SLIGHT RISK AREA LATE TUESDAY AFTERNOON INTO TUESDAY NIGHT...FOCUSING STRONG TO SEVERE STORMS ALONG AND AHEAD OF COLD FRONT. IT APPEARS THAT CLUSTERS OF TSTMS WILL PERSIST THROUGH MUCH OF THE PERIOD AHEAD OF SURFACE FRONT FROM THE OH VALLEY SWD INTO THE MID SOUTH...DRIVEN BY DEEP-LAYER FORCING AHEAD OF DIGGING TROUGH. WHILE MID-LEVEL LAPSE RATES WILL REMAIN RELATIVELY WEAK AND NEAR MOIST ADIABATIC...MOIST BOUNDARY LAYER CONDITIONS AND DIURNAL HEATING WILL CONTRIBUTE TO POCKETS OF MODERATE INSTABILITY WITH MLCAPES APPROACHING 1000-1500 J/KG. THE MOST INTENSE STORM DEVELOPMENT WILL LIKELY OCCUR DURING THE MID TO LATE AFTERNOON HOURS NEAR OR JUST W OF THE MS RIVER AS STRONGER FORCING ASSOCIATED WITH ABOVEMENTIONED...DIGGING VORTICITY MAXIMA BEGIN TO OVERSPREAD FRONTAL ZONE AND WRN EDGE OF INSTABILITY AXIS. INCREASING MID AND UPPER-LEVEL FLOW WILL RESULT IN 30-35 KTS OF EFFECTIVE BULK SHEAR...SUFFICIENT FOR ORGANIZED MULTICELL CLUSTERS AND MARGINAL SUPERCELL/BOW STRUCTURES CAPABLE OF MAINLY DAMAGING WINDS AND SOME SEVERE HAIL. AN ISOLATED TORNADO THREAT MAY EXIST NEAR THE GULF COAST ALONG TRACK OF SECONDARY SURFACE LOW. WHILE DEEP-LAYER SHEAR WILL NOT BE PARTICULARLY STRONG...MODEST LOW-LEVEL SHEAR COUPLED WITH VERY MOIST BOUNDARY LAYER CONDITIONS MAY SUPPORT PERIODIC UPDRAFT ROTATION WITH A THREAT OF A BRIEF TORNADO OR TWO. ...SRN AZ... TSTMS ARE FORECAST TO BECOME INCREASINGLY WIDESPREAD TUESDAY AFTERNOON INTO TUESDAY NIGHT ALONG THE NRN INFLUENCE OF QUASI-STATIONARY UPPER LOW. HERE...STEEP LAPSE RATES WILL COMBINE WITH BOUNDARY LAYER DEWPOINTS IN THE 50S TO SUPPORT MLCAPES OF AROUND 1000 J/KG. FORECAST SOUNDINGS INDICATE ELY LOW-LEVEL FLOW VEERING TO WLY IN THE UPPER TROPOSPHERE WITH GENERALLY 20-25 KTS OF DEEP-LAYER SHEAR. WHILE THIS SHEAR MAY LIMIT THE OVERALL SEVERE WEATHER THREAT...THE STEEP LAPSE RATES AND DEEPLY MIXED BOUNDARY LAYER CONDITIONS INDICATE THE POTENTIAL FOR LOCALLY STRONG WIND GUSTS AND SOME MARGINALLY SEVERE HAIL WITH THE STRONGEST STORMS. ..MEAD.. 09/11/2006  From swody2 at goshenarc.org Wed Sep 13 05:20:30 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 13 Sep 2006 01:20:30 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 130522 SWODY2 SPC AC 130521 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 AM CDT WED SEP 13 2006 VALID 141200Z - 151200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... FURTHER INTENSIFICATION OF LONG WAVE TROUGH WILL OCCUR OVER THE WRN U.S. AS STRONG MID AND UPPER-LEVEL JET STREAKS DIG SEWD TOWARD THE GREAT BASIN FROM THE NERN PACIFIC. AS THIS OCCURS...UPPER LOW NOW OVER SRN AZ/NRN SONORA MEXICO WILL EJECT NEWD INTO THE HIGH PLAINS REGION. IN THE E...CONTINUED WEAKENING OF MID-LEVEL TROUGH WILL OCCUR AS IT APPROACHES THE ATLANTIC COAST. IN THE LOW-LEVELS...LEE CYCLONE OVER NERN WY WILL DEVELOP NEWD INTO WRN OR CNTRL ND WITH ATTENDANT COLD FRONT PUSHING SEWD THROUGH THE PACIFIC NW AND NRN ROCKIES. LEE TROUGH WILL CONCURRENTLY STRENGTHEN OVER THE HIGH PLAINS REGION. MEANWHILE IN THE E...PRIMARY SURFACE LOW OVER SERN GA WILL DEVELOP NEWD ALONG THE SC COAST BEFORE MOVING OFFSHORE WITH ASSOCIATED COLD FRONT PUSHING EWD THROUGH THE PIEDMONT AND COASTAL PLAIN...AND MOST OF THE FL PENINSULA. ...FL PENINSULA NEWD ALONG THE CAROLINA COASTS... TSTMS WILL LIKELY BE ONGOING THURSDAY MORNING IN ADVANCE OF SURFACE LOW AND COLD FRONT WITHIN A MOIST AND WEAKLY CAPPED AIR MASS. VERTICAL SHEAR WILL BE STRONGEST ALONG THE CAROLINA COASTS OWING TO BACKED LOW-LEVEL WINDS AHEAD OF SURFACE LOW...THOUGH THE MARGINAL INSTABILITY SHOULD LIMIT THE POTENTIAL FOR LONGER-LIVED...ORGANIZED UPDRAFTS. FARTHER TO THE S OVER THE CNTRL AND SRN FL PENINSULA... AIR MASS IS EXPECTED TO BECOME MODERATELY UNSTABLE...HOWEVER VERTICAL SHEAR WILL WEAKEN CONSIDERABLY WITH SWD EXTENT. A FEW STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE THROUGH THE MORNING AND AFTERNOON HOURS WITH THE MAIN THREAT BEING LOCALLY STRONG WIND GUSTS. THIS THREAT APPEARS TOO MINIMAL TO WARRANT A SLIGHT RISK. ...FOUR-CORNERS REGION... TSTMS ARE FORECAST TO BECOME INCREASINGLY NUMEROUS THURSDAY AFTERNOON AS LARGE-SCALE FORCING FOR ASCENT IN LEFT EXIT REGION OF APPROACHING UPPER-LEVEL JET STREAK OVERSPREADS REGION. LOW-LEVEL MOISTURE WILL BE MARGINAL THOUGH THE PRESENCE OF RELATIVELY STEEP LOW TO MID-LEVEL LAPSE RATES WILL RESULT IN A MARGINALLY UNSTABLE ENVIRONMENT. THE STRONGEST STORMS WILL BE CAPABLE OF SOME HAIL AND STRONG WIND GUSTS THROUGH THURSDAY EVENING. ..MEAD.. 09/13/2006  From swody2 at goshenarc.org Wed Sep 13 14:04:18 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 13 Sep 2006 10:04:18 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 121738 SWODY2 SPC AC 121737 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1237 PM CDT TUE SEP 12 2006 VALID 131200Z - 141200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE SYNOPTIC PATTERN WILL FEATURE HEIGHT FALLS LATE DAY-2 ACROSS PACIFIC NW AND NRN ROCKIES...ACCOMPANIED BY SEWD SHIFT OF UPPER RIDGING FROM NRN ROCKIES TO SRN/CENTRAL PLAINS. AS THIS OCCURS...DOWNSTREAM UPPER LOW -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER MN/IA BORDER -- IS EXPECTED TO TURN SEWD THEN EWD BETWEEN OH VALLEY AND GREAT LAKES. THIS FEATURE SHOULD EVOLVE TO OPEN-WAVE TROUGH IN PHASE WITH PREVIOUSLY DETACHED SHORTWAVE NOW DIGGING SEWD ACROSS NERN NM AND TX PANHANDLE. BY END OF PERIOD...COMBINED TROUGH SHOULD EXTEND FROM ERN GREAT LAKES SWWD TO CENTRAL GULF COAST. ASSOCIATED SFC LOW -- NOW ANALYZED INVOF IL/WI BORDER -- IS FCST TO MOVE NEWD ACROSS SRN PORTIONS ONT/QUE DAY-2...AS TRAILING COLD FRONT MOVES SEWD OVER TN VALLEY...SRN APPALACHIANS...AND PORTIONS FL PANHANDLE. OPERATIONAL/DETERMINISTIC MODELS AND MANY SREFX MEMBERS NOW INDICATE DEVELOPMENT OF WEAK FRONTAL-WAVE LOW BY EARLY IN PERIOD ACROSS AL...SUBSEQUENTLY MOVING EWD OR NEWD ACROSS GA...POTENTIALLY LINKING WITH DAMMING/PIEDMONT FRONT. PROGS ARE QUITE INCONSISTENT WITH STRENGTH OF THIS FEATURE THROUGHOUT PERIOD...AND WITH TRACK AFTER ABOUT 14/00Z. ...OH VALLEY...LOWER GREAT LAKES REGION... BAND OF TSTMS MAY DEVELOP LATE MORNING INTO AFTERNOON AND MOVE ENEWD ACROSS THIS AREA. MAIN CONCERN ATTM IS AMOUNT/EXTENT OF FAVORABLE INSTABILITY...GIVEN LIKELIHOOD OF AMBIENT CLOUD COVER LIMITING SFC DIABATIC HEATING...AND MIDLEVEL LAPSE RATES JUST SLGTLY GREATER THAN MOIST ADIABATIC. NNE-SSW ORIENTED CORRIDOR OF LARGE SCALE ASCENT -- NEARLY PARALLEL TO FRONT AND JUST AHEAD OF MID-UPPER TROUGH -- SHOULD ENHANCE LAPSE RATES JUST ENOUGH TO SUPPORT SOME SFC-BASED BUOYANCY...PROBABLY AOB 500 J/KG MOST AREAS. DEEP-LAYER WIND PROFILES WILL BE LARGELY UNIDIRECTIONAL WITH WEAK COMPONENT OF MEAN FLOW ACROSS POTENTIAL FORCING BOUNDARY. THEREFORE SVR POTENTIAL APPEARS TOO CONDITIONAL/MRGL FOR CATEGORICAL OUTLOOK ATTM. ...SERN CONUS... SCATTERED TSTMS ARE LIKELY THROUGH MUCH OF PERIOD ACROSS THIS REGION...AMIDST REGIME OF LOW LEVEL WAA AND INCREASINGLY RICH MOISTURE. SOME OF THESE MAY BECOME SUPERCELLS WITH POTENTIAL FOR MRGL HAIL...DAMAGING GUST OR BRIEF TORNADO. WITH CINH EXPECTED TO BE WEAK...AFTERNOON/EARLY EVENING CONVECTION MAY BECOME SFC BASED...WITH STRONG INSOLATION IN ANY RELATIVELY CLOUD-FREE AREAS HELPING TO OFFSET WEAK MIDLEVEL LAPSE RATES FOR MLCAPE POTENTIALLY NEAR 1000 J/KG. MEANWHILE...INCREASING MIDLEVEL GRADIENT WINDS AHEAD OF MID-UPPER TROUGH WILL ENHANCE 0-6 KM SHEAR...PARTICULARLY OVER INLAND AREAS AL/GA/SC. MEANWHILE POTENTIAL EXISTS FOR BACKED SFC FLOW INVOF SFC LOW...CONTRIBUTING TO MESOSCALE AREA OF ENLARGED 0-3 KM AGL HODOGRAPHS. CONSIDERABLE UNCERTAINTY EXISTS ABOUT STRENGTH OF HEATING/DESTABILIZATION...AND AS MENTIONED ABOVE...REGARDING TRACK/STRENGTH OF WAVE LOW. THEREFORE WILL KEEP TOTAL SVR PROBABILITIES MRGL ATTM UNTIL MESOSCALE FOCI BECOME BETTER DEFINED. ...SWRN CONUS... MID-UPPER LEVEL LOW NOW EVIDENT OVER SWRN AZ IS FCST TO MEANDER ERRATICALLY ACROSS SRN AZ/NWRN SONORA REGION THROUGH PERIOD. ASSOCIATED NW-SE ORIENTED SFC TROUGH -- CONTAINING ONE OR MORE WEAK LOWS -- SHOULD HELP TO MAINTAIN FETCH OF MOISTENING FLOW FROM SE...IN LOW-MIDDLE LEVELS. STEEP DEEP-LAYER LAPSE RATES ARE POSSIBLE WHEN DIURNAL HEATING IS COMBINED WITH MIDLEVEL COOLING ASSOCIATED WITH CYCLONE ALOFT. CLOUDS/PRECIP AND CONVECTIVE STABILIZATION -- RESULTING FROM DAY-1 ACTIVITY -- MAY LIMIT OR FOCUS POTENTIAL ON MESOSCALE. STRONGEST STORMS MAY PRODUCE HAIL/GUSTS NEAR SVR LEVELS. ..EDWARDS.. 