

509 

WWUS20 KWNS 182052

SEL6

SPC WW 182052

OKZ000-190400-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 306

NWS STORM PREDICTION CENTER NORMAN OK

350 PM CDT WED MAY 18 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL OKLAHOMA



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 350 PM UNTIL

1100 PM CDT.



TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTHEAST OF FORT

SILL OKLAHOMA TO 15 MILES NORTH NORTHWEST OF ALVA OKLAHOMA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU6).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 305...



DISCUSSION...ISOLATED STORM DEVELOPMENT IS ANTICIPATED WITHIN THE

NEXT ONE TO TWO HOURS ALONG DRYLINE WHICH HAS BECOME STATIONARY OVER

WRN OK.  AIR MASS E OF DRYLINE IS CHARACTERIZED BY DEWPOINTS IN THE

LOW/MID 60S...WHICH WHEN COUPLED WITH MIDLEVEL LAPSE RATES OF AROUND

7 C/KM...IS RESULTING IN A MODERATELY UNSTABLE AND WEAKLY CAPPED

ENVIRONMENT WITH MLCAPE AROUND 2000 J/KG.  PROFILER DATA ACROSS ERN

NM SUGGEST THAT CIRRUS PLUME SPREADING EWD ACROSS WRN TX INTO WRN OK

IS ASSOCIATED WITH A 50 KT MIDLEVEL JET STREAK WHICH WILL SERVE TO

STRENGTHEN DEEP-LAYER SHEAR THROUGH THIS EVENING.  LOW-LEVEL SHEAR

SHOULD ALSO INCREASE AROUND OR SHORTLY AFTER 19/00Z WITH VERTICAL

WIND PROFILES BECOMING QUITE CONDUCIVE FOR SUPERCELL DEVELOPMENT.

VERY LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH TORNADOES WILL

BE POSSIBLE WITH ANY MATURE SUPERCELLS THAT CAN PERSIST INTO THIS

EVENING.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 24025.





...MEAD

