

000 

WWUS20 KWNS 212047

SEL7

SPC WW 212047

OKZ000-TXZ000-220500-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 157

NWS STORM PREDICTION CENTER NORMAN OK

345 PM CDT SAT APR 21 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       THE OKLAHOMA PANHANDLE

       WEST TEXAS AND THE TEXAS PANHANDLE



EFFECTIVE THIS SATURDAY AFTERNOON FROM 345 PM UNTIL MIDNIGHT CDT.



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



DESTRUCTIVE TORNADOES...LARGE HAIL TO 2.5 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 80 STATUTE

MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF GUYMON

OKLAHOMA TO 10 MILES SOUTHWEST OF BIG SPRING TEXAS.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU7).



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 154...WW 155...WW 156...



DISCUSSION...TSTMS/SUPERCELLS EXPECTED TO FORM IN THE NEXT HOUR OR

SO IN NW PART OF WW AS LEE TOUGH/DRY LINE ACCELERATES ENE FROM NM.

ADDITIONAL STORMS MAY FORM INVOF CAPROCK ESCARPMENT/EDGE OF STRATOCU

FIELD IN THE TX PANHANDLE.  VERY STRONG LOW TO MID LEVEL SHEAR

COUPLED WITH STEEP LOW TO MID LEVEL LAPSE RATES AND FAVORABLE-TIMED

ARRIVAL OF LARGE SCALE ASCENT EXPECTED TO SUPPORT A FEW LONG-LIVED

SUPERCELLS WITH TORNADOES/LARGE HAIL.  ACTIVITY LIKELY TO EVOLVE

INTO BROKEN SEGMENTS WITH A CONTINUING THREAT FOR TORNADOES LATER

THIS EVENING AS NM VORT ACCELERATES NEWD.



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

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 23040.





...CORFIDI

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