

000 

WWUS20 KWNS 140642

SEL9

SPC WW 140642

ARZ000-LAZ000-MSZ000-TXZ000-141300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 139

NWS STORM PREDICTION CENTER NORMAN OK

140 AM CDT SAT APR 14 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       EXTREME SOUTHEAST ARKANSAS

       CENTRAL AND NORTHEAST LOUISIANA

       EXTREME WEST CENTRAL MISSISSIPPI

       EXTREME SOUTHEAST TEXAS



EFFECTIVE THIS SATURDAY MORNING FROM 140 AM UNTIL 800 AM 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 NORTHEAST OF MONROE

LOUISIANA TO 50 MILES SOUTH OF FORT POLK LOUISIANA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU9).



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 136...SEVERE THUNDERSTORM WATCH NUMBER 137. WATCH

NUMBER 136 137 WILL NOT BE IN EFFECT AFTER 140 AM CDT.

CONTINUE...WW 138...



DISCUSSION...THUNDERSTORMS HAVE EVOLVED INTO A NE-SW ORIENTED LINE

FROM NRN LA INTO SE TX.  THIS BAND OF CONVECTION WILL PERSIST

THROUGH THE MORNING HOURS AND MOVE EWD IN CONJUNCTION WITH A SURFACE

WAVE ON THE FRONT ACROSS NRN LA/SE AR.  MID-UPPER 60S BOUNDARY LAYER

DEWPOINTS ACROSS LA WILL CONTRIBUTE TO NEAR SURFACE-BASED

INSTABILITY...AND SOME DESTABILIZATION IS EXPECTED NEAR THE MS RIVER

LATER THIS MORNING.  VERTICAL SHEAR WILL REMAIN SUFFICIENTLY STRONG

FOR EMBEDDED SUPERCELLS WITH AN ASSOCIATED RISK FOR A COUPLE OF

TORNADOES...AS WELL AS THE POTENTIAL FOR DAMAGING WINDS/HAIL WITH

BOWING STRUCTURES IN THE LINE.



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 24040.





...THOMPSON

