

000 

WWUS20 KWNS 171829

SEL7

SPC WW 171829

ILZ000-INZ000-KYZ000-MOZ000-180200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 527

NWS STORM PREDICTION CENTER NORMAN OK

125 PM CDT TUE JUL 17 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN ILLINOIS

       SOUTHWEST INDIANA

       WESTERN KENTUCKY

       SOUTHEAST MISSOURI



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 125 PM UNTIL

900 PM CDT.



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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST

SOUTHWEST OF FARMINGTON MISSOURI TO 15 MILES SOUTHEAST OF

OWENSBORO KENTUCKY.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...LONG-LIVED LINEAR MCS IS CONTINUING SWD ACROSS SRN

IL...AND IS EXPECTED TO INTENSIFY AS IT MOVES INTO AN INCREASINGLY

UNSTABLE AIR MASS WITH MLCAPE OF 2500-3500 J/KG.  STEEP LOW LEVEL

LAPSE RATES WILL ALSO PROMOTE DEVELOPMENT OF STRONG DOWNDRAFTS AS

THE CONVECTION SPREADS SWD.  DESPITE DIMINISHING WINDS ALOFT WITH

SWD EXTENT...FAVORABLE THERMODYNAMIC ENVIRONMENT SHOULD MAINTAIN

ORGANIZED CONVECTIVE SYSTEM THROUGH THE AFTERNOON HOURS.



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 550. MEAN STORM

MOTION VECTOR 29020.





...WEISS

