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WWUS20 KWNS 271735

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SPC WW 271735

ARZ000-LAZ000-TXZ000-280100-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 78

NWS STORM PREDICTION CENTER NORMAN OK

1235 PM CDT TUE MAR 27 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTHWEST AND SOUTH CENTRAL ARKANSAS

       NORTHWEST LOUISIANA

       EXTREME NORTHEAST TEXAS



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 1235 PM UNTIL

800 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 95 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTHWEST OF

SHREVEPORT LOUISIANA TO 50 MILES EAST NORTHEAST OF EL DORADO

ARKANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...A CLUSTER OF TSTMS HAS SHOWN EMBEDDED SUPERCELL

STRUCTURES ACROSS EXTREME NE TX DURING THE PAST HOUR...WHILE OTHER

STORMS ARE FORMING IN A SEPARATE CLUSTER IN SW AR.  THE SHV VWP

REVEALS A NARROW CORRIDOR WITH FAVORABLE VERTICAL SHEAR FOR

SUPERCELLS...AND IT APPEARS THERE IS SOME ORGANIZATION TO THE STORM

CLUSTERS ON THE MESOSCALE.  WITH GRADUAL DESTABILIZATION CONTINUING

ACROSS AR/NRN LA IN ADVANCE OF THE STORMS...THERE IS THE POTENTIAL

FOR THE ISOLATED TORNADO AND DAMAGING WIND/HAIL THREAT TO PERSIST

THROUGH THE AFTERNOON ACROSS NW LA INTO SW AR.  ADDITIONALLY...MORE

ISOLATED TSTMS WILL DEVELOP ACROSS E TX AND SPREAD NEWD INTO WRN LA

ALONG THE INSTABILITY AXIS.  THE PRIMARY THREAT WITH THESE STORMS

WILL BE ISOLATED LARGE HAIL AND DAMAGING GUSTS.



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 24025.





...THOMPSON

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