09/12/2006  From swody2 at goshenarc.org Tue Sep 19 05:34:29 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 19 Sep 2006 01:34:29 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 190535 SWODY2 SPC AC 190534 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1234 AM CDT TUE SEP 19 2006 VALID 201200Z - 211200Z ...NO SVR TSTM AREAS FORECAST... ...CENTRAL PLAINS... IMPRESSIVE HEIGHT FALLS...ON THE ORDER OF 180-200M DURING THE LATTER HALF OF THE PERIOD...WILL DEVELOP ACROSS THE CNTRL PLAINS WEDNESDAY NIGHT AS A STRONG SPEED MAX DIGS INTO NRN NM...THEN EJECTS NEWD INTO CNTRL KS. THIS FEATURE WILL REQUIRE RAPID ADJUSTMENT AT LOW LEVELS...IN THE LEE OF THE ROCKIES...WHERE DEEPENING SFC CYCLOGENESIS IS EXPECTED ACROSS CO INTO NRN KS/SRN NEB BY 21/12Z. FOCUSED ASCENT DUE TO STRONG LOW LEVEL WAA...AND VORTICITY ADVECTION...WILL RESULT IN STEEPENING LAPSE RATES AND MOISTENING PROFILES ABOVE THE BOUNDARY LAYER AFTER 00Z ACROSS MUCH OF NEB...SWD ACROSS KS INTO NWRN OK. DESPITE A LAG IN BOUNDARY LAYER MOISTURE RETURN INTO THIS REGION...FORECAST SOUNDINGS AND STRENGTH OF UPPER SYSTEM SUGGEST STRONG ELEVATED THUNDERSTORMS ARE POSSIBLE AFTER DARK. MEAGER INSTABILITY WILL BE THE LIMITING FACTOR FOR WIDESPREAD SEVERE...ALTHOUGH A FORCED LINE OF THUNDERSTORMS SHOULD DEVELOP AND PRODUCE AT LEAST MARGINALLY SEVERE HAIL...WITH POSSIBLE LARGER STONES IN ISOLATED LOCATIONS. ..DARROW.. 09/19/2006  From swody2 at goshenarc.org Tue Sep 19 17:31:15 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Tue, 19 Sep 2006 13:31:15 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 191732 SWODY2 SPC AC 191731 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1231 PM CDT TUE SEP 19 2006 VALID 201200Z - 211200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... STRONGER TROUGH/UPPER LOW INITIALLY FORECAST OVER THE GREAT BASIN WILL MOVE SEWD ACROSS THE ROCKIES TOWARD THE SRN HIGH PLAINS THIS PERIOD. ASSOCIATED SURFACE LOW WILL ALSO MOVE OUT OF THE ROCKIES INTO THE HIGH PLAINS...WHERE A MAINLY NOCTURNAL/ELEVATED CONVECTIVE EVENT IS EXPECTED. ELSEWHERE...THUNDERSTORMS ARE EXPECTED OVER CENTRAL AND SRN FL...WITH A STABLE ATMOSPHERE ACROSS THE REMAINDER OF THE CONUS LIKELY PRECLUDING APPRECIABLE THUNDER THREAT. ...CENTRAL PLAINS... SLY LOW-LEVEL FLOW IS FORECAST ACROSS THE PLAINS AS SURFACE LOW MOVES EWD ACROSS THE ROCKIES TOWARD THE PLAINS. HOWEVER...RELATIVELY DRY BOUNDARY LAYER WILL PERSIST AS RICHER MOISTURE REMAINS OVER THE GULF S OF MAIN BAROCLINIC ZONE. THEREFORE...EXPECT LIMITED DESTABILIZATION AND A CAPPED BOUNDARY LAYER TO PERSIST THROUGH THE DAY ACROSS THE PLAINS...SUPPRESSING MOST IF NO ALL CONVECTIVE DEVELOPMENT. HOWEVER...LOW-LEVEL JET WILL DEVELOP DURING THE EVENING...IN RESPONSE TO APPROACHING UPPER TROUGH. WITH STEEP LAPSE RATES SPREADING EWD ABOVE LOW-LEVEL WARMING/MOISTENING...EXPECT ELEVATED STORMS TO DEVELOP. SUFFICIENTLY STRONG/VEERING WIND FIELD SHOULD COMBINE WITH RELATIVELY STEEP LAPSE RATES ALOFT TO SUPPORT A FEW STRONGER STORMS -- AND ASSOCIATED THREAT FOR ISOLATED HAIL. ..GOSS.. 09/19/2006  From swody2 at goshenarc.org Wed Sep 20 05:44:53 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 20 Sep 2006 01:44:53 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 200545 SWODY2 SPC AC 200545 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1245 AM CDT WED SEP 20 2006 VALID 211200Z - 221200Z ...NO SVR TSTM AREAS FORECAST... ...CENTRAL PLAINS/LOWER MO VALLEY... EARLY MORNING WV IMAGERY SUPPORTS LATEST MODEL GUIDANCE REGARDING UPPER LOW OVER ORE...DIGGING SEWD INTO THE GREAT BASIN. THIS FEATURE WILL MOVE ACROSS THE CNTRL ROCKIES INTO KS BY 12Z THURSDAY MORNING WHERE SUBSEQUENT STRONG HEIGHT FALLS AND EJECTING SPEED MAX WILL ALLOW UPPER LOW TO LIFT NEWD INTO WRN IA LATE IN THE OVERNIGHT PERIOD. DESPITE RELUCTANCE OF BOUNDARY LAYER MOISTURE TO RETURN ACROSS THE WARM SECTOR AHEAD OF CYCLONE...IT APPEARS STRONG ASCENT AND STEEP LAPSE RATES NORTH OF JET AXIS WILL CONTRIBUTE GREATLY TO THE INSTABILITY REQUIRED FOR LOW-TOPPED CONVECTION AHEAD OF COLD FRONT BY 18Z. EARLY MORNING ACTIVITY MAY ACTUALLY BE ELEVATED IN NATURE...DRIVEN IN LARGE PART DUE TO WARM ADVECTION ATOP THE CAPPED BOUNDARY LAYER. HOWEVER...IT APPEARS DAYTIME HEATING BENEATH COMPACT...AND NEARLY VERTICALLY STACKED...LOW WILL ALLOW AIRMASS TO DESTABILIZE ALONG A NARROW AXIS...AND WITHIN A BRIEF TIME FRAME FOR SFC-BASED THUNDERSTORMS ACROSS MUCH OF ERN KS/SERN NEB. STRONG SHEAR WOULD CERTAINLY SUPPORT STORM ROTATION. AT THIS TIME WILL MAINTAIN LOW PROBABILITIES FOR LOW-TOPPED SUPERCELLS GIVEN THE MEAGER MOISTURE/INSTABILITY EXPECTED. HOWEVER...THIS AREA WILL BE MONITORED FOR A POSSIBLE MESOSCALE-TYPE SEVERE RISK CLOSER TO THE EVENT. ..DARROW.. 