[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 121252
SWODY1
SPC AC 121250

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0650 AM CST TUE DEC 12 2006

VALID 121300Z - 131200Z

...NO SVR TSTM AREAS FORECAST...

...MS/OH VALLEY REGION...
WATER VAPOR IMAGERY AND PROFILER DATA SHOW A MID LEVEL SHORTWAVE
TROUGH OVER NE TX/SE OK THIS MORNING WHICH WILL ROTATE NEWD TO THE
OH VALLEY BY TONIGHT.  AN ASSOCIATED SURFACE TROUGH/WEAK COLD FRONT
WILL MOVE EWD FROM E TX AND WRN AR TO THE MS RIVER BY THIS
EVENING...AND CONTINUE EWD INTO THE TN/OH VALLEYS TONIGHT WHILE
BECOMING MORE DIFFUSE.  A NARROW CORRIDOR OF MOISTURE RETURN
/BOUNDARY LAYER DEWPOINTS OF 56-64 F/ IS PRESENT IN ADVANCE OF THE
SURFACE TROUGH AND SW OF THE LARGE RIDGE OVER THE ATLANTIC COAST. 
THIS MOISTURE WILL SPREAD NEWD TO THE LOWER OH VALLEY AND EWD ACROSS
MS/WRN TN DURING THE DAY...BUT THE WARM SECTOR WILL REMAIN NARROW. 
REGIONAL SOUNDINGS SUGGEST THAT THE STEEPER MID LEVEL LAPSE RATES
ARE CONFINED TO THE MID LEVEL THERMAL TROUGH...WHICH IS LARGELY W/NW
OF THE RICHER LOW-LEVEL MOISTURE.  THIS CONFIGURATION IS AND WILL
CONTINUE TO LIMIT THE DEGREE OF INSTABILITY ACROSS THE MS AND LOWER
OH VALLEYS TODAY.

THE MAJORITY OF THE CONVECTION TODAY WILL REMAIN IN A PRE-FRONTAL
BAND...FOCUSED BY LARGE SCALE ASCENT/LOW-LEVEL WAA TO THE E AND NE
OF THE SURFACE-BASED INSTABILITY.  ASCENT ALONG THE SURFACE
TROUGH/WEAK COLD FRONT SHOULD BE RELATIVELY SHALLOW/WEAK...AND
THUNDERSTORM DEVELOPMENT SHOULD BE ISOLATED AT BEST ALONG THE
SURFACE TROUGH LATER TODAY.  IF THUNDERSTORMS DEVELOP...MID LEVEL
LAPSE RATES NEAR 7.5 C/KM AND 500 MB TEMPERATURES COLDER THAN -20 C
COULD SUPPORT A FEW STORMS WITH MARGINALLY SEVERE HAIL DURING THE
AFTERNOON/EARLY EVENING FROM NE AR/WRN TN INTO SRN IL/SW INDIANA. 
FARTHER S ACROSS LA/MS IN THE MOIST SECTOR...THE SEVERE STORM THREAT
WILL BE LIMITED BY POOR MID LEVEL LAPSE RATES AND WEAKENING
LOW-LEVEL FLOW/SHEAR DURING THE DAY.

..THOMPSON.. 12/12/2006