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806 

WWUS20 KWNS 201902

SEL0

SPC WW 201902

ARZ000-OKZ000-TXZ000-210200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 170

NWS STORM PREDICTION CENTER NORMAN OK

200 PM CDT WED APR 20 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       ARKANSAS

       FAR SOUTHEAST OKLAHOMA

       FAR NORTHEAST TEXAS



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 200 PM UNTIL

900 PM 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 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES NORTH OF DE

QUEEN ARKANSAS TO 60 MILES EAST OF LITTLE ROCK ARKANSAS.  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 168...WW 169...



DISCUSSION...ELEVATED TSTMS ARE INCREASING IN COVERAGE THIS

AFTERNOON N OF SYNOPTIC COLD FRONT...LIKELY BEING DRIVEN BY A BAND

OF ENHANCED ASCENT TIED TO LOW-AMPLITUDE IMPULSE MOVING ACROSS THE

TX PNHDL AND OK.  GIVEN THE PRESENCE OF STEEP MIDLEVEL LAPSE

RATES...MUCAPE OF 1000-2000 J/KG AND 40-50+ KT OF EFFECTIVE BULK

SHEAR...SETUP WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF HAIL TO

THE SIZE OF GOLF BALLS.



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 27035.





...MEAD

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