NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
.DAY ONE...THIS AFTERNOON AND TONIGHT.
WEATHER HAZARDS EXPECTED:
THUNDERSTORMS...THE STRONGEST STORMS MAY PRODUCE:
GUSTY WINDS TO 50 MPH.
BRIEF DOWNPOURS.
FREQUENT LIGHTNING.
AREAS AFFECTED AND TIMING:
SCATTERED THUNDERSTORMS MAY DEVELOP ACROSS THE ENTIRE FORECAST
AREA DURING THE MID TO LATE AFTERNOON HOURS AND CONTINUE INTO
EARLY THIS EVENING.
DISCUSSION:
DECAYING THUNDERSTORM COMPLEX OVER SOUTHERN ILLINOIS...AND
A MID LEVEL...THUNDERSTORM INDUCED CIRCULATION EXITING THE AREA
TOWARD SOUTHWEST LOWER MICHIGAN HAVE ACTED TO GREATLY STABILIZE
THE AIR OVER NORTH AND CENTRAL ILLINOIS AND NORTHWEST INDIANA.
CONVECTIVE DEBRIS ACROSS THE REGION WILL CONTINUE TO DISSIPATE
QUICKLY HEADING INTO EARLY THIS AFTERNOON AND INCREASED SUNSHINE
WILL ALLOW FOR MODEST DESTABILIZATION TO THE POINT THAT THERE WILL
BE A THREAT OF RENEWED THUNDERSTORM DEVELOPMENT DURING THE MID TO
LATE AFTERNOON HOURS.
HOWEVER...THE REGION SOUTH AND WEST OF THE OUTLOOK AREA IS
EXPECTED TO BECOME MUCH MORE UNSTABLE...WITH MID LEVEL LAPSE RATES
RATHER STEEP OVER SOUTHWEST MISSOURI AND OVER WESTERN IOWA. LOW
LEVEL FORCING HAS BEEN DISRUPTED BY LAST NIGHTS CONVECTION...AND
PROFILER WINDS SUGGEST BETTER MOISTURE CONVERGENCE WILL BE
FOCUSED ALONG BOUNDARY FROM NORTHEAST OF KANSAS CITY AREA...INTO
THE LOWER OHIO VALLEY. IN ADDITION...STRONGER MID LEVEL DYNAMIC
FORCING FOR ORGANIZED STORMS WILL LIFT NORTHEAST ACROSS THE UPPER
MISSISSIPPI VALLEY THIS AFTERNOON IN ASSOCIATION WITH A VIGOROUS
SHORT WAVE MOVING ACROSS THE UPPER GREAT LAKES REGION.
IN SUMMARY...THOUGH THE OUTLOOK AREA IS NOT OUT OF THE WOODS IN
TERMS OF SEVERE THUNDERSTORM DEVELOPMENT...CONDITIONS APPEAR
UNFAVORABLE FOR ORGANIZED...WIDESPREAD SEVERE STORMS.
PORTIONS OF THE UPPER ILLINOIS RIVER WILL REMAIN NEAR BANK FULL.
PERIOD OF HEAVY RAIN TODAY COULD LEAD TO RENEWED RISES ON AREA
STREAMS AND RIVERS.
.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.
PORTIONS OF THE UPPER ILLINOIS RIVER WILL REMAIN NEAR BANK-FULL
THROUGH SUNDAY EVENING.
HIGH TEMPERATURES ARE EXPECTED TO REACH WELL INTO THE 90S ON
FRIDAY...IN COMBINATION WITH DEW POINTS IN THE LOWER 70S. THIS
WILL PRODUCE HEAT INDEX VALUES BETWEEN 100 AND 105 FRIDAY
AFTERNOON.
THERE IS A CHANCE OF THUNDERSTORMS FRIDAY NIGHT AND SATURDAY.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT.
&&
COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO
