

367 

WWUS20 KWNS 201605

SEL2

SPC WW 201605

ARZ000-LAZ000-OKZ000-TXZ000-202300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 312

NWS STORM PREDICTION CENTER NORMAN OK

1105 AM CDT FRI MAY 20 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN ARKANSAS

       NORTHWEST LOUISIANA

       EASTERN OKLAHOMA

       NORTHEAST TEXAS



EFFECTIVE THIS FRIDAY MORNING AND EVENING FROM 1105 AM UNTIL 600

PM CDT.



TORNADOES...HAIL TO 1.5 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 70 STATUTE

MILES EAST AND WEST OF A LINE FROM 50 MILES NORTH NORTHWEST OF

RUSSELLVILLE ARKANSAS TO 5 MILES SOUTHEAST OF LONGVIEW TEXAS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).



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.



DISCUSSION...TSTMS SHOULD CONTINUE TO INTENSIFY THIS AFTERNOON AS

THEY ENCOUNTER A VERY MOIST AND MODERATELY UNSTABLE AIR MASS WITH

MLCAPE VALUES INCREASING TO 1500-2500 J/KG.  WHILE MID AND

HIGH-LEVEL WIND FIELD WILL REMAIN MARGINAL FOR STORM

ORGANIZATION...THE PRESENCE OF A 40-50 KT SLY LLJ AND RESULTANT

EFFECTIVE SRH OF 250-400 M2/S2 WILL PROMOTE ENHANCED LOW-LEVEL STORM

ROTATION WITH A RISK FOR TORNADOES.



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

SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE

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

500. MEAN STORM MOTION VECTOR 22030.





...MEAD

