SWODY1
SPC AC 151255
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0655 AM CST SUN NOV 15 2009
VALID 151300Z - 161200Z
...NO SVR TSTM AREAS FORECAST...
...SRN PLAINS THIS AFTERNOON INTO TONIGHT...
THE DEVELOPING CLOSED LOW OVER SW CO/NW NM THIS MORNING WILL MOVE
EWD TO KS/OK/TX TONIGHT. A SURFACE BAROCLINIC ZONE JUST SE OF I-44
IN MO/OK AS OF 12Z WILL LIKEWISE MOVE EWD/SEWD INTO WRN AR AND
CENTRAL/NE TX BY THE END OF THE PERIOD...IN RESPONSE TO PRESSURE
RISES ACROSS THE HIGH PLAINS IN THE IMMEDIATE WAKE OF THE MID LEVEL
LOW. THE FRONT IS PRECEDED BY A MODIFYING AIR MASS WITH BOUNDARY
LAYER DEWPOINTS RANGING FROM NEAR 60 F ALONG THE RED RIVER TO NEAR
70 F ACROSS THE EXTREME NW GULF.
TO THIS POINT...RELATIVELY WARM TEMPERATURE PROFILES ALOFT /TYPICAL
OF FALL/ HAVE LIMITED WARM SECTOR INSTABILITY DESPITE THE
INCREASINGLY MOIST BOUNDARY LAYER. HOWEVER...INSTABILITY WILL
INCREASE SOME DURING THE DAY ACROSS TX IN RESPONSE TO CONTINUED
MOISTENING... SURFACE HEATING...AND GRADUAL COOLING ALOFT WITH THE
APPROACHING MID LEVEL TROUGH. THE NET RESULT WILL BE MUCAPE OF
500-1000 J/KG OVER CENTRAL/NE TX THIS AFTERNOON INTO TONIGHT.
MEANWHILE...DEEP LAYER VERTICAL SHEAR WILL INCREASE GRADUALLY
THROUGH THIS EVENING OVER TX IN CONJUNCTION WITH THE EWD PROGRESSION
OF A LEAD SHORTWAVE TROUGH AND A BELT OF ENHANCED MID-UPPER FLOW NOW
FROM NRN MEXICO TO NW TX.
THE ONGOING ELEVATED CONVECTION OVER NRN OK/SE KS/SW MO WILL PERSIST
AND SPREAD SLOWLY EWD THROUGH ABOUT MIDDAY/EARLY AFTERNOON. BY
MID-LATE AFTERNOON...SURFACE-BASED THUNDERSTORM DEVELOPMENT IS
EXPECTED ALONG THE FRONT IN ERN OK. CONVECTION WILL THEN DEVELOP
SSWWD INTO NE AND CENTRAL TX TONIGHT...AS THE ENTIRE CONVECTIVE BAND
ALSO MOVES EWD. THERE WILL BE A WINDOW OF OPPORTUNITY FOR ISOLATED
STORMS WITH DAMAGING WINDS LATE THIS AFTERNOON INTO EARLY TONIGHT
WHERE THE MODEST INSTABILITY COINCIDES WITH 0-6 KM BULK SHEAR AOA 60
KT. A LACK OF CYCLOGENESIS WILL CONTRIBUTE TO WEAK LOW-LEVEL
FLOW/SHEAR IN THE WARM SECTOR...AND AT BEST A SMALL TORNADO THREAT
WITH EMBEDDED STORMS. LINGERING WARM TEMPERATURES ALOFT/POOR LAPSE
RATES WILL LIMIT ANY THREAT FOR LARGE HAIL.
..THOMPSON/HURLBUT.. 11/15/2009
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