A large complex of thunderstorms developed over east central Illinois, south of Interstate 80, and moved southeast during the evening of July 20th. These thunderstorms produced winds over 60 mph in several locations which blew down trees, trees limbs and power lines.
Every event with a place to put it; 1 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 episode as NWS LOT wrote it up.
A large complex of thunderstorms developed over east central Illinois, south of Interstate 80, and moved southeast during the evening of July 20th. These thunderstorms produced winds over 60 mph in several locations which blew down trees, trees limbs and power lines. A few locations received torrential rainfall. Piper City measured 2.52 inches, Coal City measured 2.31 inches, and Bourbonnais measured 2.21 inches.
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 Jul 20, 1:43 PM CST, 4 hours 33 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 230 PM CDT WED JUL 202005 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... FINALLY SOME WELCOME RAIN WITH PASSING MCS MOVING THROUGH NRN IL/SRN WI. ISOLATED CELLS AHEAD OF THE MAIN LINE PASSING THROUGH NWRN IN AND THE MAIN LINE SHOULD HOLD TOGETHER LONG ENOUGH TO BRING A LITTLE MORE RAIN TO PORTIONS OF NERN IL AND NWRN IN. THIS LEADS IN TO THE IMMEDIATE PROBLEM OF MORE CNVTV ACTIVITY OVERNIGHT. STRONG MOIST, WARM ADVECTION AHEAD OF THE COLD FRONT HAS ALLOWED SIGNIFICANTLY HIGHER DEWPOINTS TO STREAM NORTHWARD...REACHING INTO THE LOW 70S. SO WITH MORE MOISTURE IN PLACE...AN INCREASING LOW-LEVEL JET...MODEST INSTABILITY AND ADEQUATE FORCING...ALL INGREDIENTS POINTING TOWARDS THE CHANCE FOR MORE RAIN OVERNIGHT. THE NAM DEVELOPS SERIOUS FEEDBACK PROBLEMS TONIGHT. THE GFS SEEMS TO BE THE BETTER WAY TO GO FOR THE SFC PATTERN...WITH A SECOND ROUND OF PCPN OVERNIGHT AND PUSHING INTO THE SOUTHERN COUNTIES. BY TOMORROW MORNING...HIGH PRESSURE BUILDING OVER THE NORTHERN GREAT LAKES WILL FORCE THE COLD FRONT SOUTH OF THE CWA...STALLING OUT OVER CENTRAL IL/IN. FOLLOWING THE GFS SFC PATTERN...A DEVELOPING LOW OVER THE NRN PLAINS SHOULD HELP THE FRONT RETURN A LITTLE TO THE NORTH...INCREASING THE CHANCES FOR PCPN OVER THE SOUTHERN PORTIONS OF THE CWA...GENERALLY SOUTH OF I-80 AND THE KANKAKEE RIVER. THE OTHER PROBLEM REMAINS THE HEAT SITUATION FOR SUNDAY AND MONDAY. WILL KEEP WITH THE TRENDS OF PREVIOUS SHIFTS. THE GUIDANCE IS CONSISTENT WITH BUILDING THE UPPER RIDGE OVER THE CENTRAL PLAINS AND SHIFTING OVER THE UPPER MIDWEST. TEMPERATURES SHOULD HAVE NO TROUBLE REACHING INTO THE MIDDLE TO UPPER 90S WITH DEWPOINTS REACHING INTO THE LOW 70S. THIS COMBINATION WOULD GIVE A HEAT INDEX OF 100-105 IN THE CHICAGO METRO AREA AND 105 TO 109 IN LOCATIONS SOUTH OF I-80. KREIN && .AVIATION DISCUSSION REGARDING 12Z TAFS: PERPLEXING QUESTION THIS MRNG IS HOW TO DEAL WITH LINEAR/BOW MCS THAT HAS EVOLVED OVR MN-NRN IA. 06Z ETA12 AND EXPERIMENTAL