

012 

WWUS20 KWNS 201930

SEL5

SPC WW 201930

TXZ000-CWZ000-210300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 185

NWS STORM PREDICTION CENTER NORMAN OK

230 PM CDT FRI APR 20 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DEEP SOUTH TEXAS

       COASTAL WATERS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 230 PM UNTIL

1000 PM CDT.



HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75

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



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65

STATUTE MILES EAST AND WEST OF A LINE FROM 15 MILES SOUTH OF

MCALLEN TEXAS TO 30 MILES NORTH NORTHWEST OF ALICE TEXAS.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU5).



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 184...



DISCUSSION...SVR TSTMS EXPECTED TO DEVELOP ALONG AND POSSIBLY AHEAD

OF SFC COLD FRONT IN ENVIRONMENT CHARACTERIZED BY 2000-3000 J/KG

MLCAPE AND 40-50 KT EFFECTIVE SHEAR MAGNITUDES. SUPERCELLS AND

COLD-POOL DRIVEN CLUSTERS EACH ARE POSSIBLE...OFFERING

LARGE/DAMAGING HAIL AND RISK FOR SVR GUSTS.  TORNADO CANNOT BE RULED

OUT...BUT WITH WEAK AMBIENT/EFFECTIVE SRH OVER AREA...RISK IS VERY

DEPENDENT ON STORM-SCALE PROCESSES.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 30025.





...EDWARDS

