Friday, April 25, 2008

Mesoscale Discussion 739, Regarding Watch 235, Plans To Extend Watch Until Midnight

MESOSCALE DISCUSSION 0739
NWS STORM PREDICTION CENTER NORMAN OK
0939 PM CDT FRI APR 25 2008
AREAS AFFECTED...SCNTRL TX
CONCERNING...SEVERE THUNDERSTORM WATCH
235
...
VALID 260239Z - 260345Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 235
CONTINUES.
A THREAT FOR LARGE HAIL AND ISOLATED WIND DAMAGE WILL CONTINUE
ACROSS WW 235 OVER THE NEXT FEW HOURS. THE WATCH WILL BE LOCALLY
EXTENDED TO 05Z AND WILL INCLUDE THE SAN ANTONIO AREA.
LATEST SFC ANALYSIS SHOWS A COLD FRONT EXTENDING WSWWD ACROSS THE TX
HILL COUNTRY WITH NEAR 70 F DEWPOINTS LOCATED ACROSS MUCH OF SCNTRL
TX. THIS IS CREATING MODERATE TO STRONG INSTABILITY MAINLY SOUTHEAST
OF DEL RIO WITH OBJECTIVE ANALYSIS SHOWING MLCAPE VALUES IN THE 2000
TO 3000 J/KG RANGE. ALTHOUGH FORCING IS WEAK...LOW-LEVEL CONVERGENCE
IS ENHANCED ALONG AND JUST SOUTH OF THE FRONTAL BOUNDARY. THIS ALONG
WITH MODERATE VERTICAL SHEAR EVIDENT ON THE DEL RIO 00Z SOUNDING
SHOULD CONTINUE TO SUPPORT SCATTERED TO NUMEROUS SEVERE STORMS
THROUGH LATE EVENING. IN ADDITION...LAPSE RATES ARE VERY STEEP
/850-500 MB LAPSE RATES OF 8.0 C/KM/ ON THE DEL RIO SOUNDING
SUGGESTING A THREAT FOR LARGE HAIL AND ISOLATED WIND DAMAGE SHOULD
PERSIST UNTIL MIDNIGHT ACROSS SCNTRL TX.
..BROYLES.. 04/26/2008

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