Strong to severe thunderstorms moved across northern Illinois during the afternoon hours of July 31st.
Every event with a place to put it. 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.
Strong to severe thunderstorms moved across northern Illinois during the afternoon hours of July 31st.
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 31, 8:51 AM CST, 3 hours 14 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 951 AM CDT THU JUL 31 2008 .DISCUSSION... MORNING UPDATE... 951 AM CDT SOME SIGNIFICANT CHANGES TO GOING FORECAST THIS MORNING...FOCUSING ON HEIGHTENED SEVERE WEATHER THREAT ACROSS THE FORECAST AREA THIS AFTERNOON. MCS CURRENTLY PROPAGATING ACROSS SOUTHEAST MN/NORTHEAST IA EXPECTED TO CONTINUE TO TRACK SOUTHEAST TOWARD NORTHERN IL/NORTHWEST IN BY AFTERNOON IN ASSOCIATION WITH MID LEVEL TROUGH AND 40 KNOT SPEED MAX DEPICTED BY MORNING RAOB ANALYSIS/CURRENT GOES VAPOR IMAGERY. DIFFUSE STATIONARY FRONT WHICH SAGGED INTO AREA YESTERDAY REMAINS ACROSS THE CWA...WITH LATEST VIS SAT PICS SUGGESTING BOUNDARY CURRENTLY FROM NORTH OF KDBQ...KRPJ...KJOT...SOUTH OF KVPZ LINE. SURFACE DEW POINT TEMPS IN THE LOWER 70S ALONG/SOUTH OF THIS BOUNDARY EXPECTED TO RESULT IN UNSTABLE BOUNDARY LAYER AS HEATING CONTINUES FOR REMAINDER OF MORNING/AFTERNOON HOURS AND STRATUS/FOG ACROSS SOUTHERN HALF OF SO OF FORECAST AREA DISSIPATES. GIVEN FOCUS ALONG BOUNDARY AND SIGNIFICANT INSTABILITY AXIS...EXPECT MCS TO CONTINUE TO PROPAGATE INTO CWA BY MIDDAY/EARLY AFTERNOON AND WILL LIKELY REINTENSIFY. THUS HAVE AMENDED FORECAST TO INCLUDE THUNDERSTORMS INTO FAR NORTHWEST COUNTIES BY MIDDAY AND ACROSS REMAINDER OF CWA THIS AFTERNOON. RATZER PREVIOUS DISCUSSION... 330 AM CDT MAIN CONCERN FOR THE SHORT TERM WILL BE CONVECTION POTENTIAL FOR TONIGHT. BEYOND THIS...THE FOCUS WILL...ONCE AGAIN...SHIFT TO INCREASING HEAT IN THE LONG TERM FORECAST PERIOD. FOR THIS EVENING...LOOKING AT INCREASED POTENTIAL FOR MCS DEVELOPMENT AND TRACKING OUT OF THE NRN PLAINS/UPPER MISSISSIPPI VALLEY AND INTO NWRN ILLINOIS. THIS WILL LIKELY BE AN ARTIFACT OF THE CURRENT MCS ACTIVITY OVER THE DAKOTAS. EXPECT THAT RENEWED MCS SHOULD FIRE IN ASSOCIATION WITH BOUNDARIES SET DOWN BY THE CURRENT ACTIVITY OVER THE DAKOTAS. ALSO...IN THE SYNOPTIC SCALE...SHORT WAVE ENERGY WILL DIVE DOWN THE BACK SIDE OF THE BUILDING UPPER RIDGE AND FOLLOW THE PREFERRED THICKNESS CHANNEL AND UPPER DIFLUENCE THROUGH NERN IOWA AND INTO NWRN ILLINOIS THIS EVENING. BASED ON THIS AND GENERAL MODEL CONSENSUS FOR THE SYNOPTIC SCALE FLOW PATTERN...PLUS A WARM/MOIST/UNSTABLE ENVIRONMENT IN PLACE...HAVE INCREASE POPS OVER NORTH CENTRAL ILLINOIS TO LIKELY TO REFLECT THIS IDEA. BEYOND THIS...THE FOCUS WILL SHIFT TO THE HEAT THAT HAS BEEN ADVERTISED FOR THE PAST FEW DAYS. THE LATEST MODEL RUNS CONTINUE THE TREND OF LAST NIGHT/S GUIDANCE IN DELAYING THE ONSET OF THE HEAT UNTIL SUNDAY AND MONDAY. THE LATEST GUIDANCE SHOWS RELATIVELY DECENT CONTINUITY WITH LAST NIGHT/S GUIDANCE IN TRENDING TOWARD A MORE AMPLIFIED AND LESS PROGRESSIVE PATTERN THAN WAS ADVERTISED A COUPLE DAYS AGO. THUS...SATURDAY WILL LIKELY SEE TEMPERATURES ONLY CLIMB TO AROUND 90...WHILE THE MORE