

071 

WWUS20 KWNS 261801

SEL0

SPC WW 261801

TXZ000-CWZ000-270000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 70

NWS STORM PREDICTION CENTER NORMAN OK

1255 PM CDT THU MAR 26 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTH CENTRAL AND SOUTHEAST TEXAS

       COASTAL WATERS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL

700 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 55

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

COTULLA TEXAS TO 5 MILES EAST SOUTHEAST OF GALVESTON 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.



OTHER WATCH INFORMATION...CONTINUE...WW 68...WW 69...



DISCUSSION...SEVERE STORMS JUST SOUTH OF SAT ARE EXPECTED TO

CONTINUE MOVING ESEWD...WHILE OTHER STORMS IN ADVANCE OF THIS

CONVECTION ARE SLOWLY INTENSIFYING.  ACTIVITY IS ALONG A LOW LEVEL

BOUNDARY WHERE STRONGER HEATING IS OCCURRING TO THE

SOUTH...ENHANCING FRONTOGENETIC FORCING.  ENVIRONMENT IS MODERATELY

UNSTABLE SOUTH OF THE BOUNDARY WITH MLCAPE TO 2000J/KG.  DEEP LAYER

SHEAR REMAINS STRONG WITH EFFECTIVE BULK SHEAR AOA 40

KT...INDICATING THREAT FOR SUPERCELLS CAPABLE OF PRODUCING VERY

LARGE HAIL AND A FEW DAMAGING WIND GUSTS.  ACTIVITY SHOULD CONTINUE

MOVING IN A GENERAL EASTWARD DIRECTION ALONG THE NRN EDGE OF A

STRONG UPPER LEVEL JET AXIS.  ALTHOUGH AN ISOLATED BRIEF TORNADO IS

POSSIBLE...WEAKER LOW LEVEL FLOW AND LIMITED LOW LEVEL SHEAR AND

HELICITY SHOULD LIMIT OVERALL TORNADO THREAT.



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 550. MEAN STORM

MOTION VECTOR 24030.





...WEISS

