[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 131748
SWODY2
SPC AC 131746

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1246 PM CDT THU JUL 13 2006

VALID 141200Z - 151200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MID/LOWER OH VALLEY
AND VICINITY...

...SYNOPSIS...
LARGE UPPER HIGH WILL PREVAIL ACROSS THE WRN CONUS...WHILE A
SHORT-WAVE TROUGH WILL MOVE EWD ACROSS THE MID AND UPPER MS/OH
VALLEYS AND GREAT LAKES AND SWD ACROSS THE PLAINS ON ERN PERIPHERY
OF THE RIDGE.  MEANWHILE...SMALLER-SCALE DISTURBANCES SHOULD MOVE
SEWD ACROSS THE NORTHEAST WITHIN NWLY FLOW REGIME.

MAIN SURFACE FEATURE WILL BE A COMBINATION SURFACE FRONT/CONVECTIVE
OUTFLOW BOUNDARY AHEAD OF SHORT-WAVE TROUGH CROSSING THE CENTRAL
CONUS. THOUGH EXACT LOCATION OF THIS BOUNDARY WILL DEPEND UPON
LOCATION AND INTENSITY OF ONGOING STORMS...THIS FEATURE SHOULD MOVE
EWD ACROSS THE MIDWEST...SEWD ACROSS THE MID MS VALLEY...AND SWD
ACROSS THE SRN PLAINS THROUGH THE PERIOD.

...MID AND LOWER OH/MID MS VALLEY REGIONS...
UPPER SHORT-WAVE TROUGH IS FORECAST TO MOVE EWD ACROSS THE MS/OH
VALLEYS AND GREAT LAKES REGION THIS PERIOD...AFFECTING AREAS AS FAR
S AS THE TN VALLEY.  THOUGH ASSOCIATED COLD FRONT SHOULD BE
WEAK...POTENTIAL FOR A STRONGER SURFACE BOUNDARY EXISTS DEPENDING
UPON THE EVOLUTION OF CONVECTION AND ASSOCIATED OUTFLOW LATE IN THE
DAY 1 PERIOD.

IN ANY CASE...MOIST AIRMASS WILL BE IN PLACE ACROSS THE
REGION...WITH MODELS INDICATING A BELT OF ENHANCED/ROUGHLY
UNIDIRECTIONAL LOWER TO MID-LEVEL FLOW /AROUND 30 KT/ ACROSS THE
LOWER OH VALLEY REGION.  SCENARIO IS COMPLICATED GIVEN CONVECTION
WHICH SHOULD BE ONGOING...BUT ATTM IT APPEARS THAT SUFFICIENT
INSTABILITY WILL DEVELOP AHEAD OF FRONT/CONVECTIVE OUTFLOW SOMEWHERE
WITHIN A ZONE FROM INDIANA/WRN OH INTO CENTRAL AND WRN KY AND
PERHAPS SRN IL/SERN MO/NRN TN. THIS COMBINED WITH MODERATE WLY FLOW
SUGGESTS AN ENHANCED POTENTIAL FOR DAMAGING WINDS...AND THUS WILL
INTRODUCE A SLIGHT RISK ACROSS THIS REGION.

FURTHER N INTO THE UPPER GREAT LAKES...NW ACROSS IL/IA...AND SW INTO
SRN MO/NRN AR...SCENARIO REMAINS MORE COMPLEX DUE TO LIKELIHOOD FOR
ONGOING CONVECTION.  WILL INCLUDE A LARGE 5% SEVERE THREAT AREA THIS
FORECAST TO ACCOUNT FOR SEVERE POTENTIAL...WITH ANY POSSIBILITY FOR
GREATER SEVERE THREAT IN THESE AREAS LARGELY DEPENDENT UPON
EVOLUTION OF DAY 1 CONVECTION. 

...SRN PLAINS WWD INTO ERN NM...
STRONG HEATING IS FORECAST S OF OUTFLOW-REINFORCED SURFACE BOUNDARY
WHICH SHOULD BE MOVING ACROSS OK/THE TX PANHANDLE DURING THE
DAY...AS UPPER VORT MAX MOVES SWD/SWWD AROUND ERN PERIPHERY OF UPPER
HIGH.  SUFFICIENT MOISTURE/INSTABILITY ALONG THE SURFACE FRONT
SHOULD ALLOW ONGOING THUNDERSTORMS EARLY IN THE PERIOD TO PERSIST --
AND THEN INCREASE DURING THE AFTERNOON COINCIDENT WITH DIURNAL
HEATING.  THOUGH FLOW ALOFT WILL BE RELATIVELY WEAK...SLY FLOW AT
LOW LEVELS BENEATH UPPER NLYS MAY PROVIDE SUFFICIENT SHEAR FOR SOME
STORM ORGANIZATION.  THIS COMBINED WITH HOT/DEEP MIXED LAYER
SUGGESTS A POTENTIAL FOR ISOLATED DAMAGING GUSTS.  WILL THEREFORE
INTRODUCE 5% SEVERE PROBABILITY ACROSS THIS AREA...WITH SOME
POTENTIAL FOR A SLIGHT RISK UPGRADE IN LATER FORECASTS.

...NRN NEW ENGLAND...
MODERATE NWLY FLOW ALOFT IS FORECAST ACROSS NEW ENGLAND ON BACK SIDE
OF MAIN UPPER TROUGH OFFSHORE. TIMING OF SMALLER-SCALE DISTURBANCES
MOVING SEWD ACROSS NEW ENGLAND REMAINS DIFFICULT...BUT MODELS HINT
THAT ONE FEATURE MAY CROSS THE REGION EARLY IN THE DAY...AND A
SECOND FEATURE MAY APPROACH LATE IN THE AFTERNOON.  DESPITE
QUESTIONS REGARDING TIMING...POTENTIAL FOR SUFFICIENT
DESTABILIZATION AND MODERATE FLOW ALOFT SUPPORT MAINTAINING 5%
SEVERE PROBABILITY ACROSS THIS REGION.

...N CENTRAL MT...
VERY SUBTLE UPPER DISTURBANCES ARE FORECAST TO MOVE EWD ACROSS SERN
BRITISH COLUMBIA/SRN ALBERTA/SRN SASKATCHEWAN DURING THE
DAY...WITHIN FAST BELT OF WEAKLY ANTICYCLONIC FLOW AROUND NRN
PERIPHERY OF WRN U.S. RIDGE.  LOW-LEVEL BAROCLINIC ZONE IS FORECAST
TO LIE ACROSS ID/MT...THOUGH DESTABILIZATION ALONG THIS FRONT IS
FORECAST TO BE MINIMAL AT BEST.  COULD A FEW ISOLATED STORMS
INITIATE OVER THE HIGHER TERRAIN OF MT...STRENGTH OF FLOW ALOFT
WOULD SUPPORT A THREAT FOR DAMAGING WINDS.  HOWEVER...GIVEN MEAGER
INSTABILITY AND POTENTIAL THAT ANY STORMS WILL REMAIN N OF THE
CANADA/U.S. BORDER...WILL MAINTAIN ONLY A SMALL CONDITION 5% SEVERE
THREAT ACROSS THIS REGION.

..GOSS.. 07/13/2006