

346 

WWUS20 KWNS 271254

SEL9

SPC WW 271254

TXZ000-271800-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 199

NWS STORM PREDICTION CENTER NORMAN OK

755 AM CDT MON APR 27 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF SOUTH TEXAS



EFFECTIVE THIS MONDAY MORNING AND AFTERNOON FROM 755 AM UNTIL 100

PM CDT.



HAIL TO 2 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 45

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

NORTHWEST OF DEL RIO TEXAS TO 5 MILES EAST NORTHEAST OF SAN

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

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 197...WW 198...



DISCUSSION...MCS CONTINUES TO INTENSIFY THIS MORNING WHILE

PROPAGATING SWD INTO A MOIST AND MODERATELY UNSTABLE AIR MASS

/MUCAPE OF 2500 J PER KG/ PER 12Z DRT SOUNDING.  THIS INSTABILITY IN

CONJUNCTION WITH 40-50 KT OF EFFECTIVE BULK SHEAR AND AN

ORGANIZED/MATURE COLD POOL SHOULD SUSTAIN SYSTEM WITH THE POTENTIAL

FOR EMBEDDED SUPERCELL AND/OR BOWING STRUCTURES.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 33030.





...MEAD/CORFIDI

