WATCHES: Severe Thunderstorm Watch Number 697

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

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