EXTREME HEAT WILL MOVE IN ON SUNDAY AND MONDAY AS THE MAIN RIDGE AXIS MOVES OVER THE UPPER MIDWEST. THE 00Z GFS SHOWS 850MB TEMPS REACHING AROUND 25C...WHICH WOULD SUGGEST THAT TEMPS SHOULD REACH INTO THE MIDDLE TO UPPER 90S. THUS HAVE NUDGED UP MAX TEMPS A FEW DEGREES OVER THE GOING FORECAST. COMBINED WITH DEWPOINTS IN THE UPPER 60S TO MIDDLE 70S...HEAT INDEX READING WILL LIKELY REACH OR EXCEED 100F OVER MUCH OF THE AREA. WHILE IT IS TOO SOON FOR HEADLINES JUST YET...HEAT ADVISORIES WILL LIKELY BE REQUIRED BY SUNDAY OR MONDAY. KREIN && .AVIATION... 1200 UTC TAFS...AM SUSPECTING WITH LINE OF CU AT SUNSET THAT OLD BOUNDARY THAT FIRED UP SHOWERS THIS AFTN IN NRN IL/NWRN IN IS STILL THERE RUNNING FROM WEST OF RFD TO SOUTH OF GYY. DEWPTS IN 70S ACRS THOSE AREAS...HIGHLITING A GOOD MSTR SOURCE. ALL WE NEED IS A TRIGGER THIS AFTN TO FIRE OFF MORE TSTMS. THERE APPEARS TO BE SEVERAL SOURCES FOR THIS. FIRST WITH WEAK NW SFC FLOW TODAY AS A RESULT OF LYING IN A CANYON BETWEEN TWO AREAS OF LOW PRESSURE... WILL NOT HAVE MUCH TO KEEP A LAKE BREEZE FROM KICKING IN AFTER CLIMBING THRU THE 80S. THIS WILL AFFORD ANOTHER BOUNDARY MOVING INLAND AND CONVERGING WITH OLD BOUNDARY MENTIONED ABOVE. SECONDLY THE CONVECTIVE TEMP FOR FIRING CONVECTION IS AROUND 85 AS INDICATED ON FCST SOUNDINGS. THE FCST HIGH IS IN THE THE UPPER 80S. THIRDLY...MODELS INDICATING A WEAK MID LVL WAVE DIVING DOWN UPR NW FLOW NEARING SUNSET. MCS ACTIVITY VSBL ON MOSAIC ENTERING WRN MN NOW JUST AHEAD OF THIS WAVE. THIS NEARING NW IL THIS AFTN WITH BEST CHANCES FOR STRIKING N CNTL IL. WILL REVERSE PREVIOUS TSTM PROB LOCATIONS AND PLACE IN RFD VCTS BUT NOT INSERT IN ORD OR MDW OR GYY AT THIS TIME. BUT BELIEVE THAT IS A SMALL CHANCE WILL BE NEAR THE LAKE BREEZE. WITH ENVIRONMENTAL NW TO N FLOW...THINK THAT LAKE BREEZE WILL NOT MAKE IT INTO DPA AND RFD. THEN WINDS DROPPING OFF THE L/V AGAIN AFTER DARK WITH MVFR FOG LIKELY TO DEVELOP THURS NGT ESP FOR DPA AND RFD WITH OTHERWISE VFR CIGS. RLB && .MARINE... 259 AM CDT LOW PRESSURE WILL ANCHOR OVER SOUTHERN QUEBEC THROUGH SUNDAY WITH A SERIES OF HIGHS AND LOW ALTERNATING OVER THE LAKES THRU THAT PERIOD. WEAK HIGH PRESSURE WILL MOVE ACROSS THE WESTERN LAKES LATER TODAY BEFORE A WEAK AREA OF LOW PRESSURE DEVELOPS ACROSS THE CENTRAL PLAINS AND MOVES ACROSS LAKE MICHIGAN ON FRIDAY. THEN ANOTHER WEAK AREA OF HIGH PRESSURE WILL MOVE ACROSS THE WESTERN LAKES LATE SATURDAY AND SATURDAY NIGHT...AS LOW PRESSURE DEVELOPS OVER THE PLAINS. THIS RATHER WEAK AREA OF LOW PRESSURE WILL MOVE INTO THE WESTERN LAKES MONDAY. WINDS THROUGH THE WEEKEND WILL BE RATHER LIGHT WITH DIRECTIONS REVOLVING AROUND THE CLOCK AND AT TIME BECOMING LIGHT AND VARIABLE. THUS NO GALES ARE IN JEOPARDY OF APPEARING. RLB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1001 AM CDT THU JUL 31 2008 ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 011515- WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE- DUPAGE-COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON- IROQUOIS-FORD-LAKE INDIANA-PORTER-NEWTON-JASPER-BENTON- 1001 AM CDT THU JUL 31 2008 /1101 AM EDT THU JUL 31 2008/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL ILLINOIS...NORTHEAST ILLINOIS AND NORTHWEST INDIANA. .DAY ONE...TODAY AND TONIGHT. WEATHER HAZARDS EXPECTED: THUNDERSTORMS SOME MAY PRODUCE: DAMAGING WINDS IN EXCESS OF 70 MPH. PENNY SIZED HAIL. FREQUENT LIGHTNING. HEAVY RAINFALL AND LOCALIZED FLOODING. AREAS AFFECTED AND TIMING: A THUNDERSTORM COMPLEX ACROSS SOUTHERN MINNESOTA AND NORTHERN IOWA WILL MOVE INTO SOUTHERN WISCONSIN AND FAR NORTHERN ILLINOIS EARLY THIS AFTERNOON...AND THEN ACROSS THE REMAINDER OF THE OUTLOOK AREA INCLUDING AREAS SOUTH OF INTERSTATE 80 DURING THE MID AND LATE AFTERNOON HOURS. ADDITIONAL THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS NORTHERN IOWA AND SOUTHEAST MINNESOTA THIS EVENING...AND MOVE INTO NORTHERN ILLINOIS DURING THE OVERNIGHT HOURS. DISCUSSION: SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN MINNESOTA AND NORTHERN IOWA ARE EXPECTED TO TRACK SOUTHEAST THROUGH THE AFTERNOON HOURS ALONG A FRONTAL BOUNDARY STALLED ACROSS NORTHERN ILLINOIS. THESE THUNDERSTORMS MAY WEAKEN ACROSS EASTERN IOWA AND SOUTHWEST WISCONSIN LATE THIS MORNING...BUT ARE EXPECTED TO INTENSIFY ONCE AGAIN THIS AFTERNOON AS DAYTIME HEATING ALLOWS UNSTABLE CONDITIONS TO DEVELOP ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS. THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS EVENING ACROSS SOUTHERN MINNESOTA AND NORTHERN IOWA IN ADVANCE OF AN APPROACHING FRONTAL BOUNDARY. THESE THUNDERSTORMS ARE EXPECTED TO MOVE ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA OVERNIGHT AND MAY ALSO POSE A SEVERE RISK...MAINLY IN THE FORM OF DAMAGING WINDS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY. A STRONG UPPER LEVEL RIDGE BUILDING ACROSS THE PLAINS AND INTO THE MIDWEST WILL BRING THE HIGHEST TEMPERATURES OF THE SUMMER TO THE REGION. TEMPERATURES MAY CLIMB INTO THE MIDDLE 90S BY SUNDAY AND THE MIDDLE TO UPPER 90S BY MONDAY. COMBINED WITH HIGH HUMIDITY...THE HEAT INDEX MAY EXCEED 100 DEGREES SUNDAY AND MONDAY. .SPOTTER INFORMATION STATEMENT... SPOTTERS WILL LIKELY BE NEEDED THIS AFTERNOON AND TONIGHT. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO LMZ740>745-011515- 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- 1001 AM CDT THU JUL 31 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE ILLINOIS NEARSHORE WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE WATERS OF LAKE MICHIGAN. .DAY ONE...TODAY AND TONIGHT. THERE IS A CHANCE OF THUNDERSTORMS THIS AFTERNOON AND TONIGHT. SOME STORMS MAY PRODUCE WINDS IN EXCESS OF 35 KNOTS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY. THERE IS A CHANCE OF THUNDERSTORMS FRIDAY MORNING. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868- 870-872-874-876-878-011515- LAKE MICHIGAN FROM MICHIGAN CITY IN TO ST. JOSEPH MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM SEUL CHOIX POINT TO ROCK ISLAND PASSAGE 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN SOUTH OF A LINE FROM SEUL CHOIX POINT TO THE MACKINAC BRIDGE AND NORTH OF A LINE FROM CHARLEVOIX MI TO SOUTH FOX ISLAND 5 NM OFFSHORE- LAKE MICHIGAN FROM CHARLEVOIX TO POINT BETSIE MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM POINT BETSIE TO MANISTEE MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM ROCK ISLAND PASSAGE TO STURGEON BAY WI- LAKE MICHIGAN FROM STURGEON BAY TO TWO RIVERS WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM TOW RIVERS TO SHEBOYGAN WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM SHEBOYGAN TO PORT WASHINGTON WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM PORT WASHINGTON TO NORTH POINT LIGHT WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM NORTH POINT LIGHT TO WIND POINT WI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WIND POINT WI TO WINTHROP HARBOR IL 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WINTHROP HARBOR TO WILMETTE HARBOR IL 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WILMETTE HARBOR IL TO MICHIGAN CITY IN 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM PENTWATER TO MANISTEE MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM WHITEHALL TO PENTWATER MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM GRAND HAVEN TO WHITEHALL MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM HOLLAND TO GRAND HAVEN MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM SOUTH HAVEN TO HOLLAND MI 5 NM OFFSHORE TO MID LAKE- LAKE MICHIGAN FROM ST. JOSEPH TO SOUTH HAVEN MI 5 NM OFFSHORE TO MID LAKE- 1001 AM CDT THU JUL 31 2008 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE OPEN WATERS OF LAKE MICHIGAN. .DAY ONE...TODAY AND TONIGHT. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND TONIGHT. SOME OF THE STORMS MAY PRODUCE WINDS IN EXCESS OF 35 KNOTS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY. THERE IS A CHANCE OF THUNDERSTORMS OVER LAKE MICHIGAN FRIDAY. SOME STORMS MAY PRODUCE WINDS IN EXCESS OF 35 KNOTS. THERE IS A CHANCE OF THUNDERSTORMS AGAIN SUNDAY NIGHT. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO MARSILI
The Milwaukee radar (KMKX), 69 km away, was scanning. The volume nearest the first event began at 18:06 UTC.
13 thunderstorm wind. Local standard time, as filed.
A tree was blown down along Dorr Road, blocking half of the road.
Shingles were blown off of a roof and a small peach tree was snapped off one foot above the ground, both in Machesney Park.
Wind gusts were estimated to 60 mph one mile north of Winnebago.
Large healthy trees were blown down along Route 2, roughly three miles south of Oregon.
A wind gust to 66 mph was measured in Mount Morris.
Arm size tree limbs were blown down.
Trees and power lines were blown down.
A light pole was blown down in a parking lot along Northwest Highway. The light pole struck four parked cars.
Two large trees were snapped off about 15 feet above ground. One of the trees fell onto a tree house, which was destroyed.
A tree was blown down.
A wind gust to 62 mph was measured near Route 72 and Randall Road.
A tree was blown down.
Trees were blown down in the 6100 block of East Birmingham Street.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2008Every state in 2008This day in weather historyWarnings in Illinois, July 2008
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: 124328, 124329, 124338, 124330, 124339, 124331, 124332, 124333, 124334, 124335, 124340, 124336, 124337.