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073 

WWUS20 KWNS 040843

SEL7

SPC WW 040843

ARZ000-OKZ000-TXZ000-041600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 87

NWS STORM PREDICTION CENTER NORMAN OK

345 AM CDT MON APR 4 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL ARKANSAS

       FAR SOUTHEAST OKLAHOMA

       FAR NORTHEAST TEXAS



EFFECTIVE THIS MONDAY MORNING FROM 345 AM UNTIL 1100 AM 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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES SOUTH

SOUTHEAST OF TEXARKANA ARKANSAS TO 20 MILES NORTH NORTHEAST OF

FLIPPIN ARKANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...PRE-FRONTAL CLUSTER OF TSTMS DEVELOPING OVER SWRN AR

ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY THIS MORNING AS

SURFACE COLD FRONT AND LEADING EDGE OF HEIGHT FALLS ATTENDANT TO SRN

HIGH PLAINS VORTICITY MAXIMUM MOVE INTO THE REGION.  LATEST

DIAGNOSTIC DATA SUGGEST THAT STORMS ARE LIKELY ELEVATED ABOVE A

STRONG CAP AND ROOTED WITHIN A STEEP LAPSE RATE ENVIRONMENT WITH

MUCAPE VALUES OF 2000-3000 J/KG.  AS SUCH...LARGE HAIL WILL BE THE

PRIMARY HAZARD WITH THE MOST INTENSE STORMS.



THE THREAT FOR LOCALLY DAMAGING WIND GUSTS AND PERHAPS A TORNADO MAY

INCREASE TOWARD SUNRISE AS THE STORMS BECOME PROGRESSIVELY MORE

ROOTED IN THE MOISTENING/DESTABILIZING BOUNDARY LAYER OVER CNTRL AR.



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 25035.





...MEAD

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