

571 

WWUS20 KWNS 222036

SEL9

SPC WW 222036

ARZ000-OKZ000-TXZ000-230500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 869

NWS STORM PREDICTION CENTER NORMAN OK

340 PM CDT SAT OCT 22 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR SOUTHWEST ARKANSAS

       CENTRAL AND SOUTHEAST OKLAHOMA

       PARTS OF NORTH-CENTRAL AND NORTHEAST TEXAS



EFFECTIVE THIS SATURDAY AFTERNOON FROM 340 PM UNTIL MIDNIGHT 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 85

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

WICHITA FALLS TEXAS TO 65 MILES EAST NORTHEAST OF PARIS TEXAS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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...MID-LVL SHORTWAVE TROUGH MOVING INTO NWRN OK WILL

CONTINUE TO TRANSLATE ESE TOWARD THE ARKLATEX BY LATE THIS EVE.

LLVL MOISTURE...CHARACTERIZED BY UPR 50S TO LWR 60S DEW

POINTS...HAVE COMBINED WITH STRONG HEATING TO SUPPORT MLCAPES AROUND

1500 J/KG ACROSS CNTRL/SRN OK AND N TX.  EXPECT TSTMS TO INITIATE

INVOF SWRN/CNTRL OK 22-23Z NEAR A WRMFNT.  VERTICAL SHEAR WILL BE

MORE THAN SUFFICIENT TO SUPPORT SUPERCELLS WITH INITIAL ACTIVITY

WITH LARGE HAIL THE PRIMARY THREAT.  AS LARGE-SCALE ASCENT AND STORM

NUMBER INCREASE...EXPECT TRANSITION INTO A POSSIBLE

FORWARD-PROPAGATING MCS...TRACKING ESE INTO N TX AND POSSIBLY THE

ARKLATEX REGION BY 06-07Z.  DMGG WIND GUSTS WILL BE THE PRIMARY

THREAT LATER THIS EVE.



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 450. MEAN STORM

MOTION VECTOR 30030.





...RACY

