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WWUS20 KWNS 192245

SEL6

SPC WW 192245

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 156

NWS STORM PREDICTION CENTER NORMAN OK

545 PM CDT TUE APR 19 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND NORTH CENTRAL TEXAS



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 545 PM UNTIL

1100 PM CDT.



HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH

NORTHEAST OF CORSICANA TEXAS TO 65 MILES SOUTHWEST OF TEMPLE

TEXAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



OTHER WATCH INFORMATION...CONTINUE...WW 154...WW 155...



DISCUSSION...THUNDERSTORMS WILL CONTINUE TO DEVELOP SWD ALONG THE

DRYLINE-COLD FRONT INTERSECTION...WITH THE STORMS FED BY STRONG

INSTABILITY AND STEEP MIDLEVEL LAPSE RATES.  THE COMBINATION OF

MLCAPE VALUES IN EXCESS OF 4000 J/KG AND EFFECTIVE BULK SHEAR NEAR

40 KT WILL SUPPORT SUPERCELLS CAPABLE OF PRODUCING ISOLATED VERY

LARGE HAIL...ALONG WITH DAMAGING WINDS. FARTHER S...MORE ISOLATED

STORM DEVELOPMENT WILL BE POSSIBLE ALONG THE STALLED DRYLINE IN THE

HILL COUNTRY...WHERE STRONG SURFACE HEATING HAS WEAKENED THE

CAP...BUT FORCING FOR ASCENT IS WEAK.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM

MOTION VECTOR 32020.





...THOMPSON

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