SWODY1
SPC AC 251607
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1107 AM CDT FRI SEP 25 2009
VALID 251630Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF SRN KS AND NWRN
OK...
...NWRN OK AND SRN KS...
RESIDENT UPPER LOW THIS MORNING LOCATED SWRN CORNER NE/CO
BORDER...WILL FINALLY RESPOND TO INCREASINGLY WESTERLIES ACROSS SRN
CANADA AND BEGIN THE EJECTION PROCESS TODAY. VORT LOBE THAT HAS
ROTATED AROUND LOW MOVING SWD THRU ERN CO WILL HEAD EWD ACROSS SRN
KS/NRN OK LATER THIS AFTERNOON/EVENING.
WEAK SURFACE LOW SWRN KS WITH TROUGH EXTENDING INTO TX PANHANDLE
WILL PROVIDE A FOCUS FOR SURFACE BASED CONVECTIVE INITIATION BY
MID/LATE AFTERNOON AS THIS FEATURE SHIFTS EWD ACROSS WRN KS INTO
NWRN OK. WITH STEEP LAPSE RATES ASSOCIATED WITH COLD CORE UPPER
CIRCULATION AND STRONG LOW LEVEL HEATING...COUPLED WITH 35-40KT OF
DEEP LAYER SHEAR...CONDITIONS WILL BE IN PLACE FOR A FEW SEVERE
THUNDERSTORMS. EARLIER FORECASTS KEPT SVR PROBS AT A MINIMUM DUE TO
EXPECTED LIMITED INSTABILITY...MLCAPE AOB 500 J/KG. HOWEVER WITH
OBSERVED LOW 50 DEWPOINTS AND PWAT OF ABOUT .70 IN...SBCAPE TO 1000
J/KG COULD DEVELOP IN AREAS OF FULL HEATING BY MID AFTERNOON FROM
SCENTRAL KS INTO NWRN/NCENTRAL OK. THUS HAVE INCREASED THE THREAT
OF LARGE HAIL AND AS A RESULT ADDED A LOW END SLIGHT RISK FOR THE
AREAS EXPECTED TO DESTABILIZE THE GREATEST AHEAD OF SURFACE TROUGH.
WHILE SHEAR IS SUFFICIENT FOR ROTATING UPDRAFTS...THE MARGINAL
AMOUNT OF INSTABILITY LIMITS ANY TORNADO THREAT TO A POSSIBLE
BRIEF/ISOLATED OCCURRENCE. SUNSET SHOULD LEAD TO A QUICK END OF ANY
SEVERE THREAT.
...PORTIONS OF TN VALLEY...
HAVE TRIMMED THE LOW SEVERE WIND PROBABILITIES TO REGION OF OBSERVED
GREATEST HEATING/INSTABILITY FROM MID TN TO NRN AL. FURTHER W
EXTENSIVE CLOUD COVER PRECLUDES ANY VIGOROUS UPDRAFT POTENTIAL. WITH
THE VERY MOIST AIR MASS...PWAT NEAR 2 INCHES...AND MLCAPES TO 2000
J/KG WHERE SURFACE TEMPS REACH MID 80S...A FEW STRONG DOWNDRAFTS ARE
LIKELY. WEAK SHEAR AND LAPSE RATES PRECLUDES ANY MORE THAN A LOW
SEVERE WIND PROB...I.E. SEE TEXT.
..HALES/GARNER.. 09/25/2009
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