

040 

WWUS20 KWNS 231754

SEL1

SPC WW 231754

ILZ000-INZ000-240100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 341

NWS STORM PREDICTION CENTER NORMAN OK

1255 PM CDT MON MAY 23 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND EASTERN ILLINOIS

       CENTRAL INDIANA



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL

800 PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75

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



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTHEAST

OF INDIANAPOLIS INDIANA TO 35 MILES WEST SOUTHWEST OF DECATUR

ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 337...WW 338...WW

339...WW 340...



DISCUSSION...BOW ECHO NEAR STL IS EXPECTED TO CONTINUE ENEWD THIS

AFTERNOON AT 45-55 KT.  DOWNSTREAM AIR MASS ACROSS WW AREA IS

WARMING/DESTABILIZING WITH MLCAPE OF 1500-2000 J/KG.  WHEN COUPLED

WITH 35-40 KT OF DEEP WLY SHEAR...SETUP WILL FAVOR A CONTINUATION OF

MCS WITH ADDITIONAL SEVERE STORM DEVELOPMENT POSSIBLE ALONG COLD

FRONT MOVING INTO THE AREA FROM THE W/NW.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 26045.





...MEAD