WRF MODELS BRING THIS INTO RFD AREA ARND 18Z THEN THRU CHI BY 20Z. CURRENT WATER VAPOR SATLT LOOPS SHOW DECENT AREA OF DOWNWARD MOMENTUM BHD THIS TSTM COMPLEX SUGGESTING IT WILL CONTINUE TO BOW ESEWD AS PROGGED. HOWEVER...IR IMAGERY PAST HR HAS SHOWN SOME WARMING IN ANVIL CANOPY...SUGGESTING A WEAKENING TREND...AND A CORRESPONDING DCRS IN LIGHTNING OUTPUT RATE HAS BEEN NOTED. SKIES VFR WITH ONLY A FEW PATCHES OF MID LVL CLOUDINESS AHD OF THIS SYS SO THERE WILL BE PLENTY OF DIURNAL HEATING OVR AREA WITH TEMPS RISING INTO LOWER-MID 90S. IN ADDN...SFC DEWPOINTS IN UPR 60S AND LWR 70S HAVE BEEN ADVECTING NWD AND ARE EXPECTED TO REACH NRN IL-NWRN IND BY ERLY AFTN. AMS FCST TO BECOME VERY UNSTABLE WITH CAPES ABV 4000 AND LIFTED INDEX ARND -8. THINKING IS THAT ALTHO LN IS WEAKENING ATTM...THERE/S ENUF FORCING AS IT WILL BE MOVING INTO UNSTABLE AMS ERLY-MID AFTN TO WARRANT TEMPO MENTION OF THUNDER WITH BRIEF IFR-MVFR CONDS AND WINDSHFT TO WNW. WILL BRING CHC THUNDER IN AGAIN DURG OVERNIGHT HRS AS INDICATIONS ARE THAT STRENGTHENING LLVL JET AND STG ISENTROPIC LIFT WILL PROMOTE NOCTURNAL TSTM DVLPMT. MERZLOCK && .WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 400 PM CDT WED JUL 20 2005 ILZ003>006-008-010>014-019>022-023-032-033-039-INZ001-002-010-011- 019-211100- WINNEBAGO-BOONE-MCHENRY-LAKE IL-OGLE-LEE-DE KALB-KANE-DU PAGE-COOK- LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-IROQUOIS-FORD- LAKE IN-PORTER-NEWTON-JASPER-BENTON- 400 PM CDT WED JUL 20 2005 THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA. .DAY ONE... TONIGHT THERE IS A CHANCE FOR SEVERE THUNDERSTORMS PRODUCING STRONG... DAMAGING WINDS OVER MUCH OF NORTHERN ILLINOIS AND NORTHWESTERN INDIANA THROUGH MIDNIGHT TONIGHT. THE MAIN THREAT OF SEVERE THUNDERSTORMS IS CONCENTRATED SOUTH OF I-90 AND ROUTE 20 IN ILLINOIS AND ALL OF NORTHWESTERN INDIANA. SPOTTER ACTIVATION MAY BE REQUIRED THROUGH MIDNIGHT TONIGHT. .DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY ON SUNDAY...HEAT INDICES WILL REACH 100 TO 105 ACROSS NORTHERN ILLINOIS NORTH OF I-80. HEAT INDICES WILL REACH 105 TO 110 SOUTH OF I-80...FROM THE KANKAKEE AND ILLINOIS RIVER VALLEYS SOUTHWARD. THESE LEVELS MAY POSE A HAZARD WITH PROLONGED EXPOSURE OR EXTENDED PHYSICAL ACTIVITY....ESPECIALLY TO THOSE WITH SENSITIVITY TO HEAT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED THROUGH MIDNIGHT TONIGHT. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO (LOWER CASE) LMZ740>745-766-211100- WINTHROP HARBOR IL TO MICHIGAN CITY IN- LAKE MICHIGAN- 400 PM CDT WED JUL 20 2005 THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS AND INDIANA WATERS OF LAKE MICHIGAN. .DAY ONE... TONIGHT THERE IS A CHANCE FOR SEVERE THUNDERSTORMS THROUGH MIDNIGHT TONIGHT. THESE STORMS HAVE THE POTENTIAL TO PRODUCE STRONG...DAMAGING WINDS OVER THE NEARSHORE WATERS OF LAKE MICHIGAN FROM NORTHERLY ISLAND ILLINOIS TO MICHIGAN CITY INDIANA. THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE WIND GUSTS TO 50 KNOTS. .DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO (LOWER CASE)
