

000 

WWUS20 KWNS 122041

SEL8

SPC WW 122041

ARZ000-OKZ000-130300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 688

NWS STORM PREDICTION CENTER NORMAN OK

340 PM CDT SAT JUL 12 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST ARKANSAS

       CENTRAL AND EASTERN OKLAHOMA



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 340 PM UNTIL

1000 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 50

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES SOUTHWEST

OF ENID OKLAHOMA TO 25 MILES EAST NORTHEAST OF FORT SMITH

ARKANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...SCATTERED THUNDERSTORMS HAVE BEGUN TO DEVELOP OVER WEST

CENTRAL OK IN REGION OF HIGH CAPE AND MODEST WESTERLY MID LEVEL

FLOW.  THUNDERSTORM COVERAGE IS EXPECTED TO INCREASE THROUGH THE

EVENING ALONG REMNANT OUTFLOW BOUNDARIES...INTO EASTERN OK AND

NORTHWEST AR.  HIGH LOW LEVEL THETAE VALUES...SOME DRY AIR

ALOFT...AND SUFFICIENT WESTERLY FLOW ALOFT WILL SUPPORT A RISK OF

DAMAGING DOWNBURST WINDS IN STRONGEST CELLS.



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 27025.





...HART