09/20/2006  From swody2 at goshenarc.org Wed Sep 20 17:37:25 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 20 Sep 2006 13:37:25 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 201738 SWODY2 SPC AC 201737 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1237 PM CDT WED SEP 20 2006 VALID 211200Z - 221200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... VERY STRONG/PROGRESSIVE UPPER LOW IS FORECAST TO MOVE ACROSS THE CENTRAL AND SRN PLAINS THIS PERIOD...ACCOMPANIED BY VERY STRONG LOWER AND MID TROPOSPHERIC FLOW. ACCOMPANYING SURFACE LOW INITIALLY OVER ERN CO/WRN KS SHOULD MOVE SLOWLY EWD ACROSS KS...THOUGH LEE TROUGHING AND EVENTUAL CYCLOGENESIS ARE FORECAST TO PERSIST ACROSS ERN CO AHEAD OF NEXT SHORT-WAVE TROUGH AS IT ROTATES RAPIDLY SEWD INTO CO LATE. MAIN CONVECTIVE THREAT THIS PERIOD WILL EXIST OVER THE CENTRAL CONUS. HOWEVER...SEVERE POTENTIAL ACROSS THIS REGION REMAINS HIGHLY CONDITIONAL UPON DEGREE OF LOW-LEVEL MOISTURE ADVECTION AND ASSOCIATED AIRMASS DESTABILIZATION AHEAD OF SURFACE TROUGH/DRY LINE OVER KS/OK/N TX DURING THE DAY. ...SRN NEB SWD INTO N TX AND EWD INTO WRN MO/WRN AR... ELEVATED CONVECTION SHOULD BE ONGOING AT THE START OF THE PERIOD WITHIN REGION OF STRONG WARM ADVECTION. SURFACE TROUGH/DRYLINE IS FORECAST TO MOVE EWD ACROSS KS/OK/N TX THIS PERIOD...AS VERY STRONG KINEMATICS OVERSPREAD THE REGION AHEAD OF POTENT UPPER SYSTEM. MID-LEVEL JET STREAK NEAR 80 KT IS FORECAST...ABOVE 50 TO 60 KT SLY LOW-LEVEL JET. RESULTING SHEAR WOULD BE VERY SUPPORTIVE OF SUPERCELLS...AND ACCOMPANYING SEVERE/TORNADO THREAT. HOWEVER...POTENTIAL FOR DEEP/SURFACE-BASED CONVECTIVE DEVELOPMENT REMAINS HIGHLY CONDITIONAL ATTM...AS RICH BOUNDARY-LAYER MOISTURE REMAINS S OF BAROCLINIC ZONE ACROSS THE CENTRAL GULF. LATEST NAM/GFS AS WELL AS SREF GUIDANCE ALL INDICATE VERY MEAGER BOUNDARY LAYER MOISTURE RETURN AND ASSOCIATED AIRMASS DESTABILIZATION AHEAD OF SURFACE TROUGH AS IT SHIFTS RAPIDLY ACROSS THE REGION THROUGH THE AFTERNOON. GIVEN THESE QUESTIONS...WILL MAINTAIN A 5% SEVERE PROBABILITY ATTM. HOWEVER...AN UPGRADE IN RISK LEVEL MAY BE NEEDED...AS CERTAINTY REGARDING DEGREE OF LOW-LEVEL MOISTURE RETURN AND ASSOCIATED DESTABILIZATION INCREASES WITH TIME. ..GOSS.. 09/20/2006  From swody2 at goshenarc.org Thu Sep 21 05:36:42 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Thu, 21 Sep 2006 01:36:42 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 210537 SWODY2 SPC AC 210536 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1236 AM CDT THU SEP 21 2006 VALID 221200Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM SERN KS/ERN OK...NEWD INTO CNTRL IL... ...LOWER/MID MS VALLEY...SERN KS/ERN OK... LATE EVENING MODEL GUIDANCE CONTINUE WITH DIVERGENT SOLUTIONS IN REGARDS TO THE EVOLUTION OF MID U.S. UPPER TROUGH. IT APPEARS THE NAM MODEL IS TOO AGGRESSIVE MAINTAINING DOMINANCE OF LEAD UPPER LOW OVER THE MID MO VALLEY AT THE EXPENSE OF STRONG UPSTREAM SPEED MAX DIGGING INTO THE 4-CORNERS REGION. GFS HAS BEEN VERY CONSISTENT MAINTAINING TWO DISTINCT UPPER LOW/SHORTWAVE TROUGHS THROUGH THE PERIOD. LATEST THINKING IS THE LEAD SYSTEM WILL ROTATE NEWD INTO THE GREAT LAKES BY 18Z FRI WITH TRAILING WARM CONVEYOR BELT AND LLJ ACROSS THE MID MS VALLEY REGION EXPECTED TO GRADUALLY WEAKEN...BUT REMAIN THE FOCUS FOR POTENTIAL SCATTERED THUNDERSTORM DEVELOPMENT THROUGH THE PERIOD. OF MUCH MORE CONCERN IS THE SPEED MAX THAT WILL EJECT ACROSS THE SRN ROCKIES INTO KS DURING THE LATTER HALF OF THE PERIOD. THIS UPSTREAM SPEED MAX SHOULD INDUCE LEE CYCLOGENESIS OVER THE TX PANHANDLE WHICH WILL THEN LIFT NEWD ALONG SHARPENING WARM FRONT THAT WILL RETURN ACROSS THE SRN PLAINS IN THE WAKE OF LEAD SHORTWAVE. BOUNDARY LAYER MOISTURE SHOULD BE OF HIGH QUALITY ACROSS THE WARM SECTOR WITH UPPER 60S/LOWER 70S EXPECTED ACROSS THE SERN HALF OF THE SLIGHT RISK AREA. CONVECTIVE MODE/INITIATION WILL BE SOMEWHAT COMPLEX THROUGH THE PERIOD WITH WEAKENING LOW LEVEL WARM ADVECTION EXPECTED TO MAINTAIN THUNDERSTORM POTENTIAL FROM PORTIONS OF AR INTO IL THROUGH MUCH OF THE DAYLIGHT HOURS. SHEAR PROFILES WILL SUPPORT STORM ROTATION AND THERE APPEARS TO BE A THREAT FOR SUPERCELLS...HOWEVER WEAKENING LLJ THROUGH LATE AFTERNOON MAY LIMIT SEVERE POTENTIAL THROUGH PEAK HEATING. LATER IN THE EVENING...LLJ SHOULD BEGIN TO INCREASE ACROSS THE SRN PLAINS IN RESPONSE TO UPSTREAM SPEED MAX AND SFC WARM FRONT SHOULD LIFT NWD ACROSS ERN OK INTO SERN KS/SWRN MO. THIS SHARPENING BAROCLINIC ZONE WILL MOST LIKELY BE THE FOCUS FOR ROBUST SEVERE THUNDERSTORM DEVELOPMENT DURING THE OVERNIGHT HOURS. SHEAR PROFILES WILL BECOME INCREASINGLY FAVORABLE FOR SUPERCELLS...AND WITH SFC DEW POINTS EXPECTED TO RISE INTO THE LOWER 70S IT APPEARS THE TORNADO THREAT MAY ACTUALLY INCREASE AS WELL. WILL MONITOR THIS REGION FOR A POSSIBLE UPGRADE IN LATER OUTLOOKS. ..DARROW.. 