

333 

WWUS20 KWNS 132214

SEL6

SPC WW 132214

OKZ000-140400-



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

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