Zone Forecast

...FLASH FLOOD WATCH IN EFFECT THROUGH SUNDAY EVENING...

.REST OF TONIGHT...CHANCE OF SHOWERS AND THUNDERSTORMS LATE IN
THE EVENING...THEN SHOWERS AND THUNDERSTORMS LIKELY AFTER
MIDNIGHT. SOME THUNDERSTORMS MAY PRODUCE HEAVY RAINFALL. LOWS IN
THE LOWER 70S. LIGHT AND VARIABLE WINDS. CHANCE OF PRECIPITATION
60 PERCENT.
.SUNDAY...PARTLY SUNNY WITH A 40 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE LOWER 90S. HIGHEST HEAT INDEX
READINGS 100 TO 105 IN THE AFTERNOON. LIGHT AND VARIABLE WINDS
EARLY IN THE MORNING BECOMING WEST AROUND 10 MPH IN THE LATE
MORNING AND AFTERNOON.
.SUNDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. NORTH WINDS
AROUND 10 MPH.
.MONDAY...SUNNY. HIGHS IN THE LOWER 80S. LIGHT AND VARIABLE
WINDS.
.MONDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. LIGHT AND
VARIABLE WINDS.
.TUESDAY...MOSTLY SUNNY. HIGHS IN THE MID 80S.
.TUESDAY NIGHT...PARTLY CLOUDY. LOWS AROUND 70.
.WEDNESDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.WEDNESDAY NIGHT...PARTLY CLOUDY WITH A 40 PERCENT CHANCE OF
SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S.
.THURSDAY...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.THURSDAY NIGHT AND FRIDAY...PARTLY CLOUDY WITH A 40 PERCENT
CHANCE OF SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S. HIGHS
IN THE MID 80S.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. LOWS IN THE UPPER 60S.
.SATURDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE MID 80S.

Zone Forecast

...FLASH FLOOD WATCH IN EFFECT THROUGH SUNDAY EVENING...

.REST OF TONIGHT...CHANCE OF SHOWERS AND THUNDERSTORMS LATE IN
THE EVENING...THEN SHOWERS AND THUNDERSTORMS LIKELY AFTER
MIDNIGHT. SOME THUNDERSTORMS MAY PRODUCE HEAVY RAINFALL. LOWS IN
THE LOWER 70S. LIGHT AND VARIABLE WINDS. CHANCE OF PRECIPITATION
60 PERCENT.
.SUNDAY...PARTLY SUNNY WITH A 40 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE LOWER 90S. HIGHEST HEAT INDEX
READINGS 100 TO 105 IN THE AFTERNOON. LIGHT AND VARIABLE WINDS
EARLY IN THE MORNING BECOMING WEST AROUND 10 MPH IN THE LATE
MORNING AND AFTERNOON.
.SUNDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. NORTH WINDS
AROUND 10 MPH.
.MONDAY...SUNNY. HIGHS IN THE LOWER 80S. LIGHT AND VARIABLE
WINDS.
.MONDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. LIGHT AND
VARIABLE WINDS.
.TUESDAY...MOSTLY SUNNY. HIGHS IN THE MID 80S.
.TUESDAY NIGHT...PARTLY CLOUDY. LOWS AROUND 70.
.WEDNESDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.WEDNESDAY NIGHT...PARTLY CLOUDY WITH A 40 PERCENT CHANCE OF
SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S.
.THURSDAY...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.THURSDAY NIGHT AND FRIDAY...PARTLY CLOUDY WITH A 40 PERCENT
CHANCE OF SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S. HIGHS
IN THE MID 80S.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. LOWS IN THE UPPER 60S.
.SATURDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE MID 80S.

Zone Forecast

...FLASH FLOOD WATCH IN EFFECT THROUGH SUNDAY EVENING...

