WATCHES: Tornado Watch Number 257

WWUS20 KWNS 302259
SEL7
SPC WW 302259
ARZ000-OKZ000-TXZ000-010700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 257
NWS STORM PREDICTION CENTER NORMAN OK
555 PM CDT SAT APR 30 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

SOUTHWEST ARKANSAS
SOUTHEAST OKLAHOMA
NORTHEAST TEXAS

EFFECTIVE THIS SATURDAY AFTERNOON AND SUNDAY MORNING FROM 555 PM
UNTIL 200 AM 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 70 STATUTE
MILES EAST AND WEST OF A LINE FROM 10 MILES SOUTHWEST OF TYLER
TEXAS TO 25 MILES NORTH NORTHWEST OF DE QUEEN ARKANSAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU7).

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...INCIPIENT STORM DEVELOPMENT IS UNDERWAY ALONG COLD
FRONT OVER THE DALLAS-FT. WORTH AREA WITHIN A STRONGLY UNSTABLE AIR
MASS WITH MLCAPE VALUES OF 3000 J/KG. KINEMATIC ENVIRONMENT INVOF
COLD FRONT IS CHARACTERIZED BY A WEAK LOW-LEVEL WIND FIELD BUT 40-50
KT EFFECTIVE BULK SHEAR. HOWEVER...AS STORMS MATURE...THEY WILL
ENCOUNTER STRONGER LOW-LEVEL SHEAR AND HIGHER BOUNDARY LAYER
MOISTURE CONTENT WITH EWD EXTENT. AS SUCH...INITIAL HAZARDS WILL BE
LARGE HAIL AND LOCALLY DAMAGING WINDS WITH AN INCREASED TORNADO
THREAT AFTER 01/00Z.

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 24030.

...MEAD

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.