NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
.DAY ONE...THIS AFTERNOON AND TONIGHT.
WEATHER HAZARDS EXPECTED:
THUNDERSTORMS...SOME MAY PRODUCE:
HEAVY RAINFALL WITH FLASH FLOODING.
FREQUENT LIGHTNING.
DAMAGING WINDS IN EXCESS OF 60 MPH.
OPPRESSIVE HEAT AND HUMIDITY.
AREAS AFFECTED AND TIMING:
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE TO MOVE
ACROSS NORTHERN ILLINOIS NORTH OF INTERSTATE 80 THROUGH EARLY
AFTERNOON. DURING THE AFTERNOON HOURS THERE IS CONSIDERABLE
UNCERTAINTY REGARDING ADDITIONAL THUNDERSTORM DEVELOPMENT. IT
DOES APPEAR THAT ADDITIONAL THUNDERSTORMS MAY DEVELOP ALONG AND
TO THE SOUTH OF THE CURRENT LINE OF THUNDERSTORMS MOVING ACROSS
NORTHERN ILLINOIS. IF THIS DOES OCCUR...THIS WOULD AFFECT AREAS
ALONG AND SOUTH OF INTERSTATE 80 LATER THIS
AFTERNOON...ESPECIALLY IN INDIANA.
THE DANGEROUS HEAT AND HUMIDITY WILL CONTINUE...ESPECIALLY
SOUTH OF INTERSTATE 80.
DISCUSSION:
STRONG THUNDERSTORMS PRODUCED VERY HEAVY RAINFALL OVERNIGHT
WITH AMOUNTS UP TO 7 INCHES ALREADY OBSERVED AT SOME LOCATIONS
OVER THE DES PLAINES RIVER BASIN. LOCATIONS ON THE DES PLAINES
RIVER HAVE RAPIDLY REACHED FLOOD STAGE AND WILL CONTINUE TO
RISE THIS AFTERNOON.
WITH ADDITIONAL PERIODS OF HEAVY RAINFALL POSSIBLE THROUGH
SUNDAY AFTERNOON...ADDITIONAL FLASH FLOODING AND SIGNIFICANT
RISES ON AREA RIVERS ARE POSSIBLE OVER THE NEXT 24 TO 36 HOURS.
THE MOST LIKELY LOCATION FOR FLASH FLOODING WILL BE ALONG AND
NORTH OF INTERSTATE 88. HOWEVER...THIS THREAT AREA MAY BEGIN TO
SHIFT SOUTH AROUND THE INTERSTATE 80 CORRIDOR LATER THIS
AFTERNOON.
WITH INCREASING SUNSHINE LATER TODAY...LOCATIONS SOUTH OF
INTERSTATE 80 SHOULD SEE TEMPERATURES RISE INTO THE MIDDLE 90S.
WITH HIGH HUMIDITY ALREADY IN PLACE...HEAT INDEX VALUES SHOULD
REACH 110 TO 115 DEGREES.
LOCATIONS ALONG THE INTERSTATE 80 CORRIDOR...AWAY FROM THE
CHICAGO METRO AREA...SHOULD SEE TEMPERATURES REACH INTO THE
UPPER 80S TO THE LOW 90S. HEAT INDEX VALUES SHOULD REACH
BETWEEN 100 AND 105 DEGREES. THE HEAT INDEX OVER THE CHICAGO
METRO AREA SHOULD BE BETWEEN 95 AND 100 DEGREES.
.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
LOCATIONS SOUTH OF INTERSTATE 80 WILL SEE HEAT INDEX VALUES OF
110 TO 115 DEGREES ON SUNDAY.
LOCATIONS ALONG THE INTERSTATE 80 CORRIDOR WILL SEE HEAT INDEX
VALUES OF AROUND 105 TO 110 DEGREES ON SUNDAY.
THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS SUNDAY AND AGAIN
WEDNESDAY THROUGH FRIDAY.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NECESSARY THROUGH TONIGHT...ESPECIALLY
FOR FLASH FLOODING.
&&
COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO
