

369 

WWUS20 KWNS 192248

SEL6

SPC WW 192248

TXZ000-200500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 56

NWS STORM PREDICTION CENTER NORMAN OK

545 PM CDT TUE MAR 19 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF CENTRAL AND SOUTHEAST TEXAS



EFFECTIVE THIS TUESDAY AFTERNOON FROM 545 PM UNTIL MIDNIGHT 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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 125 MILES WEST

NORTHWEST OF AUSTIN TEXAS TO 30 MILES SOUTH SOUTHEAST OF COLLEGE

STATION 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.



DISCUSSION...THUNDERSTORM DEVELOPMENT IS UNDERWAY ACROSS CENTRAL TX

NEAR THE INTERSECTION OF A DIFFUSE TROUGH/DRYLINE AND WNW-ESE

ORIENTED SURFACE FRONT.  THE AIR MASS S OF THE FRONT IS MODERATELY

UNSTABLE WITH BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 50S AND

TEMPERATURES IN THE LOW-MID 80S...WHICH IS DRIVING MLCAPE AROUND

1500 J/KG.  MEANWHILE...WATER VAPOR IMAGERY SHOWS THE APPROACH OF A

MID-UPPER JET STREAK MOVING FROM NM INTO W CENTRAL TX...AND ASCENT

IN THE EXIT REGION OF THIS JET STREAK WILL OVERSPREAD CENTRAL TX

THIS EVENING.  THUS...THUNDERSTORMS ARE EXPECTED TO INCREASE IN

COVERAGE/INTENSITY THIS EVENING...IN AN ENVIRONMENT WITH SUFFICIENT

DEEP-LAYER VERTICAL SHEAR FOR SUPERCELLS.  LARGE HAIL WILL BE THE

PRIMARY SEVERE THREAT WITH THE INITIAL SUPERCELLS...AND THE RISK FOR

A FEW DAMAGING GUSTS WILL DEPEND MORE ON UPSCALE GROWTH INTO A

CLUSTER THROUGH STORM MERGERS.



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 30025.





...THOMPSON



977 

WWUS20 KWNS 192248

SEL6

SPC WW 192248

TXZ000-200500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 56

NWS STORM PREDICTION CENTER NORMAN OK

545 PM CDT TUE MAR 19 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF CENTRAL AND SOUTHEAST TEXAS



EFFECTIVE THIS TUESDAY AFTERNOON FROM 545 PM UNTIL MIDNIGHT 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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 125 MILES WEST

NORTHWEST OF AUSTIN TEXAS TO 30 MILES SOUTH SOUTHEAST OF COLLEGE

STATION 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.



DISCUSSION...THUNDERSTORM DEVELOPMENT IS UNDERWAY ACROSS CENTRAL TX

NEAR THE INTERSECTION OF A DIFFUSE TROUGH/DRYLINE AND WNW-ESE

ORIENTED SURFACE FRONT.  THE AIR MASS S OF THE FRONT IS MODERATELY

UNSTABLE WITH BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 50S AND

TEMPERATURES IN THE LOW-MID 80S...WHICH IS DRIVING MLCAPE AROUND

1500 J/KG.  MEANWHILE...WATER VAPOR IMAGERY SHOWS THE APPROACH OF A

MID-UPPER JET STREAK MOVING FROM NM INTO W CENTRAL TX...AND ASCENT

IN THE EXIT REGION OF THIS JET STREAK WILL OVERSPREAD CENTRAL TX

THIS EVENING.  THUS...THUNDERSTORMS ARE EXPECTED TO INCREASE IN

COVERAGE/INTENSITY THIS EVENING...IN AN ENVIRONMENT WITH SUFFICIENT

DEEP-LAYER VERTICAL SHEAR FOR SUPERCELLS.  LARGE HAIL WILL BE THE

PRIMARY SEVERE THREAT WITH THE INITIAL SUPERCELLS...AND THE RISK FOR

A FEW DAMAGING GUSTS WILL DEPEND MORE ON UPSCALE GROWTH INTO A

CLUSTER THROUGH STORM MERGERS.



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 30025.





...THOMPSON

