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WWUS20 KWNS 030439

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SPC WW 030439

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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 257

NWS STORM PREDICTION CENTER NORMAN OK

1140 PM CDT FRI MAY 2 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       PARTS OF SOUTHEAST ARKANSAS

       PARTS OF NORTHERN AND EASTERN LOUISIANA

       LARGE PART OF CENTRAL AND NORTHERN MISSISSIPPI



EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 1140 PM

UNTIL 700 AM CDT.



TORNADOES...HAIL TO 2 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 90 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES NORTHWEST OF COLUMBUS

MISSISSIPPI TO 20 MILES EAST OF ALEXANDRIA LOUISIANA.  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.



OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO

WATCH NUMBER 253...TORNADO WATCH NUMBER 254...TORNADO WATCH

NUMBER 255. WATCH NUMBER 253 254 255 WILL NOT BE IN EFFECT AFTER

1140 PM CDT.



DISCUSSION...SEVERE THUNDERSTORMS CONTINUE TO REDEVELOP AHEAD OF

SLOW MOVING FRONTAL ZONE ERN AR INTO ERN TX.  STRONG UPSTREAM TROUGH

AND DIVERGENT UPPER JET WILL ENHANCE BOTH MID LEVEL SHEAR AND LARGE

SCALE ASCENT REMAINDER OF NIGHT.  WITH A VERY MOIST AND MDTLY

UNSTABLE SLY FLOW CONTINUING ACROSS WATCH AREA...POTENTIAL FOR

TORNADIC SUPERCELLS WILL PERSIST AS THE TREND IS FOR SLOW

DEVELOPMENT EWD THRU THE NIGHT.



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

SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE

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

500. MEAN STORM MOTION VECTOR 24030.





...HALES

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