Severe storms moved across northern Illinois during the early morning hours of August 12th, producing wind damage.
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 storms moved across northern Illinois during the early morning hours of August 12th, producing wind damage.
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 Aug 11, 11:40 PM CST, 1 hour 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1240 AM CDT SUN AUG 12 2007 .DISCUSSION REGARDING AFTERNOON GRIDS/FCST... 335 PM CDT MAIN FCST CONCERNS THIS PERIOD ARE TRACKING OF EXPECTED MCS TO PASS MAINLY TO THE NORTH OF IL OVERNIGHT TNGT AND NEXT MCS EXPECTED TO DVLP ACROSS THE PLAINS AND PUSH INTO THE WESTERN GREAT LAKES MONDAY NIGHT INTO EARLY TUESDAY. 19Z SURFACE ANALYSIS SHOWING SPRAWLING HIGH PRES FROM LAKE HURON ACROSS LAKE ERIE INTO THE OHIO VALLEY. AS THIS AREA OF HIGH PRESSURE CONTINUES TO SLOWLY DRIFT EAST... BROAD SCALE SUBSIDENCE WITH THIS FEATURE HELPING TO MAINTAIN MAINLY CLEAR SKIES THIS EVENING DESPITE THIN CI CONVECTIVE DEBRIS MOVING OVER THE AREA. RETURN SOUTHERLY FLOW INCREASING RAPIDLY ACROSS NRN IL LATE THIS AFTERNOON AS SFC PRESSURE GRADIENT TIGHTENS IN THE WAKE OF DEPARTING SFC HIGH WITH RFD GUSTING TO 22 MPH AT 19Z. SFC DEW POINTS HAVE MIXED OUT LOWERING TO A SOMEWHAT MORE COMFORTABLE 62 TO 65 DEG F RANGE PER 20Z OBS... HOWEVER WITH SOUTHERLY FLOW INCREASING... AND DEW POINTS AROUND 70 ACROSS CENTRAL IL... EXPECT HIGHER DEW POINT AIR TO RETURN THIS EVENING. THIS WILL LIMIT FALL OF TEMPS OVERNIGHT AND HAVE GONE SLIGHTLY ABOVE GUIDANCE ON MINS. MAIN FORCING FOR CONVECTIVE DEVELOPMENT APPEARS TO BE WELL NORTH OF IL TNGT CLOSER TO FAST MOVING UPPER LEVEL SHORT WAVE TROUGH PROGGED TO PUSH INTO THE NORTHERN GREAT LAKES. AREA OF LOW LVL WARM AIR ADVECTION AND ISENTROPIC LIFT PER 310K THETA SURFACE PROGS BULLSEYED TO OUR NORTH CLOSER TO TRACK OF H850 LOW/TROUGH. MAY SEE BKN LINE OF CONVECTION DEVELOP FARTHER SOUTH ALONG WEAK SFC COLD FRONT EXTENDING TO THE SOUTHWEST OF THE PARENT LOW HOWEVER. THE SOUTHERN EXTENT OF SUCH A POSSIBLE LINE MAY BRUSH THE FAR NORTHERN SECTIONS OF IL LATE TNGT AFTER MIDNIGHT. WEAK COLD FRONT SAGS SOUTH INTO FAR NRN IL BY 12Z SUN AND THEN REACHES CLOSE TO I-80 BY 18Z. EXPECT BREAK IN PRECIPITATION CHANCES GIVEN MINIMAL LOW LEVEL CONVERGENCE ALONG THE BOUNDARY AND LACK OF ANY REAL UPPER LEVEL SUPPORT WITH FROPA DURING THE MORNING ON SUN. AS INSTABILITY INCREASES DURING THE AFTERNOON WOULD EXPECT TO SEE ISOLATED TO SCATTERED TSTMS DEVELOP ALONG THE BOUNDARY AS IT CONTINUES TO SAG SOUTH OF I-80 AND EXITS THE CWFA BY EVENING. 1024 MB SFC HIGH BUILDS INTO THE WESTERN GREAT LAKES BY 12Z MON WITH A MODEST NORTHEASTERLY FLOW ACROSS THE AREA. WITH INCREASING DRYING IN THE LOW LEVELS AND SUBSIDENCE ALOFT WILL EXPECT SKIES TO GENERALLY CLEAR SUN NIGHT. MONDAY LOOKS SOMEWHAT LIKE A REPEAT OF TODAY (SATURDAY) WITH A WEAK NE FLOW AND MODEST LAKE BREEZES. H850 TEMPS SIMILAR RANGING FROM 18-21 DEG C SO EXPECT MAXES TO REACH UPPER 80S ON MON. MORE INTERESTING SCENARIO DEVELOPING FOR MONDAY NIGHT AS SFC HIGH PRESSURE RIDGE DEPARTS FOR THE EASTERN GREAT LAKES. NEXT IN A SERIES OF UPPER LEVEL IMPULSES SLIDES ESE IN NW FLOW ALOFT ACROSS THE PLAINS INTO THE WESTERN GREAT LAKES. 45 KT LOW LVL JET PROGGED FOR MONDAY NIGHT OVER THE PLAINS COMBINED WITH FAVORABLE UPPER DYNAMICS SHOULD ENABLE MCS TO DEVELOP AND THEN TRACK ESE INTO NRN IL LATE MONDAY NIGHT/EARLY TUESDAY. WITH THIS FEATURE TRACKING QUITE A BIT FARTHER SOUTH THEN THE FIRST... JUST ABOUT ALL AREAS ALONG AND NORTH OF I-80 STAND A GOOD CHANCE FOR PCPN WITH DIMINISHING CHANGES AS ONE GOES SOUTH OF I-80. YET ANOTHER CHANCE FOR PRECIPITATION WILL COME WED AS THE WEAK SURFACE COLD FRONT ASSOCIATED WITH EARLY TUESDAYS MCS DROPS SOUTH OF THE FORECAST AREA AND STALLS SOUTH OF I-80. WITH YET ANOTHER UPR LVL SHORT WAVE GLIDING ACROSS VIA THE WNW FLOW ALOFT MAY BE SETTING UP A GOOD SCENARIO FOR OVERRUNNING ELEVATED CONVECTION FOR WED AND WED NIGHT. WITH THIS HAVE MAINTAINED CHC POPS THIS PERIOD., BOUNDARY PROGGED TO SAG FURTHER SOUTH THURSDAY. WITH THIS THOUGHT HAVE LEFT POPS OUT FOR NOW... HOWEVER A MORE NORTHERLY PRESENCE WOULD RESULT IN A CONTINUED CHC OF RAIN ACROSS NRN IL AND THIS WILL HAVE TO BE WATCHED CLOSELY. ED F && .AVIATION... 1240 AM CDT 06Z TAFS...MAIN CONCERN FOR THE OVERNIGHT HOURS WILL BE TIMING OF VISIBILITY TO DROP BELOW VFR AT THE TERMINAL SITES. LATEST SATELLITE AND RADAR IMAGERY INDICATING THAT THE LARGE CONVECTIVE LINE CONTINUES TO TRACK ESEWD THROUGH SRN WISCONSIN. BASED ON LATEST TRACK...DO NOT EXPECT THE LINE OF TS TO DIRECTLY IMPACT THE TERMINAL SITES...PERHAPS ONLY SKIRTING ALONG THE WI/IL BORDER. PRIMARY IMPACT OF THE TS WILL MOST LIKELY ONLY BE INCREASING CI COVERAGE. GIVEN THAT DEWPOINTS OVER THE REGION HAVE DROPPED INTO THE MIDDLE TO UPPER 60S AND INCREASING CI COVERAGE...DO NOT EXPECT VISIBILITY TO DROP INTO IFR RANGES OVERNIGHT...LIKELY REMAINING IN THE 4-5SM RANGE. FOR THE REMAINDER OF THE DAY...MAIN PROBLEM WILL BE TIMING THE WIND SHIFT WITH THE EXPECTED COLD FRONTAL PASSAGE. LATEST GUIDANCE INDICATES THAT THE FRONT WILL PASS SEWD THROUGH THE REGION DURG THE LATE AFTERNOON HOURS. THE BETTER INSTABILITY WILL BE FOCUSED OVER CNTRL IL/IN...SO EXPECT THAT THE FROPA WILL BE DRY. WITH THE FROPA...WINDS WILL QUICKLY VEER FROM SELY TO NLY AND NELY. KREIN && .MARINE DISCUSSION... 300 PM CDT WE EXPECT THE WIND SPEED TO INCREASE LATER TONIGHT. THE LOW IN CANADA WILL DEEPEN AND INCREASE THE PRESSURE GRADIENT BETWEEN IT AND THE HIGH OVER LAKE EIRE. THE COLD FRONT WILL BRING A WIND SHIFT ACROSS THE LAKE BY SUNDAY AFTERNOON. A HIGH WILL MOVE INTO LAKE MICHIGAN AND WE EXPECT THE WIND TO DECREASE FOR MONDAY THROUGH TUESDAY. TUESDAY NIGHT ANOTHER LOW WILL HAVE MOVED A COLD FRONT THROUGH LAKE MICHIGAN AND ANOTHER HIGH OVER CANADA WILL SPREAD INTO THE GREAT LAKES BY WEDNESDAY MORNING. WE USED THE GFS MODEL AND LOCALLY RUN WRF MODEL FOR THE WIND FORECAST. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 404 PM CDT SAT AUG 11 2007 ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 122115- 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- 404 PM CDT SAT AUG 11 2007 /504 PM EDT SAT AUG 11 2007/ THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA. .DAY ONE...TONIGHT. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS FAR NORTHERN ILLINOIS AFTER MIDNIGHT TONIGHT. OTHERWISE NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY. SCATTERED THUNDERSTORMS WILL DEVELOP ALONG A COLD FRONT ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA SOUTH OF I-80 SUNDAY AFTERNOON. THUNDERSTORMS ARE POSSIBLE MAINLY ALONG AND NORTH OF I-80 MONDAY NIGHT INTO TUESDAY MORNING. ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE ACROSS ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA ON WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO LMZ740>745-766-122115- 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- 404 PM CDT SAT AUG 11 2007 THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS AND INDIANA WATERS OF LAKE MICHIGAN. .DAY ONE...THIS AFTERNOON AND TONIGHT. THERE IS A CHANCE OF THUNDERSTORMS AFTER 2 AM TONIGHT. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY. THERE IS A CHANCE OF THUNDERSTORMS MONDAY NIGHT INTO TUESDAY MORNING.. AND AGAIN ON WEDNESDAY. && COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO WEBPAGE: WEATHER.GOV/CHICAGO ED F
The Milwaukee radar (KMKX), 89 km away, was scanning. The volume nearest the first event began at 07:09 UTC.
7 thunderstorm wind. Local standard time, as filed.
Tree branches and power lines blown down.
A 90 foot tall, 45 inch diameter tree was blown onto a house, causing significant damage to the roof, attic, a bathroom and a bedroom.
Measured wind gust to 62 mph.
Trees down at several locations across McHenry County.
A large tree was blown down.
Trees and power lines blown down across most of Lake County.
Tree limbs blown down at Route 25 and Army Trail Road.
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, August 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: 54785, 56767, 54790, 54786, 54787, 54788, 54789.