

737 

WWUS20 KWNS 090300

SEL0

SPC WW 090300

TXZ000-091000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 70

NWS STORM PREDICTION CENTER NORMAN OK

900 PM CST THU MAR 8 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH TEXAS



EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 900 PM

UNTIL 400 AM CST.



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 EAST AND WEST OF A LINE FROM 20 MILES NORTHEAST OF

COTULLA TEXAS TO 130 MILES SOUTH SOUTHEAST OF COTULLA TEXAS.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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.



DISCUSSION...TSTMS /INCLUDING A SUPERCELL/ HAVE DEVELOPED AHEAD OF

COLD FRONT TONIGHT WITHIN A MOIST...UNSTABLE AIR MASS WITH MUCAPE

VALUES OF 1000-2000 J/KG.  CAP OBSERVED ON 00Z CRP/BRO SOUNDINGS IS

LIKELY BEING OFFSET TO SOME DEGREE BY THE STRENGTHENING SLY/SELY

LOW-LEVEL WINDS WHICH IS ENHANCING INFLOW INTO THE ONGOING STORMS.

GIVEN THE PRESENCE OF 50-60 KT DEEP-LAYER SHEAR...ENVIRONMENT WILL

REMAIN FAVORABLE FOR ORGANIZED STORM MODES WITH ATTENDANT THREATS

FOR DAMAGING WINDS AND LARGE HAIL.



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 28020.





...MEAD