.REST OF TONIGHT...MOSTLY CLOUDY. CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE EARLY MORNING...THEN SHOWERS AND
THUNDERSTORMS LIKELY DURING THE PREDAWN HOURS. SOME THUNDERSTORMS
MAY PRODUCE HEAVY RAINFALL DURING THE PREDAWN HOURS. LOWS IN THE
LOWER 70S. LIGHT AND VARIABLE WINDS. CHANCE OF PRECIPITATION 60
PERCENT.
.SUNDAY...PARTLY SUNNY WITH A 40 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE LOWER 90S. HIGHEST HEAT INDEX
READINGS 100 TO 105 IN THE AFTERNOON. LIGHT AND VARIABLE WINDS
EARLY IN THE MORNING BECOMING WEST AROUND 10 MPH IN THE LATE
MORNING AND AFTERNOON.
.SUNDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. NORTH WINDS
AROUND 10 MPH.
.MONDAY...SUNNY. HIGHS IN THE LOWER 80S. LIGHT AND VARIABLE
WINDS.
.MONDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. LIGHT AND
VARIABLE WINDS.
.TUESDAY...MOSTLY SUNNY. HIGHS IN THE MID 80S.
.TUESDAY NIGHT...PARTLY CLOUDY. LOWS AROUND 70.
.WEDNESDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.WEDNESDAY NIGHT...PARTLY CLOUDY WITH A 40 PERCENT CHANCE OF
SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S.
.THURSDAY...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.THURSDAY NIGHT AND FRIDAY...PARTLY CLOUDY WITH A 40 PERCENT
CHANCE OF SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S. HIGHS
IN THE MID 80S.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. LOWS IN THE UPPER 60S.
.SATURDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE MID 80S.

Zone Forecast

...FLASH FLOOD WATCH IN EFFECT THROUGH SUNDAY EVENING...

.REST OF TONIGHT...MOSTLY CLOUDY. CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE EARLY MORNING...THEN SHOWERS AND
THUNDERSTORMS LIKELY DURING THE PREDAWN HOURS. SOME THUNDERSTORMS
MAY PRODUCE HEAVY RAINFALL DURING THE PREDAWN HOURS. LOWS IN THE
LOWER 70S. LIGHT AND VARIABLE WINDS. CHANCE OF PRECIPITATION 60
PERCENT.
.SUNDAY...PARTLY SUNNY WITH A 40 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE LOWER 90S. HIGHEST HEAT INDEX
READINGS 100 TO 105 IN THE AFTERNOON. LIGHT AND VARIABLE WINDS
EARLY IN THE MORNING BECOMING WEST AROUND 10 MPH IN THE LATE
MORNING AND AFTERNOON.
.SUNDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. NORTH WINDS
AROUND 10 MPH.
.MONDAY...SUNNY. HIGHS IN THE LOWER 80S. LIGHT AND VARIABLE
WINDS.
.MONDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. LIGHT AND
VARIABLE WINDS.
.TUESDAY...MOSTLY SUNNY. HIGHS IN THE MID 80S.
.TUESDAY NIGHT...PARTLY CLOUDY. LOWS AROUND 70.
.WEDNESDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.WEDNESDAY NIGHT...PARTLY CLOUDY WITH A 40 PERCENT CHANCE OF
SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S.
.THURSDAY...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.THURSDAY NIGHT AND FRIDAY...PARTLY CLOUDY WITH A 40 PERCENT
CHANCE OF SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S. HIGHS
IN THE MID 80S.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. LOWS IN THE UPPER 60S.
.SATURDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE MID 80S.

Hazardous Weather Outlook

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.

.DAY ONE...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:

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS EVENING
ACROSS PORTIONS OF NORTHWESTERN INDIANA. ADDITIONAL SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO MOVE ACROSS PORTIONS
OF NORTHERN ILLINOIS FROM EASTERN IOWA THIS EVENING.

A SECOND AREA OF THUNDERSTORMS MAY DEVELOP LATER THIS EVENING
ACROSS NORTHERN IOWA. SHOULD THESE THUNDERSTORMS DEVELOP...THE
COMPLEX OF THUNDERSTORMS COULD TRACK ACROSS NORTHERN ILLINOIS
AND NORTHWESTERN INDIANA LATER TONIGHT. IT APPEARS THAT THE
BEST AREAS THAT MAY BE IMPACTED BY THESE THUNDERSTORMS WILL BE
SOME OF THE SAME AREAS ALREADY HIT BY HEAVY RAINFALL OVER THE
PAST FEW DAYS.