09/21/2006  From swody2 at goshenarc.org Thu Sep 21 17:48:39 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Thu, 21 Sep 2006 13:48:39 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 211749 SWODY2 SPC AC 211748 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1248 PM CDT THU SEP 21 2006 VALID 221200Z - 231200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS ERN IA/SRN WI/NWRN INDIANA/IL/MO/NRN AR/NERN OK... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN UPPER GREAT LAKES REGION SSWWD INTO NERN TX... ...SYNOPSIS... UPPER SHORT-WAVE TROUGH FORECAST ACROSS THE MID MO VALLEY REGION AT THE START OF THE PERIOD SHOULD CONTINUE NWD...WHILE SECOND SHORT-WAVE TROUGH MOVES ESEWD ACROSS THE ROCKIES TOWARD THE CENTRAL PLAINS AROUND LARGER MID-LEVEL VORTEX. STRONG MID-LEVEL SPEED MAX ASSOCIATED WITH THIS TROUGH WILL SHIFT EWD ACROSS THE SRN ROCKIES/SRN PLAINS...AND INTO THE MID MO VALLEY REGION BY THE END OF THE PERIOD. AT THE SURFACE...MODELS DIFFER IN LOCATION OF PRIMARY SURFACE LOW DUE TO SMALLER-SCALE COMPLEXITY WITHIN THE LARGE UPPER TROUGH. HOWEVER...GENERAL AGREEMENT EXISTS THAT RICH BOUNDARY LAYER MOISTURE WILL SPREAD NWD ACROSS THE CENTRAL THIRD OF THE CONUS AHEAD OF AN EWD-MOVING COLD FRONT. COMBINATION OF RICH BOUNDARY LAYER MOISTURE SPREADING NWD BENEATH A VERY STRONG/FAVORABLY-VEERING WIND FIELD WITH HEIGHT SUGGESTS THAT A SIGNIFICANT/WIDESPREAD SEVERE WEATHER EVENT WILL UNFOLD THIS PERIOD. ...SRN PORTIONS OF THE UPPER GREAT LAKES SSWWD INTO NERN TX... CONVECTION IS FORECAST TO BE ONGOING AT THE START OF THE PERIOD ACROSS PARTS OF AR/MO/IL/IA AND VICINITY...IN CONJUCTION WITH STRONG/SLY LOW-LEVEL JET AND BROAD/ASSOCIATED ZONE OF WARM ADVECTION. ATTM...IT APPEARS THAT ONGOING STORMS SHOULD BE LARGELY SUB-SEVERE...EXCEPT POSSIBLY ACROSS AR ON LEADING EDGE OF RETURNING MOISTURE. THOUGH THIS ONGOING PRECIPITATION INJECTS A DEGREE OF UNCERTAINTY INTO THE DAY 2 FORECAST...MODELS GENERALLY AGREE THAT MOST OF THE CONVECTION SHOULD SHIFT N AND E WITH TIME...WHILE VERY MOIST BOUNDARY LAYER ADVECTS NWD ACROSS AN EXPANDING WARM SECTOR. ATTM...IT APPEARS THAT AT LEAST SOME DAYTIME HEATING WILL OCCUR ACROSS THE WARM SECTOR...RESULTING IN MODERATE DESTABILIZATION ACROSS THE MDT RISK AREA. THOUGH A STRONG MID-LEVEL FEATURE DOES NOT APPEAR LIKELY TO AFFECT THIS REGION...SMALLER/MORE SUBTLE FEATURES WILL MOVE NEWD IN SWLY FLOW AROUND SERN FRINGES OF LARGE/POSITIVELY-TILTED TROUGH. THIS SHOULD SUPPORT THE DEVELOPMENT ALONG PRIMARY LOW-LEVEL CONVERGENCE AXIS WHICH SHOULD BE MOVING ACROSS ERN KS/ERN OK INTO WRN MO AND NWRN AR DURING THE AFTERNOON. WITH THE LACK OF A PRONOUNCED SMALL-SCALE UPPER FEATURE...IT APPEARS ATTM THAT DISCRETE STORM DEVELOPMENT SHOULD OCCUR WITHIN POCKETS OF GREATER INSTABILITY. WITH VERY STRONG/WEAKLY DIFFLUENT SWLY FLOW ALOFT ABOVE VERY STRONG SSWLY LOW-LEVEL WIND FIELD...DEGREE OF SHEAR WILL ALLOW STORMS TO RAPIDLY ACQUIRE STRONG ROTATION. ALONG WITH THREAT FOR DAMAGING WINDS AND HAIL...MOIST BOUNDARY LAYER/LOW LCLS COMBINED WITH VERY STRONG LOW-LEVEL SHEAR WILL SUPPORT TORNADOES. THOUGH SOME UNCERTAINTY STILL EXISTS -- PARTICULARLY REGARDING EARLIER CONVECTION AND ITS EFFECT ON THE THERMODYNAMIC ENVIRONMENT...IT WOULD APPEAR THAT A SIGNIFICANT TORNADOES WILL BE POSSIBLE -- PARTICULARLY ACROSS MO AND INTO IL DURING THE AFTERNOON AND EVENING. LOW-LEVEL JET IS FORECAST TO FURTHER STRENGTHEN OVERNIGHT...WITH STRONGEST WARM ADVECTION FORECAST TO SHIFT NWD AND EWD INTO THE UPPER GREAT LAKES/OH VALLEY REGION. THOUGH THIS WILL LIKEWISE ALLOW CONVECTION -- AND SOME SEVERE THREAT -- TO EXPAND NWD AND EWD...MAIN THREAT SHOULD PERSIST FROM IL SSWWD...WHERE MOST FAVORABLE COMBINATION OF INSTABILITY AND SHEAR SHOULD REMAIN. ..GOSS.. 09/21/2006  From swody2 at goshenarc.org Thu Sep 21 19:29:39 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Thu, 21 Sep 2006 15:29:39 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 211930 SWODY2 SPC AC 211929 DAY 2 CONVECTIVE OUTLOOK RESENT 1 NWS STORM PREDICTION CENTER NORMAN OK 0229 PM CDT THU SEP 21 2006 VALID 221200Z - 231200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS ERN IA/SRN WI/NWRN INDIANA/IL/MO/NRN AR/NERN OK... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN UPPER GREAT LAKES REGION SSWWD INTO NERN TX... ...SYNOPSIS... UPPER SHORT-WAVE TROUGH FORECAST ACROSS THE MID MO VALLEY REGION AT THE START OF THE PERIOD SHOULD CONTINUE NWD...WHILE SECOND SHORT-WAVE TROUGH MOVES ESEWD ACROSS THE ROCKIES TOWARD THE CENTRAL PLAINS AROUND LARGER MID-LEVEL VORTEX. STRONG MID-LEVEL SPEED MAX ASSOCIATED WITH THIS TROUGH WILL SHIFT EWD ACROSS THE SRN ROCKIES/SRN PLAINS...AND INTO THE MID MO VALLEY REGION BY THE END OF THE PERIOD. AT THE SURFACE...MODELS DIFFER IN LOCATION OF PRIMARY SURFACE LOW DUE TO SMALLER-SCALE COMPLEXITY WITHIN THE LARGE UPPER TROUGH. HOWEVER...GENERAL AGREEMENT EXISTS THAT RICH BOUNDARY LAYER MOISTURE WILL SPREAD NWD ACROSS THE CENTRAL THIRD OF THE CONUS AHEAD OF AN EWD-MOVING COLD FRONT. COMBINATION OF RICH BOUNDARY LAYER MOISTURE SPREADING NWD BENEATH A VERY STRONG/FAVORABLY-VEERING WIND FIELD WITH HEIGHT SUGGESTS THAT A SIGNIFICANT/WIDESPREAD SEVERE WEATHER EVENT WILL UNFOLD THIS PERIOD. ...SRN PORTIONS OF THE UPPER GREAT LAKES SSWWD INTO NERN TX... CONVECTION IS FORECAST TO BE ONGOING AT THE START OF THE PERIOD ACROSS PARTS OF AR/MO/IL/IA AND VICINITY...IN CONJUCTION WITH STRONG/SLY LOW-LEVEL JET AND BROAD/ASSOCIATED ZONE OF WARM ADVECTION. ATTM...IT APPEARS THAT ONGOING STORMS SHOULD BE LARGELY SUB-SEVERE...EXCEPT POSSIBLY ACROSS AR ON LEADING EDGE OF RETURNING MOISTURE. THOUGH THIS ONGOING PRECIPITATION INJECTS A DEGREE OF UNCERTAINTY INTO THE DAY 2 FORECAST...MODELS GENERALLY AGREE THAT MOST OF THE CONVECTION SHOULD SHIFT N AND E WITH TIME...WHILE VERY MOIST BOUNDARY LAYER ADVECTS NWD ACROSS AN EXPANDING WARM SECTOR. ATTM...IT APPEARS THAT AT LEAST SOME DAYTIME HEATING WILL OCCUR ACROSS THE WARM SECTOR...RESULTING IN MODERATE DESTABILIZATION ACROSS THE MDT RISK AREA. THOUGH A STRONG MID-LEVEL FEATURE DOES NOT APPEAR LIKELY TO AFFECT THIS REGION...SMALLER/MORE SUBTLE FEATURES WILL MOVE NEWD IN SWLY FLOW AROUND SERN FRINGES OF LARGE/POSITIVELY-TILTED TROUGH. THIS SHOULD SUPPORT THE DEVELOPMENT ALONG PRIMARY LOW-LEVEL CONVERGENCE AXIS WHICH SHOULD BE MOVING ACROSS ERN KS/ERN OK INTO WRN MO AND NWRN AR DURING THE AFTERNOON. WITH THE LACK OF A PRONOUNCED SMALL-SCALE UPPER FEATURE...IT APPEARS ATTM THAT DISCRETE STORM DEVELOPMENT SHOULD OCCUR WITHIN POCKETS OF GREATER INSTABILITY. WITH VERY STRONG/WEAKLY DIFFLUENT SWLY FLOW ALOFT ABOVE VERY STRONG SSWLY LOW-LEVEL WIND FIELD...DEGREE OF SHEAR WILL ALLOW STORMS TO RAPIDLY ACQUIRE STRONG ROTATION. ALONG WITH THREAT FOR DAMAGING WINDS AND HAIL...MOIST BOUNDARY LAYER/LOW LCLS COMBINED WITH VERY STRONG LOW-LEVEL SHEAR WILL SUPPORT TORNADOES. THOUGH SOME UNCERTAINTY STILL EXISTS -- PARTICULARLY REGARDING EARLIER CONVECTION AND ITS EFFECT ON THE THERMODYNAMIC ENVIRONMENT...IT WOULD APPEAR THAT A SIGNIFICANT TORNADOES WILL BE POSSIBLE -- PARTICULARLY ACROSS MO AND INTO IL DURING THE AFTERNOON AND EVENING. LOW-LEVEL JET IS FORECAST TO FURTHER STRENGTHEN OVERNIGHT...WITH STRONGEST WARM ADVECTION FORECAST TO SHIFT NWD AND EWD INTO THE UPPER GREAT LAKES/OH VALLEY REGION. THOUGH THIS WILL LIKEWISE ALLOW CONVECTION -- AND SOME SEVERE THREAT -- TO EXPAND NWD AND EWD...MAIN THREAT SHOULD PERSIST FROM IL SSWWD...WHERE MOST FAVORABLE COMBINATION OF INSTABILITY AND SHEAR SHOULD REMAIN. ..GOSS.. 09/21/2006  From swody2 at goshenarc.org Fri Sep 22 05:59:11 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 22 Sep 2006 01:59:11 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 220600 SWODY2 SPC AC 220559 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1259 AM CDT FRI SEP 22 2006 VALID 231200Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-MS VALLEY...OH VALLEY...GREAT LAKES...OZARKS AND SRN PLAINS... ...MID-MS VALLEY/OZARKS/OH VALLEY/GREAT LAKES... AN IMPRESSIVE UPPER-LOW SHOULD BE IN THE NRN PLAINS SATURDAY MORNING WITH THE LOW FORECAST TO EJECT NEWD ACROSS THE UPPER MIDWEST SATURDAY AFTERNOON. SEVERAL STRONG TO POSSIBLY SEVERE MESOSCALE CONVECTIVE SYSTEMS SHOULD BE ONGOING AT THE BEGINNING OF THE PERIOD ALONG AND AHEAD OF A FRONTAL BOUNDARY EXTENDING SSWWD FROM A SFC LOW IN THE UPPER MIDWEST ACROSS