NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
.DAY ONE...TONIGHT.
WEATHER HAZARDS EXPECTED:
HEAT INDICES OVER 100 DEGREES.
THUNDERSTORMS...SOME OF MAY PRODUCE:
DAMAGING WINDS IN EXCESS OF 60 MPH.
QUARTER SIZED HAIL.
VERY HEAVY RAINFALL LEADING TO LOCALIZED FLASH FLOODING.
AREAS AFFECTED AND TIMING:
HEAT INDICES AT OR ABOVE 105 DEGREES ARE LIKELY INTO EARLY THIS
EVENING...ESPECIALLY SOUTH OF INTERSTATE 80.
ISOLATED TO SCATTERED THUNDERSTORMS MAY DEVELOP ACROSS PORTIONS
OF NORTHERN ILLINOIS BY LATE AFTERNOON. ADDITIONAL
THUNDERSTORMS DEVELOPING OVER PORTIONS OF IOWA AND SOUTHEAST
MINNESOTA MAY MOVE EAST INTO NORTHERN ILLINOIS AND NORTHWEST
INDIANA DURING THE LATE EVENING AND OVERNIGHT HOURS.
DISCUSSION:
A NEARLY STATIONARY FRONTAL BOUNDARY...REINFORCED BY COOLER
OUTFLOW FROM OVERNIGHT AND EARLY MORNING STORMS...STRETCHES
FROM NEAR THE QUAD CITIES TO NEAR KANKAKEE TO NORTH OF
RENSSELAER INDIANA LATE THIS AFTERNOON. VERY WARM...HUMID AND
UNSTABLE AIR RESIDES ALONG AND SOUTH OF THIS FRONT. ISOLATED TO
SCATTERED THUNDERSTORMS MAY DEVELOP ALONG THIS FRONT DURING THE
LATE AFTERNOON HOURS...AND MAY PERSIST INTO THE EVENING. STRONG
INSTABILITY AND THEIR POSITION ALONG THE SOUTHERN PERIPHERY OF
FASTER MID LEVEL FLOW ALOFT SUGGEST THESE STORMS MAY PRESENT A
THREAT OF ISOLATED SEVERE WEATHER...WITH DAMAGING WINDS AND
LOCALLY HEAVY RAINFALL THE PRIMARY THREATS.
THUNDERSTORMS WERE ALSO DEVELOPING ACROSS PORTIONS OF IOWA INTO
SOUTHEAST MINNESOTA AND WESTERN WISCONSIN THIS AFTERNOON...IN
ASSOCIATION WITH A MID LEVEL DISTURBANCE MOVING ACROSS THE AREA
WEST OF THE MISSISSIPPI RIVER. THIS DISTURBANCE WILL TRACK EAST
ACROSS WISCONSIN AND NORTHERN ILLINOIS LATER TONIGHT...AND WILL
LIKELY RESULT IN AN INCREASE IN THUNDERSTORM COVERAGE LATER
THIS EVENING AND OVERNIGHT. THESE STORMS WILL ALSO PRESENT THE
POTENTIAL FOR DAMAGING WINDS AND SOME HAIL...BUT WILL ALSO
LIKELY BE HEAVY RAINFALL PRODUCERS. PORTIONS OF THE NORTHERN
ILLINOIS PORTION OF THE OUTLOOK AREA HAVE RECEIVED SEVERAL
BOUTS OF HEAVY RAIN OVER THE PAST SEVERAL DAYS...AND ADDITIONAL
HEAVY RAINFALL COULD CAUSE NEW OR ADDITIONAL FLASH FLOODING.
.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.
THUNDERSTORMS WILL AGAIN BE POSSIBLE FRIDAY...AND POSSIBLY WILL
LINGER INTO FRIDAY EVENING ACROSS PORTIONS OF THE OUTLOOK AREA
SOUTH OF INTERSTATE 80.
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS AGAIN LATE SUNDAY...AND
PERIODS OF THUNDERSTORMS ARE POSSIBLE AGAIN TUESDAY INTO THURSDAY
OF NEXT WEEK.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING AND OVERNIGHT.
&&
COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO
