[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 200605
SWODY1
SPC AC 200603

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0103 AM CDT SAT MAY 20 2006

VALID 201200Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS SERN KS TO COASTAL CAROLINAS...

...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF MT...

...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF WI...

...SYNOPSIS...
SYNOPTIC PATTERN WILL CONTINUE TO FEATURE WRN CONUS RIDGE AND ERN
TROUGH.  STRONG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL
IMAGERY OVER NRN MB -- IS FCST TO AMPLIFY AS IT MOVES SEWD TOWARD
MEAN TROUGH POSITION.  THIS SHOULD RESULT IN
SMALL...CLOSED...TIGHTLY DEFINED...MIDDLE-UPPER LEVEL LOW MOVING
SEWD ACROSS LS AND LH THROUGH PERIOD.  ASSOCIATED SFC COLD FRONT --
NOW PASSING SRN TIP OF LAKE MANITOBA AND MOVING SWWD ACROSS SRN SASK
-- IS FCST BY 21/00Z TO EXTEND FROM SSM AREA SWWD ACROSS IL/WI
BORDER REGION...THEN WWD ACROSS IA AND SRN SD...BECOMING
QUASISTATIONARY OVER SERN-N-CENTRAL MT.  FARTHER
S...PERSISTENT/QUASISTATIONARY FRONTAL ZONE WILL EXTEND FROM
CAROLINAS GENERALLY WWD ACROSS OZARKS TO SWRN KS/SERN CO.

MEANWHILE...AS MID/UPPER LEVEL CYCLONE SLOWLY PIVOTS EWD OFFSHORE
NRN CA/ORE...PERTURBATION NOW OVER CENTRAL/NRN CA WILL MOVE THROUGH
MEAN RIDGE POSITION ACROSS NRN ROCKIES.

...SERN KS TO TN VALLEY...
STRONG CAPPING SHOULD PRECLUDE DEVELOPMENT OVER MOST OR ALL OF WARM
SECTOR S OF FRONT...WITH POSSIBLE EXCEPTION OF INTENSELY
HEATED/MIXED BUT RELATIVELY DRY AIR MASS OVER SRN HIGH PLAINS. 
LARGEST PROBABILITIES FOR SVR WILL BE WITH LATE AFTERNOON THROUGH
EVENING DEVELOPMENT ALONG AND N OF SFC FRONT FROM SERN KS THROUGH TN
VALLEY REGION...MOVING SEWD THROUGH OVERNIGHT HOURS.  RELATIVE TO
AREAS FARTHER E...STEEPEST MIDLEVEL LAPSE RATES AND GREATEST
CONDITIONAL POTENTIAL FOR LARGE HAIL WILL BE ACROSS THIS
REGION...HOWEVER STRONGER CINH MAY LIMIT CONVECTIVE COVERAGE.  LOW
LEVEL VERTICAL SHEAR AND HODOGRAPH SIZE WILL BE MAXIMIZED INVOF
FRONT WHERE SFC WINDS SHOULD BE WEAK AND BACKED
DIRECTIONALLY...COMPARED TO WARM SECTOR.  0-3 KM SRH 200-500 J/KG
ARE POSSIBLE ALONG AND WITHIN 50-100 NM N OF FRONT...WHERE EFFECTIVE
LIFTED PARCELS STILL ARE ROOTED AT SFC IN FCST SOUNDINGS VALID LATE
AFTERNOON/EVENING.  THEREAFTER...ACTIVITY SHOULD BE MORE ELEVATED
BUT ALSO GREATER IN COVERAGE...WITH LARGE HAIL AND OCCASIONAL
DAMAGING GUSTS POSSIBLE.

...SRN APPALACHIANS TO COASTAL CAROLINAS...
TWO ROUNDS OF SEVERE POTENTIAL POSSIBLE OVER THIS REGION...MORNING
THEN AFTERNOON.  SHORT PERIOD OF FAVORABLE SFC HEATING IS POSSIBLE
AFTER 12Z...AHEAD OF CONVECTIVE COMPLEX NOW TAKING SHAPE OVER
KY...NERN TN AMD FAR SWRN VA.  GUSTS/HAIL NEAR SVR LEVELS ARE
POSSIBLE WITH THIS ACTIVITY BEFORE IT MOVES OFFSHORE...LEAVING
BEHIND REINFORCED/DISPLACED FRONTAL ZONE ACROSS PORTIONS SRN NC AND
SC...WNWWD ACROSS NRN GA.  THIS BOUNDARY AND ASSOCIATED INSTABILITY
GRADIENT SHOULD SERVE AS PRIMARY FOCUS FOR SUBSEQUENT CONVECTIVE
DEVELOPMENT/MOTION.  AIR MASS RECOVERY IS EXPECTED ALONG BOUNDARY
THROUGH LATE MORNING INTO LATE AFTERNOON...WITH ADDITIONAL
DEVELOPMENT POSSIBLE AS SFC DIABATICALLY WARMS.  WELL-MIXED BOUNDARY
LAYERS ARE EXPECTED WITH DEW POINT DEPRESSIONS AROUND 30 DEG
F...LEADING TO INVERTED-V THERMODYNAMIC PROFILES BELOW LCL AND
SUPPORTING MAINTENANCE TO SFC OF ANY HAIL OR STRONG-SEVERE GUSTS
GENERATED ALOFT.  DEEP-LAYER VERTICAL SHEAR PROFILES WILL SUPPORT
BOTH SUPERCELLULAR AND BOW MODES FOR CONVECTION.

...MT...
SCATTERED TSTMS ARE EXPECTED TO DEVELOP OVER HIGHER TERRAIN OF WRN
MT DURING DAY...MOVING EWD ACROSS HIGH PLAINS AND POSSIBLY
CONGEALING INTO ORGANIZED LINE/CLUSTER OF TSTMS.  DAMAGING WIND
SHOULD BE MAIN THREAT WITH OCCASIONAL HAIL ALSO PSBL...AS ACTIVITY
MOVES INTO DEEPLY HEATED/MIXED AIR MASS WITH STEEP LOW-MIDLEVEL
LAPSE RATES ALONG AND W OF SFC FRONT.  APCHG SHORTWAVE TROUGH SHOULD
ENHANCE CONVECTIVE ENVIRONMENT THROUGH COMBINATION OF INCREASING
LARGE SCALE ASCENT/COOLING ALOFT AND LEE-SIDE
ISALLOBARIC/ISALLOHYPSIC FORCING IN LOW LEVELS ACROSS MT.  LATTER
WILL HELP TO MAINTAIN BACKED/ENHANCED SFC WINDS INVOF BAROCLINIC
ZONE...AS WELL AS LOW LEVEL WAA AFTER DARK THAT MAY COMBINE WITH
FRONTAL LIFT TO SUSTAIN SOME CONVECTION INTO EVENING OR EARLY
OVERNIGHT HOURS AS FAR E AS WRN DAKOTAS/NERN WY.

...WI...
CONDITIONAL SVR RISK EXISTS OVER THIS REGION...WITH ONLY MINOR
ADJUSTMENTS IN INFLOW-LAYER DEW POINTS NEEDED TO SHIFT CONVECTIVE
POTENTIAL FROM BAND OF WEAK SHOWERS TO SEVERE SQUALL LINE.  STRONG
DEEP-LAYER FORCING AND WEAK CINH SHOULD COUNTERACT WEAK MOISTURE
ENOUGH TO RESULT IN POTENTIAL FOR FAST MOVING CONVECTION THIS
AFTERNOON...WITH THREAT FOR HAIL AND DAMAGING GUSTS.  AS SHORTWAVE
TROUGH DIGS SEWD TOWARD LS...VERY STRONG LARGE SCALE DPVA/ASCENT
WILL BE CONCENTRATED JUST TO ITS SE.  MUCH OF THIS REGIME WILL OCCUR
BENEATH LEFT EXIT REGION OF STRENGTHENING AND CYCLONICALLY
CURVED...115-130 KT JET MAX AT 250 MB...AND ALSO...INVOF VIGOROUS
LOW LEVEL FRONTOGENETIC FORCING.  ALTHOUGH BOUNDARY LAYER MOISTURE
WILL BE MRGL WITH SFC DEW POINTS 40S TO LOW 50S F...SFC HEATING
COMBINED WITH COOLING ALOFT SHOULD CONTRIBUTE TO DEEP ENOUGH
BUOYANCY PROFILE FOR DEEP CONVECTION.  SVR THREAT WILL DIMINISH EWD
THIS EVENING ACROSS LM AND LOWER MI WHERE LOW LEVEL AIR MASS SHOULD
BE MORE STABLE.

..EDWARDS/GRAMS.. 05/20/2006