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 125 PM CDT WED JUL 20 2005 ILZ005-010>011-201930- DEKALB-LEE-MCHENRY- 125 PM CDT WED JUL 20 2005 ...THE NATIONAL WEATHER SERVICE HAS CANCELED SEVERE THUNDERSTORM WATCH 651 FOR THE FOLLOWING AREA... IN ILLINOIS THIS CANCELS 3 COUNTIES IN NORTH CENTRAL ILLINOIS DE KALB... LEE... IN NORTHEAST ILLINOIS MCHENRY... THIS INCLUDES THE CITIES OF...DEKALB...DIXON AND WOODSTOCK. ILZ006-012>014-019>023-032>033-039-INZ001>002-010>011- 019-202300- COOK-DUPAGE-FORD-GRUNDY-IROQUOIS-KANE-KANKAKEE-KENDALL-LAKE- LASALLE-LIVINGSTON-WILL-BENTON-JASPER-LAKE-NEWTON-PORTER- 125 PM CDT WED JUL 20 2005 ...SEVERE THUNDERSTORM WATCH NUMBER 651 REMAINS VALID UNTIL 6 PM CDT... IN ILLINOIS THIS WATCH INCLUDES 12 COUNTIES IN CENTRAL ILLINOIS LIVINGSTON... IN EAST CENTRAL ILLINOIS FORD... IROQUOIS... IN NORTH CENTRAL ILLINOIS LA SALLE... IN NORTHEAST ILLINOIS COOK... DUPAGE... GRUNDY... KANE... KANKAKEE... KENDALL... LAKE ILLINOIS... WILL... IN INDIANA THIS WATCH INCLUDES 5 COUNTIES IN NORTHWEST INDIANA BENTON... JASPER... LAKE INDIANA... NEWTON... PORTER... THIS INCLUDES THE CITIES OF...AURORA...CHICAGO...FOWLER...GARY... JOLIET...KANKAKEE...MOROCCO...MORRIS...OSWEGO...OTTAWA... PIPER CITY...PONTIAC...RENSSELAER...VALPARAISO... WATSEKA AND WAUKEGAN.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 204 PM CDT WED JUL 20 2005 ILZ006-012>013-019>021-202015- DUPAGE-GRUNDY-KANE-KENDALL-LAKE-LASALLE- 204 PM CDT WED JUL 20 2005 ...THE NATIONAL WEATHER SERVICE HAS CANCELED SEVERE THUNDERSTORM WATCH 651 FOR THE FOLLOWING AREA... IN ILLINOIS THIS CANCELS 6 COUNTIES IN NORTH CENTRAL ILLINOIS LA SALLE... IN NORTHEAST ILLINOIS DUPAGE... GRUNDY... KANE... KENDALL... LAKE... THIS INCLUDES THE CITIES OF...AURORA...MORRIS...OSWEGO... OTTAWA AND WAUKEGAN. ILZ014-022>023-032>033-039-INZ001>002-010>011-019-202300- COOK-FORD-IROQUOIS-KANKAKEE-LIVINGSTON-WILL-BENTON-JASPER-LAKE- NEWTON-PORTER- 204 PM CDT WED JUL 20 2005 ...SEVERE THUNDERSTORM WATCH NUMBER 651 REMAINS VALID UNTIL 6 PM CDT... IN ILLINOIS THIS WATCH INCLUDES 6 COUNTIES IN CENTRAL ILLINOIS LIVINGSTON... IN EAST CENTRAL ILLINOIS FORD... IROQUOIS... IN NORTHEAST ILLINOIS COOK... KANKAKEE... WILL... IN INDIANA THIS WATCH INCLUDES 5 COUNTIES IN NORTHWEST INDIANA BENTON... JASPER... LAKE INDIANA... NEWTON... PORTER... THIS INCLUDES THE CITIES OF...CHICAGO...FOWLER...GARY...JOLIET... KANKAKEE...MOROCCO...PIPER CITY...PONTIAC...RENSSELAER... VALPARAISO AND WATSEKA.