IA INTO WRN MO AND ERN OK. SFC DEWPOINTS AHEAD OF THE BOUNDARY SHOULD BE IN THE UPPER 60S TO LOWER 70S F WHICH MAY RESULT IN WIDESPREAD MODERATE INSTABILITY ACROSS THE WARM SECTOR BY SATURDAY AFTERNOON. AS A RESULT...THUNDERSTORM COVERAGE SHOULD INCREASE ALONG AND AHEAD OF THE FRONT WITH SQUALL-LINE FORMATION LIKELY BY LATE AFTERNOON INTO THE EVENING ACROSS THE OH VALLEY...MID-MS VALLEY AND OZARKS. FORECAST SOUNDINGS SATURDAY AFTERNOON AND EVENING ACROSS THE REGION SHOW 0-6 KM SHEAR VALUES IN THE 50 TO 70 KT RANGE SUGGESTING SHEAR PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. THE LARGE NUMBER OF STORMS FORECAST IN THIS FAVORABLE WIND ENVIRONMENT SHOULD RESULT IN A MIXTURE OF STORM MODE WITH SUPERCELLS...BOW ECHOES AND SEVERE MULTICELLS ALL LIKELY. SUPERCELLS WILL BE MOST LIKELY IN AREAS OF ENHANCED INSTABILITY WHERE STORMS REMAIN DISCRETE. SUPERCELLS WILL ALSO BE POSSIBLE OUT AHEAD OF THE SQUALL-LINE OR ON THE SRN END OF CONVECTIVE LINES. SUPERCELLS AND BOW ECHOES WILL ALSO LIKELY BE EMBEDDED IN THE SQUALL-LINE. SEVERAL TORNADOES MAY OCCUR WITH SUPERCELLS AND/OR WITH THE STRONGER BOW ECHOES. THE TORNADO THREAT SHOULD BE THE GREATEST IN THE OH VALLEY ON THE NORTHWEST SIDE OF A 60 KT LOW-LEVEL JET WHERE LOW-LEVEL SHEAR SHOULD BE ENHANCED. THIS AREA IS ALSO FORECAST TO HAVE THE GREATEST LARGE-SCALE ASCENT ASSOCIATED WITH THE EJECTING UPPER-LOW. WIND DAMAGE AND LARGE HAIL WILL ALSO BE LIKELY WITH THE SUPERCELLS AND STRONGER BOWING SEGMENTS. THE LARGE NUMBER OF STORMS AND WIDESPREAD CLOUD COVER MAY INHIBIT DESTABILIZATION OVER SOME AREAS AND THE EXTENT OF DESTABILIZATION STILL REMAINS UNCERTAIN. IF IT APPEARS MODERATE INSTABILITY WILL BECOME WIDESPREAD WITH AN INTENSE SQUALL-LINE AND/OR A LARGE NUMBER OF RELATIVELY DISCRETE STORMS...THEN AN UPGRADE TO MODERATE RISK MAY BECOME NECESSARY IN LATER OUTLOOKS. ....SRN PLAINS... WEST TO SOUTHWEST FLOW ALOFT WILL IN BE IN PLACE ACROSS THE SRN PLAINS AHEAD OF AN APPROACHING UPPER-LEVEL TROUGH. MODEL FORECASTS DISAGREE ON WHETHER CONVECTIVE CLUSTERS WILL BE ONGOING AT THE BEGINNING OF THE PERIOD AHEAD OF A COLD FRONT LOCATED FROM ERN OK INTO CNTRL TX. MODEL FORECASTS DO AGREE WITH DEVELOPING MODERATE INSTABILITY ACROSS A WIDESPREAD AREA AHEAD OF THE FRONT IN CNTRL AND ERN TX. THIS SHOULD RESULT IN THUNDERSTORM INITIATION JUST ALONG AND JUST AHEAD OF THE BOUNDARY WITH THE DEVELOPMENT OF A SQUALL-LINE AND/OR A BROKEN LINE SEGMENT GRADUALLY ORGANIZING DURING THE AFTERNOON AND EARLY EVENING. FORECAST SOUNDINGS LATE SATURDAY AFTERNOON ACROSS THE REGION SHOW 0-6 KM SHEAR VALUES IN THE 35 TO 45 KT RANGE SUGGESTING SHEAR WILL BE ADEQUATE FOR ISOLATED SUPERCELLS AND SEVERE MULTICELLS ALONG AND AHEAD OF THE FRONT. ALTHOUGH LOW-LEVEL FLOW IS FORECAST TO BE STRONGER NORTHEAST OF THE REGION...AN ISOLATED TORNADO THREAT MAY STILL EXIST WITH THE STRONGER SUPERCELLS DURING THE LATE AFTERNOON AND EARLY EVENING. ISOLATED WIND DAMAGE AND LARGE HAIL WILL BE POSSIBLE WITH SUPERCELLS AND BOWING SEGMENTS ALONG THE CONVECTIVE LINE DURING THE AFTERNOON AND EVENING. ..BROYLES.. 09/22/2006  From swody2 at goshenarc.org Fri Sep 22 17:24:59 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Fri, 22 Sep 2006 13:24:59 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 221725 SWODY2 SPC AC 221724 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1224 PM CDT FRI SEP 22 2006 VALID 231200Z - 241200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES REGION SWWD INTO E TX... ...SYNOPSIS... LARGE/POSITIVELY-TILTED UPPER TROUGH IS FORECAST TO INITIALLY EXTEND FROM THE PLAINS INTO THE ROCKIES/GREAT BASIN...WITH A COLD FRONT MOVING EWD/SEWD ACROSS MO/CENTRAL OK/NRN AND WRN TX. FAIRLY SUBSTANTIAL DIFFERENCES EXIST BETWEEN THE NAM AND GFS HOWEVER...IN PROGRESSION OF THE SYNOPTIC-SCALE ENVIRONMENT THROUGH THE PERIOD. THE GFS IS FASTER THAN THE NAM WITH REGARDS TO THE EWD MOVEMENT OF THE UPPER TROUGH -- AND THEREFORE WITH THE ASSOCIATED COLD FRONTAL PROGRESSION. IN GENERAL HOWEVER...EXPECT THE UPPER TROUGH AND ASSOCIATED SURFACE FRONT TO PROGRESS EWD WITH TIME...WHILE MOIST WARM SECTOR AND STRONG FLOW ALOFT CONTINUE TO SUPPORT A FAIRLY SIGNIFICANT SEVERE THREAT -- LIKELY CENTERED ON THE MID MS/OH VALLEY REGION. ...GREAT LAKES/OH VALLEY REGION SWWD INTO E TX... STRONG/SEVERE STORMS SHOULD BE ONGOING AT THE START OF THE PERIOD...BOTH ALONG AND AHEAD OF COLD FRONT AS WELL