THE DANGEROUS HEAT AND HUMIDITY WILL CONTINUE...ESPECIALLY
SOUTH OF INTERSTATE 80.

DISCUSSION:

DUE TO THE HEAVY RAINFALL PRODUCED THIS MORNING ACROSS NORTHERN
ILLINOIS AND THE FACT THAT ADDITIONAL HEAVY RAINFALL IS
POSSIBLE LATER TONIGHT INTO SUNDAY ACROSS THE SAME
AREAS...THERE IS A HIGH THREAT FOR ADDITIONAL FLASH FLOODING.
MUCH IF NOT ALL OF ANY RAINFALL THAT FALLS ACROSS NORTHERN
ILLINOIS WILL BE CONVERTED TO RUNOFF DUE TO THE SATURATED
GROUND. THIS RUNOFF COULD EASILY OVERWHELM SMALL STREAMS AND
DRAINAGE BASINS.

ALSO DUE TO THE HEAVY RAINFALL OVER THE PAST 48 HOURS LOCATIONS
ON THE DES PLAINES RIVER HAVE RAPIDLY REACHED FLOOD STAGE AND
WILL CONTINUE TO RISE THROUGH THIS EVENING.

LOCATIONS ALONG AND SOUTH OF INTERSTATE 80 SHOULD SEE VERY WARM
TEMPERATURES TONIGHT...WITH LOWS ONLY DROPPING INTO THE MID TO
UPPER 70S.

.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

Zone Forecast

...FLASH FLOOD WATCH IN EFFECT THROUGH SUNDAY EVENING...

.TONIGHT...SHOWERS AND THUNDERSTORMS LIKELY. SOME THUNDERSTORMS
MAY PRODUCE HEAVY RAINFALL. LOWS IN THE LOWER 70S. SOUTH WINDS
AROUND 10 MPH EARLY IN THE EVENING BECOMING LIGHT AND VARIABLE IN
THE LATE EVENING AND OVERNIGHT. CHANCE OF PRECIPITATION
60 PERCENT.
.SUNDAY...PARTLY SUNNY WITH A 40 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE LOWER 90S. HIGHEST HEAT INDEX
READINGS 100 TO 105 IN THE AFTERNOON. LIGHT AND VARIABLE WINDS
EARLY IN THE MORNING BECOMING WEST AROUND 10 MPH IN THE LATE
MORNING AND AFTERNOON.
.SUNDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. NORTH WINDS
AROUND 10 MPH.
.MONDAY...SUNNY. HIGHS IN THE LOWER 80S. LIGHT AND VARIABLE
WINDS.
.MONDAY NIGHT...MOSTLY CLEAR. LOWS IN THE LOWER 60S. LIGHT AND
VARIABLE WINDS.
.TUESDAY...MOSTLY SUNNY. HIGHS IN THE MID 80S.
.TUESDAY NIGHT...PARTLY CLOUDY. LOWS AROUND 70.
.WEDNESDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.WEDNESDAY NIGHT...PARTLY CLOUDY WITH A 40 PERCENT CHANCE OF
SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S.
.THURSDAY...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE UPPER 80S.
.THURSDAY NIGHT AND FRIDAY...PARTLY CLOUDY WITH A 40 PERCENT
CHANCE OF SHOWERS AND THUNDERSTORMS. LOWS IN THE LOWER 70S. HIGHS
IN THE MID 80S.
.FRIDAY NIGHT...PARTLY CLOUDY WITH A 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS. LOWS IN THE UPPER 60S.
.SATURDAY...PARTLY CLOUDY WITH A 20 PERCENT CHANCE OF SHOWERS AND
THUNDERSTORMS. HIGHS IN THE MID 80S.

Hazardous Weather Outlook

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
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