Severe thunderstorms moved south across northeast Illinois during the early morning hours of July 26th.
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.
Severe thunderstorms moved south across northeast Illinois during the early morning hours of July 26th.
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 26, 2:20 AM CST, 1 hour 21 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 320 AM CDT THU JUL 26 2007 .DISCUSSION... 320 AM CDT NOT MANY CHANGES MADE TO THE GOING FORECAST AS FOCUS THIS MORNING WAS KEEPING AN EYE ON THE RADAR AS STORMS HAVE BEEN DEVELOPING OVER THE LAKE AND MOVING INTO NW INDIANA. TWO STORMS SO FAR HAVE SHOWN MESO ROTATIONS GOING INTO PORTER COUNTY...BUT THEY HAVE BEEN FAIRLY LOW TOPPED WITH STORM TOPS AROUND 30KFT AND THE HIGHEST REFLECTIVITIES ONLY SHOOTING UP TO AROUND 15KFT. THESE STORMS...ALONG WITH CONVECTION DOWNSTREAM THRU CENTRAL INDIANA...IS ALL TIED TO A LOBE OF VORTICITY CYCLING ALONG THE NORTHWESTERN PERIPHERY OF THE CLOSED H5 LOW. AS THIS SHORTWAVE ROTATES SOUTHWARD...THE MAIN CIRCULATION OF THE LOW WILL PROPAGATE NORTHWARD INTO SOUTHERN MICHIGAN. WITH IT BEING AT ITS CLOSEST PROXIMITY...THERE WILL REMAIN A CHANCE FOR SHOWERS AND STORMS TO CONTINUE TO DEVELOP THROUGH THE DAY ON THURSDAY. SPC HAS PLACED A PORTION OF NE IL IN DAY 1 SLIGHT RISK...MAINLY DUE TO SOME POSSIBLE STORM INTERACTION WITH THE LAKE BREEZE THIS AFTERNOON. GIVEN THE LOW LEVEL WIND SHEAR PROFILE THAT SHOWS UP ON ACARS SOUNDINGS OUT OF OHARE...THE ONGOING STORMS THIS MORNING THAT HAVE SHOWN MESO-ROTATIONS...AND MODEST MUCAPE VALUES INTO THE 2000 J/KG RANGE...THIS SLIGHT RISK SEEMS WARRANTED. SEE SWODY1 FOR MORE DETAILS FROM SPC. OTHER MAIN FORECAST FOCUS WAS ON POP/WX OVER THE NEXT FEW DAYS AS A COLD FRONT DROPS DOWN THROUGH WISCONSIN TONIGHT. BY 12Z FRI...THIS FRONT SHOULD BE JUST TO THE NORTH OF THE STATE BORDER AND SHOULD SWING THROUGH THE REGION BY LATE FRIDAY NIGHT. WITH THE GULF OPENING UP...A DECENT PLUME OF STORMS SHOULD DEVELOP OUT AHEAD OF THE FRONT AND MOVE THROUGH THE REGION. PRECIPITABLE WATER VALUES CLIMB UP ABOVE 2 INCHES BY 12Z FRIDAY RIGHT AS A 30 TO 40KT LLJ KICKS IN FROM THE SW. BY MIDNIGHT...THE FRONT SHOULD BE INTO INDIANA AND NOT OF CONCERN FOR US ANYMORE. THE SEVERE THREAT STILL LOOKS MINIMAL WITH THIS FRONT AS THE TIMING OF FRONTAL PASSAGE IS NOT IDEAL WITH THE TIME OF DAY. AS FOR TEMPERATURES...BROUGHT DOWN THE MAX T ON FRIDAY AS CLOUD COVER AND MORNING RAINFALL WILL LIKELY LIMIT THE AMOUNT OF DAYTIME WARNING THAT CAN OCCUR. BEHIND THIS FRONT...HIGH PRESSURE WILL SETTLE IN ACROSS THE LAKES IN WHAT IS BECOMING A RECURRING THEME WEATHERWISE FOR THE MONTH OF JULY. HALBACH && .AVIATION... 1245 AM CDT / 06Z TAFS JET STREAK ROTATING AROUND SLOW MOVING UPPER LOW OVER NW OHIO IS STIRRING UP SHOWERS AND A FEW TSTMS OVER LK MICH INTO THE INDIANA SHORELINE. THIS ACTIVITY IS SLOWLY DEVELOPING WESTWARD WITH A FEW SHOWERS OFF SHORE FROM CHI. BROADER SCALE SYNOPTIC EVENTS WILL HALT THE WESTWARD DRIFT OF THIS ACTIVITY LATER THIS MORNING AND EXPECT ANY ORGANIZED SHOWERS OR TSTMS TO REMAIN EAST OF TAF SITES. MDW IS MOST VULNERABLE DURING PREDAWN AND EARLY MORNING HRS. CLOUDS HOLDING AT VFR LVLS THROUGH MOST OF THE MORNING INTO THE AFTERNOON. APPROACHING COOL FRONT FROM NW WILL ADD ANOTHER ELEMENT TO INCREASE SHOWER AND TSTM COVERAGE MAINLY LATE IN THE DAY AND TONIGHT. SOME MVFR WILL DEVELOP WITH INCR PRECIP ESPECIALLY AFTER SUNSET. SFC VSBYS MAY LOCALLY FALL TO 3-5 MI IN HAZE OR VERY LIGHT FOG TOWARD SUNRISE AND THAT REFLECTED IN RFD TAF. KL && .MARINE... 