

005 

WWUS20 KWNS 102135

SEL7

SPC WW 102135

ARZ000-OKZ000-110300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 697

NWS STORM PREDICTION CENTER NORMAN OK

435 PM CDT MON AUG 10 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST ARKANSAS

       NORTH-CENTRAL AND NORTHEAST OKLAHOMA



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 435 PM UNTIL

1000 PM CDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

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 25 MILES SOUTH

SOUTHWEST OF PONCA CITY OKLAHOMA TO 30 MILES EAST OF FAYETTEVILLE

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.



OTHER WATCH INFORMATION...CONTINUE...WW 694...WW 695...WW 696...



DISCUSSION...VERY UNSTABLE AIRMASS AHEAD OF SURFACE OUTFLOW

BOUNDARY/COLD FRONT PUSHING INTO NRN OK LATE TODAY IS ALREADY

FUELING SEVERE THUNDERSTORM DEVELOPMENT OVER THE REGION.  STEEP LOW

LEVEL LAPSE RATES AND LARGE DOWNDRAFT-CAPE SHOULD ENHANCE CONVECTIVE

DOWNBURSTS...WITH 20-30 KT WLY EFFECTIVE SHEAR SUPPORTING SOME

ORGANIZATION INTO LINES OR SLOW MOVING CLUSTERS.  WIND DAMAGE WILL

BE PRIMARY THREAT...ALTHOUGH ISOLATED LARGE HAIL AND HEAVY RAINFALL

WILL BE ADDITIONAL HAZARDS THROUGH MUCH OF THE EVENING.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 28015.





...EVANS

