Wednesday, March 18, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 181647
SWODY2
SPC AC 181646

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1146 AM CDT WED MAR 18 2009

VALID 191200Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

AN UPPER-LEVEL TROUGH IS FORECAST TO AMPLIFY THURSDAY ACROSS THE
MID-MS VALLEY AS AN UPPER-LEVEL RIDGE BUILDS INTO THE ROCKIES. AT
THE SFC...A COLD FRONT WILL MOVE SWD ACROSS THE CAROLINAS...GULF
COAST STATES AND SRN PLAINS. ISOLATED THUNDERSTORMS WILL BE POSSIBLE
ALONG THE FRONT FROM NRN MS ENEWD ACROSS THE SRN APPALACHIANS INTO
CNTRL NC DUE TO LOW-LEVEL CONVERGENCE AS SFC TEMPS WARM THURSDAY
AFTERNOON. THIS ACTIVITY IS NOT EXPECTED TO BE SEVERE DUE TO LIMITED
LOW-LEVEL MOISTURE AND WEAK LARGE-SCALE ASCENT. THUNDERSTORMS WILL
ALSO BE POSSIBLE THURSDAY AFTERNOON IN SOUTH FLORIDA WHERE SFC
DEWPOINTS SHOULD BE IN THE LOWER 60S F. HOWEVER...A LACK OF
LARGE-SCALE ASCENT AND WEAK VERTICAL SHEAR SHOULD LIMIT THE SEVERE
POTENTIAL WITH THIS CONVECTION.

FURTHER WEST IN THE SRN PLAINS...FORECAST SOUNDINGS THURSDAY
AFTERNOON SUGGEST MLCAPE VALUES COULD APPROACH 1000 J/KG ALONG A
MOIST AXIS WHERE SFC DEWPOINTS MAY BE IN THE LOWER TO MID 50S F FROM
NCNTRL TX SWWD INTO THE WRN TX HILL COUNTRY. THIS ALONG WITH STEEP
MID-LEVEL LAPSE RATES COULD BE SUFFICIENT FOR ISOLATED LARGE HAIL.
HOWEVER...MODEL FORECASTS KEEP CONVECTION VERY ISOLATED WITH THE GFS
NOT CONVECTING AT ALL PROBABLY DUE TO INSUFFICIENT LARGE SCALE
ASCENT. EVEN THOUGH A SLIM CONDITIONAL PROBABILITY OF HAIL
EXISTS...THE CONVECTIVE POTENTIAL APPEARS TOO LOW TO WARRANT A 5
PERCENT HAIL CONTOUR ATTM.

..BROYLES.. 03/18/2009

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