300 AM CDT THURSDAY SHOWERS AND THUNDERSTORMS OVER SOUTHERN LM ROATING AROUND LARGE UPPER LOW OVER NW OHIO. SOME OF THESE STORMS MAY PRODUCE WINDS TO 35 KTS. EXPECTED SHOWERS AND STROMS TO INCREASE NORTHWARD OVER THE LAKE TONIGHT AND FRIDAY AS A COOL FRONT APPROACHES FROM THE WEST AND UPPER LOW GRADUALLY RETREATS TO EAST. FRONT WILL PROGRESS SOUTHWARD THROUGH THE LAKE LATE FRIDAY AND FRIDAY NIGHT FOLLOWED BY HIGH PRESSURE OF 30.0 INCHES EXPECTED TO BUILD INTO THE WESTERN LAKES ON SATURDAY. NORTH AND NORTHEAST FETCH LATE FRIDAY AND SATURDAY MAY REQUIRE SCA FOR ILLINOIS AND INDIANA SHORES. RIP CURRENT THREAT WILL ALSO BE INCREASING FOR INDIANA SHORE ON SATURDAY. KML && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 415 AM CDT THU JUL 26 2007 ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 270915- 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- 415 AM CDT THU JUL 26 2007 /515 AM EDT THU JUL 26 2007/ THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA. .DAY ONE...TODAY AND TONIGHT. THUNDERSTORMS ARE POSSIBLE TODAY OVER MOST OF THE OUTLOOK AREA. THERE IS A SLIGHT CHANCE FOR SEVERE STORMS ACROSS NORTHERN ILLINOIS. THE MAIN THREAT WILL BE DAMAGING WINDS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY. THERE IS A CHANCE FOR THUNDERSTORMS FRIDAY INTO FRIDAY NIGHT. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO LMZ740>745-766-270915- WINTHROP HARBOR TO WILMETTE HARBOR IL- WILMETTE HARBOR TO NORTHERLY ISLAND IL- NORTHERLY ISLAND TO CALUMET HARBOR IL- CALUMET HARBOR IL TO GARY IN-GARY INDIANA TO BURNS HARBOR- BURNS HARBOR TO MICHIGAN CITY- LAKE MICHIGAN, WINTHROP HARBOR IL EASTWARD TO THE MID- POINT OF THE LAKE AND SOUTHWARD TO MICHIGAN CITY MI BEYOND 5 NM OFFSHORE- 415 AM CDT THU JUL 26 2007 THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS AND INDIANA WATERS OF LAKE MICHIGAN. .DAY ONE...TODAY AND TONIGHT. THERE IS A CHANCE OF THUNDERSTORMS TODAY THROUGH TONIGHT. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY. THERE IS A CHANCE OF THUNDERSTORMS FRIDAY INTO FRIDAY NIGHT. A SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY NIGHT INTO SATURDAY DUE TO HIGH WINDS AND WAVES. RIP CURRENTS ALSO MAY BE PRESENT ALONG THE INDIANA SHORES ON SATURDAY. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO HALBACH
The Chicago radar (KLOT), 20 km away, was scanning. The volume nearest the first event began at 09:40 UTC.
4 thunderstorm wind, 1 hail, 1 heavy rain. Local standard time, as filed.
Roof damage to two large commercial buildings. Numerous large limbs blown down. Damage concentrated near County Line Road and Interstate 55.
A microburst hit the Cedar Glen Subdivision in Homer Glen, east of Lockport. This is just northwest of the intersection of 159th Street and Cedar Road. There was scattered damage to trees throughout the neighborhood. Objects such as trampolines and lawn furniture were blown over as well. The most concentrated damage was in the east end of the subdivision along Cedar Glen Drive where several mature spruce trees were uprooted and some hardwood trees had large limbs or trunks snapped. A large portion of a roof of a house was torn off. Most of the damage was blown down from the northwest to southeast. In the west end of the neighborhood, some of the limbs were blown more to the south and southwest, in a downburst pattern. More than 30 trees were blown down at Old Oak Country Club.
Multiple trees blown down on Francis and Cedar Roads. Some trees across Francis Road.
One wall of a house was blown in by strong winds. Several trees and tree limbs were blown down.
Rainfall of 4.22 inches was measured between 7am and Noon.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2007Every state in 2007This day in weather historyWarnings in Illinois, July 2007
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: 52005, 52008, 52010, 52009, 52287, 52004.