* WHAT...DANGEROUSLY HOT AND HUMID CONDITIONS WITH MULTIPLE DAYS OFHEAT INDEX VALUES OF 100 TO 110 EXPECTED, ALONG WITH NIGHTTIME LOWS NOT FALLING BELOW THE MID 70S.

* WHERE...PORTIONS OF NORTH CENTRAL AND NORTHWEST ILLINOIS AND EAST CENTRAL AND NORTHEAST IOWA.

* WHEN...FROM NOON MONDAY TO 9 PM CDT TUESDAY.

* IMPACTS...HEAT RELATED ILLNESSES INCREASE SIGNIFICANTLY DURING EXTREME HEAT AND HIGH HUMIDITY EVENTS.

* ADDITIONAL DETAILS...THERE IS INCREASING LIKELIHOOD THAT EXTREME HEAT WILL PERSIST THROUGH MIDWEEK AND MAY LAST INTO LATE WEEK. THUNDERSTORMS AND ASSOCIATED CLOUDS MAY INTERRUPT THE HEAT AT TIMES LATE IN THE WEEK.