

801 

WWUS20 KWNS 191751

SEL8

SPC WW 191751

OKZ000-TXZ000-200100-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 308

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM CDT THU MAY 19 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN OKLAHOMA

       NORTHWESTERN TEXAS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

800 PM CDT.



TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE

MILES EAST AND WEST OF A LINE FROM 20 MILES NORTHEAST OF ALVA

OKLAHOMA TO 100 MILES SOUTH OF CHILDRESS TEXAS.  FOR A COMPLETE

DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE

(WOUS64 KWNS WOU8).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 307...



DISCUSSION...STORMS HAVE BEGUN TO DEVELOP NEAR THE DRYLINE AND

LIKELY WILL INCREASE IN COVERAGE THROUGH THE AFTERNOON IN UNCAPPED

AND WARMING AIR MASS.  THE ENVIRONMENT HAS BECOME STRONGLY UNSTABLE

WITH MLCAPES NEAR 3000 J/KG AND DEEP LAYER SHEAR IS SUFFICIENT FOR

SUPERCELLS.  THE GREATEST THREAT WILL BE LARGE HAIL...THOUGH THE

RISK FOR TORNADOES WILL INCREASE THROUGH THE AFTERNOON AS THE LOW

LEVEL WINDS NEAR AND EAST OF THE DRYLINE ARE EXPECTED TO BACK AND

INCREASE IN SPEED THROUGH THE AFTERNOON.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

550. MEAN STORM MOTION VECTOR 21020.





...IMY

