267 ACUS11 KWNS 222242 SWOMCD SPC MCD 222241 ILZ000-INZ000-230100- SPC MESOSCALE DISCUSSION 1433 FOR NCNTRL IL...WRN/NWRN IN CONCERNING...SEVERE THUNDERSTORM WATCH #521... MARGINALLY SEVERE STORMS CONTINUE IN PORTIONS OF WW#521. WATCH WILL CONTINUE TO REMAIN IN EFFECT ACROSS SRN AND ERN PORTIONS OF WW...ALTHOUGH THERE IS A POSSIBILITY WW WILL BE CANCELLED AHEAD OF PROPOSED EXPIRATION TIME AT 23/01Z. MODERATELY STRONG COLD FRONT CONTINUES TO AID IN TSTM DEVELOPMENT IN PARTS OF WW#521. MESOANALYSIS REVEALS COLD FRONTAL AXIS LIES FROM CNTRL LK MICHIGAN...THRU NERN AND NCNTRL IL...INTO NCNTRL MO. CHICAGO VAD PROFILE DEPICTS WINDS HAVE BACKED TO THE NW...WHILE NORTH WEBSTER VAD ALSO SHOWS RECENT BACKING TO NW INDICATIVE OF IMPINGEMENT OF LARGE-SCALE FRONTAL PUSH THRU BOTH NERN IL AND NRN IND. ISOLATED TO SCATTERED MARGINALLY SEVERE STORMS WILL CONTINUE ALONG/AHEAD OF FRONTAL BOUNDARY MAINLY FROM AROUND JACKSONVILLE...EWD TO DANVILLE...NEWD INTO MUCH OF NRN IND THE NEXT FEW HOURS. RATHER WEAK DEEP LAYER SHEAR AND SR HELICITY VALUES SUGGEST POOR STORM ORGANIZATION WITH SMALL HAIL/STRONG WINDS BEING THE PRIMARY SEVERE THREATS. ..NADEN.. 07/22/02 PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...