2 flash flood, 1 thunderstorm wind, 1 hail, as filed by the National Weather Service.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Chicago, IL wrote its last area forecast discussion before the first event at May 18, 12:45 AM CST, 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 145 AM CDT TUE MAY 18 2004 .PRELIMINARY DISCUSSION FOR MORNING ZONES/GRIDS: AT 11P FRONT NR MKE-MKIL-MKC SAGGING S. LN TS IMMEDIATELY ALONG THE FRONT MOVG E WITH BACK EDGE OVER E IA. LINE IN RIGHT ENTRANCE REGION OF JET PASSING TO OUR N. VAPOR PIC WOUD SEEM TO INDICATE VORT LOBE OVER ABOUT C IA PUSHING THE TS LINE EAST. RELIATIVEY FAST FLOW OVER N U.S. AND MODELS HAVE VERY NOISY 500 PATTERN. LOOKS LIKE THE VORT EARLY THIS MORNING AND THEN ANOTHER LAKE TONIGHT FOR S COUNTIES. LOOKS LIKE AFTER TODAY RIDGE MOVES OVERHEAD AS FLOW DRIFTS BACK N TO BORDER. THEN ANOTHER SYSTEM MOVES THRU FLOW ON THURSDAY TO N OF AREA. MAIN THING IS GRADUALLY BUILDING OF 588 HEIGHT LN OVER S MIDWEST ON THURSDAY INDICATING BUILDING HEAT TO S. LOOKS LIKE POTENTIAL VERY STORMY RING OF FIRE PATTERN TO SETUP OVERHEAD ON N FRINGE OF THIS RIDGE THURSDAY AFTERNOON INTO FRIDAY NIGHT BEFORE GENERAL TROF FROM W MOVES IN OVER WEEKEND. MODELS INDICATE VERY UNSTABLE AIRMASS OVERHEAD BEGINING THURSDAY AFTERNOON. ALL MODELS LOOK LITTLE SLOW ON RH PATTERN AT 06Z SO WILL SPEED THINGS UP IN FORECAST. WILL TRND TOWARD FASTER ETA RATHER THAN THE GFS. FLOOD WATCH WILL BE CANCELLED AS LOOKS LIKE HEAVY TS TO BE OUT OF WATCH AREA BY 4 AM ZONE TIME. EXISTING FLOOD WARNINGS WILL STILL RUN TIL EXPIRATION AS THERE STIL WILL BE LEFT OVER WATER TO CONTEND WITH. TEMPERATURES WILL BE MAJOR CHALLANGE NEXT FEW DAYS AS FRONT MOVES BACK AND FORTH OVER AREA AND ALSO OUTFLOW BOUNDRIES TO MESS THINGS UP. AF && .AVIATION... FOR 18Z TAFS...MVFR TO VFR CONDITIONS WITH SOUTHWEST SFC FLOW ANTICIPATED TO CONTINUE THROUGH TODAY AND EVENING AHEAD OF AN APPROACHING COLD FRONT. THE FRONT SHOULD ENTER INTO THE REGION AFTER 06Z WITH THE SFC WINDS BECOMING NORTHERLY BEHIND THAT. PRECIP WISE...SCATTERED TSRA ARE POSSIBLE THIS AFTERNOON WITH WIDESPREAD CONVECTION DEVELOPING OVER THE TERMINALS AFTER 01Z TONIGHT AND PERSISTING TO NEAR DAWN. LEFT OUT TSRA FOR TODAY DUE TO SCATTERED NATURE...WILL UPDATE TAFS IF CONVECTIVE COVERAGE BECOMES BETTER DEFINED. MFR CONDITIONS ARE EXPECTED WITH TONIGHTS ACTIVITY. && .LOT...WATCHES/WARNINGS/ADVISORIES... IL...FLASH FLOOD WATCH TIL 4AM N. FLOOD WARNINGS TIL 515/530 NE IL. IN...FLASH FLOOD WATCH TIL 4AM IN N OF KANKAKEE RVR. LK MI...NONE.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO IL 500 PM CDT MON MAY 17 2004 ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011- 019-181100- BENTON-BOONE-COOK-DE KALB-DU PAGE-FORD-GRUNDY-IROQUOIS-JASPER- KANE-KANKAKEE-KENDALL-LA SALLE-LAKE-LAKE IN-LEE-LIVINGSTON- MCHENRY-NEWTON-OGLE-PORTER-WILL-WINNEBAGO- 500 PM CDT MON MAY 17 2004 THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA. .DAY ONE...TONIGHT THERE IS A FLOOD WATCH IN EFFECT FOR THAT PART OF THE OUTLOOK AREA NORTH AND WEST OF APPROXIMATELY A BLOOMINGTON TO MOROCCO TO WHEATFIELD LINE. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE AREA. ISOLATED THUNDERSTORMS WERE STARTING TO DEVELOP IN EASTERN IOWA AND NORTHWEST ILLINOIS EARLY THIS EVENING...AND WILL BECOME MORE NUMEROUS AS THEY MOVE NORTHEAST INTO NORTH CENTRAL AND FAR NORTHEAST ILLINOIS DURING THE EVENING. NUMEROUS THUNDERSTORMS ARE EXPECTED ACROSS THE AREA LATE EVENING AND OVERNIGHT. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS...WITH DAMAGING WINDS THE MAIN THREAT. THERE IS A THREAT OF HEAVY RAIN...WITH POSSIBLE FLASH FLOODING IN THE FLOOD WATCH AREA. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY MORE THUNDERSTORMS ARE LIKELY TUESDAY...WITH A SLIGHT CHANCE OF SEVERE THUNDERSTORMS PRODUCING LARGE HAIL AND DAMAGING WINDS SOUTH OF I-80. THERE IS THE POTENTIAL FOR FLOODING FROM ANY HEAVY RAINFALL FROM STORMS TONIGHT AND EARLY TUESDAY. THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY...WITH A SLIGHT CHANCE OF SEVERE THUNDERSTORMS ACROSS THE AREA. THERE ARE ADDITIONAL CHANCES OF THUNDERSTORMS THURSDAY THROUGH FRIDAY NIGHT...AND SUNDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE) LMZ740>746-766-181100- WINTHROP HARBOR TO WILMETTE HARBOR-WILMETTE HARBOR TO NORTHERLY ISLAND-NORTHERLY ISLAND TO CALUMET HARBOR-CALUMET HARBOR TO GARY- GARY TO BURNS HARBOR-BURNS HARBOR TO MICHIGAN CITY-MICHIGAN CITY TO NEW BUFFALO-LAKE MICHIGAN- 500 PM CDT MON MAY 18 2004 THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS AND INDIANA WATERS OF LAKE MICHIGAN. .DAY ONE...TONIGHT THERE WILL BE ISOLATED TO SCATTERED THUNDERSTORMS THIS EVENING...BECOMING NUMEROUS LATE EVENING AND OVERNIGHT. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS...WITH DAMAGING WINDS THE MAIN THREAT. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY MORE THUNDERSTORMS ARE LIKELY TUESDAY MORNING. THERE ARE ADDITIONAL CHANCES OF THUNDERSTORMS THURSDAY THROUGH SUNDAY. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WWW.CRH.NOAA.GOV/LOT (LOWER CASE)
The Chicago radar (KLOT), 85 km away, was scanning. The volume nearest the first event began at 03:08 UTC.
2 flash flood, 1 thunderstorm wind, 1 hail. Local standard time, as filed.
Route 45 was closed due to high water at the Route 137 bridge.
Large tree limbs were blown down.
Extensive street and low-land flooding occurred after 1.5 inches of rain fell in 45 minutes.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2004Every state in 2004This day in weather historyWarnings in Illinois, May 2004
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5397379, 5397380, 5397381, 5397543.