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WWUS20 KWNS 122021

SEL3

SPC WW 122021

OKZ000-130300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 773

NWS STORM PREDICTION CENTER NORMAN OK

320 PM CDT FRI AUG 12 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL OKLAHOMA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 320 PM UNTIL

1000 PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 90

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF

PONCA CITY OKLAHOMA TO 20 MILES SOUTH SOUTHWEST OF ARDMORE

OKLAHOMA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 771...WW 772...



DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN BOTH COVERAGE AND

INTENSITY ACROSS MUCH OF CENTRAL OK THROUGH LATE AFTERNOON AND INTO

THIS EVENING. THE WATCH AREA IS CURRENTLY SURROUNDED ON THREE SIDES

BY DEVELOPING DEEP CONVECTION AND AIRMASS ACROSS CENTRAL OK

CONTINUES TO DESTABILIZE. PULSE TO MULTICELLULAR STORMS POSING

PRIMARILY A THREAT OF DAMAGING DOWNBURST WINDS WILL CONTINUE TO COME

UP ALONG/WITHIN CONFLUENCE ZONE COINCIDENT WITH HIGHER BOUNDARY

LAYER THETA-E FROM NWRN TX NWD TO OKC METRO AREA. THIS DEVELOPMENT

WILL OCCUR ATOP A VERY HOT BOUNDARY LAYER WHERE DCAPE WELL IN EXCESS

OF 1000 J/KG WILL RESULT IN LOCALLY DAMAGING DOWNBURSTS BENEATH THE

STRONGER CORES. TO THE EAST...OUTFLOW BOUNDARY FROM MORNING STORMS

OVER TULSA AREA WILL PROVIDE A FOCUS FOR NEW SURFACE-BASED

DEVELOPMENT INTO THE EVENING. POTENTIALLY MORE ENHANCED LOW LEVEL

SHEAR ALONG THE OUTFLOW COULD INDUCE SUPERCELL STRUCTURE IN THIS

CONVECTION WITH LARGE HAIL AND HIGH WINDS POSSIBLE. LASTLY...MCS

DEVELOPMENT IS ANTICIPATED ALONG OUTFLOW BOUNDARY INTERSECTION

ACROSS SRN KS. THIS COMPLEX...SIMULATED BY STORM SCALE MODELS...MAY

DEVELOP SEWD ACROSS NRN/NERN AND CNTRL OK THROUGH THE EVENING WITH

AN INCREASING CHANCE OF DAMAGING WIND AND HAIL IN THESE AREAS.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 80

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

MOTION VECTOR 27020.





...CARBIN

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