SWODY2
SPC AC 251649
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1149 AM CDT FRI SEP 25 2009
VALID 261200Z - 271200Z
...NO SVR TSTM AREAS FORECAST...
...MID MS AND OH VALLEY REGION...
UPPER LOW THAT HAS MEANDERED ABOUT THE CNTRL PLAINS REGION FOR THE
LAST FEW DAYS WILL FINALLY BE KICKED EWD AS UPSTREAM HEIGHTS BEGIN
TO FALL IN RESPONSE TO STRONG SPEED MAX ALONG THE U.S./CANADIAN
BORDER. IN FACT LATEST MODEL GUIDANCE SUGGEST UPPER LOW WILL OPEN
UP ACROSS ERN KS/MO EARLY IN THE PERIOD THEN QUICKLY EJECT INTO ERN
OH/WRN PA BY THE END OF THE PERIOD. AS THIS OCCURS A POCKET OF
FAIRLY COLD MID LEVEL TEMPERATURES...H5 ON THE ORDER OF MINUS
16-18C...WILL OVERSPREAD MUCH OF MO/IL BY MID DAY...THEN INTO IND BY
MID AFTERNOON. ALTHOUGH MOISTURE IS SOMEWHAT LIMITED ACROSS THIS
REGION IT APPEARS FOCUSED ASCENT WITHIN THE EXIT REGION OF UPPER JET
SHOULD ENHANCE THE PROSPECT FOR ROBUST CONVECTION CAPABLE OF
GENERATING HAIL. A FEW STORMS COULD PRODUCE MARGINALLY SEVERE HAIL
WITHIN STEEPER LAPSE RATE ENVIRONMENT...PRIMARILY BETWEEN 18-00Z
TIME FRAME NORTH OF MID LEVEL JET CORE.
...MIDDLE ATLANTIC COAST...
AS CNTRL PLAINS UPPER LOW IS SHUNTED EAST INTO THE OH VALLEY...WEAK
HEIGHT FALLS WILL EXTEND SEWD INTO THE MIDDLE ATLANTIC REGION LATE.
SUBSEQUENT LARGE SCALE FORCING MAY INDUCE A WEAK SFC LOW/WAVE ALONG
WRN FRINGE OF RETREATING ANTICYCLONE. NAM IS A BIT MORE AGGRESSIVE
WITH SFC DEVELOPMENT NEAR THE NC COAST...THOUGH LOW LEVEL WARM
ADVECTION SHOULD EXTEND CONSIDERABLY FARTHER INLAND ACROSS VA INTO
PA. FORECAST LAPSE RATES ARE NOT EXPECTED TO BE THAT STEEP AND
UNLESS BOUNDARY LAYER CAN MOISTEN/DESTABILIZE SIGNIFICANTLY INLAND
IT WILL BE DIFFICULT TO GENERATE SUFFICIENT INSTABILITY TO WARRANT
ANY MEANINGFUL THREAT FOR SEVERE THUNDERSTORMS. FOR THIS REASON
HAVE REDUCED THE SEVERE PROBABILITIES INLAND BUT WILL KEEP 5%
PROBABILITY FOR SEVERE ALONG THE IMMEDIATE NC/VA COAST.
..DARROW.. 09/25/2009
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