

981 

WWUS20 KWNS 222046

SEL0

SPC WW 222046

ARZ000-OKZ000-230300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 180

NWS STORM PREDICTION CENTER NORMAN OK

350 PM CDT FRI APR 22 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       NORTHWEST ARKANSAS

       EASTERN OKLAHOMA



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 350 PM UNTIL

1000 PM CDT.



TORNADOES...HAIL TO 4 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 75 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTH OF ARDMORE

OKLAHOMA TO 40 MILES NORTH NORTHWEST OF FAYETTEVILLE ARKANSAS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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 178...WW 179...



DISCUSSION...THUNDERSTORMS ARE EXPECTED TO RAPIDLY FORM ALONG COLD

FRONT ADVANCING SOUTHEASTWARD INTO EASTERN OK THIS EVENING.  OTHER

MORE ISOLATED STORMS ARE POSSIBLE SOUTHWARD ALONG THE DRYLINE NEAR

THE RED RIVER.  VERY UNSTABLE CONDITIONS /MLCAPE OVER 3500 J/KG/

ALONG WITH SUFFICIENT VERTICAL SHEAR WILL POSE A THREAT OF

SUPERCELLS CAPABLE OF VERY LARGE HAIL AND DAMAGING WINDS.  LOW LEVEL

VERTICAL SHEAR IS NOT PARTICULARLY STRONG...BUT SUFFICIENT GIVEN THE

DEGREE OF INSTABILITY TO WARRANT A THREAT OF ISOLATED TORNADOES.



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

SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE

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

550. MEAN STORM MOTION VECTOR 27030.





...HART

