

808 

WWUS20 KWNS 022147

SEL3

SPC WW 022147

ILZ000-MOZ000-030500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 643

NWS STORM PREDICTION CENTER NORMAN OK

445 PM CDT THU SEP 2 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHERN ILLINOIS

       CENTRAL AND SOUTHERN MISSOURI



EFFECTIVE THIS THURSDAY AFTERNOON FROM 445 PM UNTIL MIDNIGHT CDT.



HAIL TO 1.5 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 70

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

OF MONETT MISSOURI TO 25 MILES SOUTH OF DANVILLE ILLINOIS.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU3).



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.



OTHER WATCH INFORMATION...CONTINUE...WW 642...



DISCUSSION...THUNDERSTORMS ARE SLOWLY INCREASING IN COVERAGE AND

INTENSITY ALONG/AHEAD OF A COLD FRONT MOVING SEWD INTO LOWER MO AND

MIDDLE MS VALLEYS.  PRE-FRONTAL AIR MASS IS WARM WITH SURFACE

TEMPERATURES IN THE MID/UPPER 80S...AND DEW POINTS IN THE LOW 70S

ARE CONTRIBUTING TO MLCAPE OF 1500-2500 J/KG.  WINDS ALOFT AND DEEP

LAYER SHEAR IS EXPECTED TO INCREASE /ESPECIALLY OVER CNTRL PART SOF

MO AND IL/ AS UPSTREAM UPPER TROUGH MOVES TOWARD THE MS VALLEY

TONIGHT.  DAMAGING WIND GUSTS AND HAIL WILL BE THE PRIMARY SEVERE

THREATS.



AVIATION...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 550. MEAN STORM

MOTION VECTOR 26025.





...WEISS

