Severe Thunderstorm Watch 296

SEL6

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 296
NWS STORM PREDICTION CENTER NORMAN OK
515 PM CDT WED MAY 13 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WEST CENTRAL...CENTRAL...AND NORTHERN OKLAHOMA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 515 PM UNTIL
1100 PM CDT.

HAIL TO 3 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 EAST AND WEST OF A LINE FROM 20 MILES NORTHWEST OF
BARTLESVILLE OKLAHOMA TO 35 MILES SOUTHEAST OF CLINTON OKLAHOMA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU6).

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 293...WW 294...WW 295...

DISCUSSION...RAPID THUNDERSTORM DEVELOPMENT IS EXPECTED BY 23Z ALONG
THE COLD FRONT MOVING SEWD INTO N/NW OK. VERY STRONG INSTABILITY
/MLCAPE OF 3000-4000 J/KG/ AND WEAKENING CONVECTIVE INHIBITION WILL
SUPPORT STORM FORMATION/INTENSIFICATION...AND GRADUAL EVOLUTION INTO
A LINE OF STORMS ON THE FRONT. THE INITIAL THREAT WILL BE VERY
LARGE HAIL WITH THE MORE DISCRETE STORMS GIVEN 8.5-9 C/KM MID LEVEL
LAPSE RATES AND EFFECTIVE BULK SHEAR NEAR 30 KT...WITH DAMAGING
WINDS AND LARGE HAIL BECOMING COMMON THREATS LATER THIS EVENING AS
STORM COVERAGE INCREASES.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM
MOTION VECTOR 29025.

THOMPSON