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 309 PM CDT WED JUL 20 2005 ILZ014-022>023-032-INZ001>002-202115- COOK-KANKAKEE-LIVINGSTON-WILL-LAKE-PORTER- 309 PM CDT WED JUL 20 2005 ...THE NATIONAL WEATHER SERVICE HAS CANCELED SEVERE THUNDERSTORM WATCH 651 FOR THE FOLLOWING AREA... IN ILLINOIS THIS CANCELS 4 COUNTIES IN CENTRAL ILLINOIS LIVINGSTON... IN NORTHEAST ILLINOIS COOK... KANKAKEE... WILL... IN INDIANA THIS CANCELS 2 COUNTIES IN NORTHWEST INDIANA LAKE... PORTER... THIS INCLUDES THE CITIES OF...CHICAGO...GARY...JOLIET... KANKAKEE...PONTIAC AND VALPARAISO. ILZ033-039-INZ010>011-019-202300- FORD-IROQUOIS-BENTON-JASPER-NEWTON- 309 PM CDT WED JUL 20 2005 ...SEVERE THUNDERSTORM WATCH NUMBER 651 REMAINS VALID UNTIL 6 PM CDT... IN ILLINOIS THIS WATCH INCLUDES 2 COUNTIES IN EAST CENTRAL ILLINOIS FORD... IROQUOIS... IN INDIANA THIS WATCH INCLUDES 3 COUNTIES IN NORTHWEST INDIANA BENTON... JASPER... NEWTON... THIS INCLUDES THE CITIES OF...FOWLER...MOROCCO...PIPER CITY... RENSSELAER AND WATSEKA.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
321 PM CDT WED JUL 20 2005
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1245 PM TSTM WND DMG 2 E GRAYSLAKE 42.35N 88.00W
07/20/2005 LAKE IL EMERGENCY MNGR
TREES AND POWER LINES WERE BLOWN DOWN IN WILDWOOD AND
GRANDWOOD PARK. A CHIMNEY WAS BLOWN DOWN AND WIND
FLATTENED GRASS IN A FIELD. A SPOTTER AND A CITIZEN
REPORTED ROTATION. POSSIBLY A GUSTNADO.
0200 PM MARINE TSTM WIND 2 E CHICAGO 41.88N 87.59W
07/20/2005 46 MPH LMZ741 IL C-MAN STATION
HARRISON CRIB MEASURED A PEAK GUST TO 40 KNOTS.
&&
ALLSOPPSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 548 PM CDT WED JUL 20 2005 ILZ033-039-INZ010>011-019-210000- FORD-IROQUOIS-BENTON-JASPER-NEWTON- 548 PM CDT WED JUL 20 2005 ...THE NATIONAL WEATHER SERVICE HAS CANCELED SEVERE THUNDERSTORM WATCH 651 FOR THE FOLLOWING AREA... IN ILLINOIS THIS CANCELS 2 COUNTIES IN EAST CENTRAL ILLINOIS FORD... IROQUOIS... IN INDIANA THIS CANCELS 3 COUNTIES IN NORTHWEST INDIANA BENTON... JASPER... NEWTON... THIS INCLUDES THE CITIES OF...FOWLER...MOROCCO...PIPER CITY... RENSSELAER AND WATSEKA.
The Chicago radar (KLOT), 38 km away, was scanning. The volume nearest the first event began at 00:16 UTC.
6 thunderstorm wind, 1 lightning. Local standard time, as filed.
A gust to 69 mph was measured four miles northwest of Coal City.
Six inch diameter tree limbs were blown down near Coal City. A roof was blown off a barn and trees were blown over near Gardner.
Widespread tree damage was reported in Salina, Kankakee and St. Anne townships, including Kankakee City. A tree limb fell onto a parked van in Kankakee causing damage to the van. A large tree fell onto a garage in St. Anne causing extensive damage.
Large tree limbs were blown down.
Tree limbs and power lines were blown down.
Large tree limbs were blown down.
A lightning bolt struck a house and caused significant damage to the house and its contents. No one was injured.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2005Every state in 2005This day in weather historyWarnings in Illinois, July 2005
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: 5464201, 5464202, 5464286, 5464287, 5464289, 5464288, 5464290.