AS ACROSS THE OH VALLEY/MIDWEST REGION IN WARM ADVECTION REGIME. THOUGH DEGREE OF DAYTIME DESTABILIZATION IS DIFFICULT TO DETERMINE ATTM DUE TO WIDESPREAD CLOUDS/PRECIPITATION...MOIST WARM SECTOR WILL LIKELY SUPPORT A SUFFICIENT THERMODYNAMIC ENVIRONMENT FOR A DIURNAL INCREASE IN STORM COVERAGE AND INTENSITY. GREATEST INSTABILITY IS EXPECTED TO DEVELOP FROM THE MID MS/LOWER OH VALLEY SSWWD...WHILE STRONGER KINEMATIC ENVIRONMENT SHOULD REMAIN FROM OK ENEWD INTO THE MIDWEST/OH VALLEY REGION. THEREFORE -- DESPITE DIFFERENCES IN TIMING AMONGST THE MODELS...MOST FAVORABLE COMBINATION OF SHEAR AND INSTABILITY SHOULD EXTEND FROM SERN OK ENEWD ACROSS THE OH VALLEY REGION. THEREFORE...WILL MAINTAIN HIGHEST PROBABILITY SEVERE THREAT ACROSS THIS REGION. GIVEN MOIST BOUNDARY LAYER AND STRENGTH OF SHEAR...TORNADO POTENTIAL WILL LIKELY EXIST ONCE AGAIN. HOWEVER...WITH SOMEWHAT MORE UNIDIRECTIONAL SWLY FLOW ALOFT...AND STRONGER LINEAR FORCING THIS PERIOD...DAMAGING WINDS WITH A MORE LINEAR CONVECTIVE MODE MAY PREVAIL ON DAY 2. ATTM...WILL NOT INTRODUCE MODERATE RISK -- PRIMARILY DUE TO MODEL DIFFERENCES WHICH MAKE HIGHLIGHTING THE MOST CONCENTRATED AREA OF SEVERE THREAT DIFFICULT ATTM. HOWEVER...LARGE-SCALE ENVIRONMENTAL FACTORS SUGGEST THAT AN UPGRADE TO MODERATE RISK MAY BE NECESSARY IN LATER OUTLOOKS. ..GOSS.. 09/22/2006  From swody2 at goshenarc.org Wed Sep 27 05:38:47 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 27 Sep 2006 01:38:47 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 270539 SWODY2 SPC AC 270538 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1238 AM CDT WED SEP 27 2006 VALID 281200Z - 291200Z ...NO SVR TSTM AREAS FORECAST... ...APPALACHIAN MTNS... A VIGOROUS UPPER-LEVEL TROUGH OVER THE UPPER MIDWEST TONIGHT WILL DIG QUICKLY SEWD INTO THE MS AND OH VALLEYS BY THE DAY 2 PERIOD. THE TROUGH IS FORECAST TO BECOME HIGHLY MERIDIONAL WITH A BAND OF VERY STRONG LARGE-SCALE ASCENT SPREADING SEWD ACROSS THE REGION AHEAD OF THE APPROACHING TROUGH. THIS COMBINED WITH STRONG LOW-LEVEL CONVERGENCE ALONG THE BOUNDARY SHOULD BE FAVORABLE FOR THUNDERSTORM DEVELOPMENT THURSDAY AFTERNOON. ALTHOUGH INSTABILITY SHOULD REMAIN MODEST THURSDAY...FORECAST SOUNDINGS SHOW STRONG WIND FIELDS ASSOCIATED WITH A 90 KT MID-LEVEL JET MAX ROUNDING THE BASE OF THE TROUGH. THIS SHOULD BE SUFFICIENT FOR AT LEAST A MARGINAL SEVERE THREAT IN THE CNTRL AND SRN APPALACHIAN MTNS THURSDAY AFTERNOON. THE GFS AND ECMWF AGREE WITH DEVELOPING A LINE OF CONVECTION IN THE APPALACHIANS WITH THE LINE MOVING ESEWD INTO THE APPALACHIAN FOOTHILLS ACROSS VA...NC AND SC THURSDAY EVENING. THE STRONG SHEAR AND FAST MOVEMENT OF THE UPPER-SYSTEM SHOULD BE FAVORABLE FOR STRONG WIND GUSTS WITH THE BETTER ORGANIZED LINE SEGMENTS. A PLUME OF STEEP MID-LEVEL LAPSE RATES SHOULD BE PRESENT AHEAD OF THE TROUGH MAKING HAIL ALSO POSSIBLE WITH THE STRONGER MULTICELL THUNDERSTORMS. ..BROYLES.. 09/27/2006  From swody2 at goshenarc.org Wed Sep 27 17:22:21 2006 From: swody2 at goshenarc.org (Severe Weather Outlook - Day 2) Date: Wed, 27 Sep 2006 13:22:21 -0400 Subject: [SWODY2] SWODY2 Message-ID: ACUS02 KWNS 271722 SWODY2 SPC AC 271721 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 PM CDT WED SEP 27 2006 VALID 281200Z - 291200Z ...NO SVR TSTM AREAS FORECAST... ...EASTERN APPALACHIANS... STRONG SPEED MAX WILL DIG SEWD ACROSS THE LOWER MO VALLEY INTO THE SRN APPALACHIANS BY EARLY EVENING WHERE 12HR HEIGHT FALLS SHOULD BE ON THE ORDER OF 120M. IT APPEARS THE ASSOCIATED FRONTAL ZONE WILL BE STRONGLY FORCED...AND CONVECTIVELY ACTIVE...AS IT PROGRESSES EWD ACROSS THE APPALACHIANS. A NARROW BAND OF THUNDERSTORMS SHOULD EVOLVE DURING THE LATE DAY1 PERIOD FROM THE OH VALLEY...SWWD INTO WRN TN. THIS ACTIVITY SHOULD ADVANCE INTO THE HIGHER ELEVATIONS OF WRN PA...SWWD INTO NRN GA EARLY IN THE PERIOD. AFTERNOON HEATING AHEAD OF WIND SHIFT SHOULD ENHANCE BOUNDARY LAYER INSTABILITY OVER AND TO THE LEE OF THE APPALACHIANS...ALTHOUGH FORECAST SOUNDINGS INDICATE SBCAPE VALUES SHOULD REMAIN GENERALLY IN THE 500-1000 J/KG RANGE. STRONG VERTICAL SHEAR CERTAINLY WOULD SUPPORT ORGANIZED UPDRAFTS...HOWEVER MARGINAL INSTABILITY AND LINEAR STORM MODE WITHIN WEAK MID LEVEL LAPSE RATE ENVIRONMENT SUGGEST MARGINALLY SEVERE WIND GUSTS WILL BE THE MAIN CONCERN WHERE BOUNDARY LAYER HEATING/BUOYANCY CAN DEVELOP AHEAD OF FRONTAL ZONE. ..DARROW.. 09/27/2006