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000 

WWUS20 KWNS 011000

SEL2

SPC WW 011000

ARZ000-ILZ000-MOZ000-011800-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 42

NWS STORM PREDICTION CENTER NORMAN OK

400 AM CST THU MAR 1 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       NORTHERN ARKANSAS

       SOUTHWEST ILLINOIS

       SOUTHERN AND EAST CENTRAL MISSOURI



EFFECTIVE THIS THURSDAY MORNING FROM 400 AM UNTIL NOON CST.



TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE

MILES EAST AND WEST OF A LINE FROM 5 MILES NORTHWEST OF ALTON

ILLINOIS TO 50 MILES SOUTHEAST OF RUSSELLVILLE ARKANSAS.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 39...WW 40...WW 41...



DISCUSSION...LINE OF SUPERCELL THUNDERSTORMS OVER SOUTHWEST MO INTO

WESTERN AR IS FORECAST TO TRANSLATE EAST-NORTHEASTWARD THIS MORNING

ACROSS WATCH AREA.  EXTREMELY STRONG LOW LEVEL WINDS...COUPLED WITH

APPROACHING 90-100 KT MID LEVEL JET WILL RESULT IN A VERTICAL SHEAR

ENVIRONMENT CONDUCIVE TO LONG TRACK SUPERCELLS CAPABLE OF

TORNADOES...LARGE HAIL...DAMAGING WINDS.  AIR MASS OVER EASTERN

PARTS OF WATCH ARE NOT PARTICULARLY UNSTABLE AT THIS TIME.

HOWEVER...STRONG LOW LEVEL THERMAL/MOISTURE ADVECTION WILL HELP TO

RAPIDLY DESTABILIZE THIS AREA SHORTLY AFTER SUNRISE.



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

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 24040.





...HART

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