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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 356

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM CDT TUE MAY 24 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL OKLAHOMA

       NORTHWEST AND NORTH-CENTRAL TEXAS



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

1000 PM CDT.



...THIS IS A PARTICULARLY DANGEROUS SITUATION...



DESTRUCTIVE TORNADOES...LARGE HAIL TO 3 INCHES IN DIAMETER...

THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE

POSSIBLE IN THESE AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES WEST NORTHWEST OF

PONCA CITY OKLAHOMA TO 25 MILES SOUTH SOUTHWEST OF FORT WORTH

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

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 352...WW 354...WW 355...



DISCUSSION...TSTM INITIATION IS ANTICIPATED WITHIN THE NEXT HOUR OR

TWO ALONG THE DRYLINE FROM WRN OK INTO W-CNTRL TX.  STRONG HEIGHT

FALLS/DYNAMIC FORCING FOR ASCENT ASSOCIATED WITH NEGATIVELY TILTED

MIDLEVEL TROUGH EMERGING INTO THE PLAINS SHOULD SUPPORT A RAPID

INCREASE IN STORM COVERAGE THROUGH THE AFTERNOON.  WARM SECTOR AIR

MASS IS CHARACTERIZED BY A VERY MOIST BOUNDARY LAYER WITH DEWPOINTS

IN THE UPPER 60S TO LOWER 70S.  WHEN COUPLED WITH STEEP MIDLEVEL

LAPSE RATES...ENVIRONMENT IS MODERATELY TO STRONGLY UNSTABLE WITH

MLCAPE VALUES OF 2500-4000 J/KG.  DEEP-LAYER SHEAR STRENGTHENING TO

40-50 KT WILL PROMOTE RAPID SUPERCELL DEVELOPMENT WITH THE INITIAL

HAZARD BEING VERY LARGE HAIL.  INITIAL VEER-BACK WIND PROFILE

OBSERVED IN CURRENT VADS/PROFILERS IS EXPECTED TO TRANSITION TO

LARGE CLOCKWISE CURVED HODOGRAPHS BY 00Z WHERE 0-1 KM SRH WILL

APPROACH 400-500 M2/S2.  AS SUCH...EXPECT A RAPID INCREASE IN THE

THREAT FOR TORNADOES THIS AFTERNOON INTO EVENING...SOME OF WHICH

COULD BE LONG-TRACKED AND STRONG TO VIOLENT.



AVIATION...TORNADOES AND 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 23035.





...MEAD

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