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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 54

NWS STORM PREDICTION CENTER NORMAN OK

210 AM CST FRI MAR 2 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME SOUTHWEST ILLINOIS

       MUCH OF CENTRAL MISSOURI



EFFECTIVE THIS FRIDAY MORNING FROM 210 AM UNTIL 700 AM CST.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 50 MILES NORTH OF

JOPLIN MISSOURI TO 20 MILES SOUTH OF ALTON ILLINOIS.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU4).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



DISCUSSION...ELEVATED CONVECTION IS DEVELOPING NEAR THE SE KS/SW MO

BORDER IN A ZONE OF STRONG LOW-LEVEL WAA...WHERE LOW-LEVEL MOISTURE

IS INCREASING RAPIDLY JUST ABOVE THE SURFACE.  EXPECT THIS ZONE OF

ASCENT/DESTABILIZATION TO SHIFT ENEWD OVER CENTRAL MO THROUGH THE

EARLY MORNING HOURS...WHICH WILL SUPPORT AN INCREASE IN BOTH

COVERAGE/INTENSITY OF THE CONVECTION.  THE COMBINATION OF MUCAPE AOA

1500 J/KG AND EFFECTIVE BULK SHEAR NEAR 50 KT WILL SUPPORT ELEVATED

SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL...AND POSSIBLY ISOLATED

DAMAGING GUSTS AS THE CONVECTION MATURES.  THE INITIAL SEVERE THREAT

WILL BE IN SW/W CENTRAL MO...AND WILL SPREAD AS FAR E AS THE SAINT

LOUIS AREA NEAR OR JUST BEFORE SUNRISE.



AVIATION...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 25040.





...THOMPSON

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