A line of heavy rain-producing thunderstorms dropped southward through parts of northwest Illinois during the evening hours of July 27 and early morning hours of July 28. A few of the storms produced wind gust up to 60 mph.
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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 DVN wrote it up.
A line of heavy rain-producing thunderstorms dropped southward through parts of northwest Illinois during the evening hours of July 27 and early morning hours of July 28. A few of the storms produced wind gust up to 60 mph. The heavy rains associated with the storms resulted in some flash flooding in Carroll and Whiteside Counties. In addition, some non-severe hail fell near Savanna, IL around 940 pm.
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 Quad Cities, IA wrote its last area forecast discussion before the first event at Jul 27, 1:59 PM CST, 5 hours 56 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 259 PM CDT MON JUL 27 2009 .SYNOPSIS... SFC LOW SOUTH OF KMSP WITH COLD FRONT EXTENDING SWWD NEAR A LINE FROM ALGONA IA TO SIOUX CITY IA TO NORTH PLATTE NE. AIRMASS MODERATE TO STRONGLY UNSTABLE AHEAD OF FRONT AND SFC LOW WITH SBCAPES RANGING FROM 1500-3000 J/KG AND LI/S OF -3 TO -7 WITH GREATEST INSTABILITY LOCATED ACROSS NORTHERN CWA AND AREAS FURTHER N/W. CONVECTION WAS DEVELOPING JUST DOWNSTREAM OF SFC LOW ACROSS WESTERN WI... AND VIGOROUS SHORTWAVE OVER NORTHWEST WI DENOTED BY PRONOUNCED DRYING IN WATER VAPOR IMAGERY. UPPER LOW WAS CHURNING OVER FAR EASTERN MANITOBA AND WESTERN ONTARIO WITH AREA REMAINING IN NORTHWEST FLOW WITH MANY IMPULSES WORKING E/SE IN THE FLOW. OTHER MORE NOTABLE WAVES WERE LOCATED OVER SOUTHEAST NE AND ASSOCIATED WITH BAND OF SHRA INTO SOUTHWEST IA WITH NEWLY DEVELOPED CONVECTION OVER KS. MUCH STRONGER WAVE WAS DIVING DOWN BASE OF LONGWAVE TROUGH AND PASSING ACROSS THE NORTHERN ROCKIES. && .SHORT TERM...TONIGHT AND TUESDAY... MAIN CHALLENGE IS POPS THROUGH THE PERIOD AND SEVERE WX POTENTIAL MAINLY THIS EVE. SHORT FUSE METHOD SUGGESTS MORE WIDESPREAD AND ORGANIZED SEVERE CONVECTION WILL RESIDE JUST NORTH OF CWA AHEAD OF SFC LOW FROM FAR SOUTHEAST MN THROUGH SOUTHERN WI IN ZONE OF MID LEVEL DRYING AND STRONGER SHEAR WITH ATTENDANT MID LEVEL SHORTWAVE. ADDITIONAL CONVECTIVE DEVELOPMENT POSSIBLE ALONG THE FRONT BUT CONVERGENCE DIMINSHING WITH FLOW VEERING TO WESTERLY JUST AHEAD OF BOUNDARY... AND SO COVERAGE MAY BE MORE SCTD. HIGHEST POPS FOR THIS EVE WILL BE ACROSS THE NORTH. SUFFICIENT SHEAR (0-6KM OF 30 KTS) AND INSTABILITY TO SUPPORT SEVERE POTENTIAL WITH ANY STORMS THAT SHOULD DEVELOP. BEYOND THIS EVE... PCPN CHCS WILL EXIST AHEAD OF THE FRONT... JUST UNSURE ABOUT COVERAGE AS VARYING SIGNALS EXIST AMONG MODELS. EXPECT THOUGH BEST PCPN CHCS OVERNIGHT INTO TUE WILL BE FOCUSED SOUTHERN 1/2. ..05.. .LONG TERM...TUESDAY NIGHT THROUGH MONDAY... NOT MUCH DIFFERENCE IN THE LONG TERM CHALLENGES TODAY FROM THE PREVIOUS SEVERAL DAYS. UPPER LOW REMAINS ANCHORED OVER THE EASTERN PROVINCES...WITH A STREAM OF WAVES IN NORTHWEST FLOW OVER THE UPPER MIDWEST. OVERALL CONFIDENCE REMAINS LOW BEYOND 72 HOURS AND TIMING WAVES AND BOUNDARIES IS KEY. BY TUESDAY NIGHT THE FRONT HAS CLEARED THE AREA AND PAVES THE WAY FOR A NICE DAY WEDNESDAY. GFS PERSISTS IN BRINGING ANOTHER FRONT THROUGH THURSDAY. WHILE IT STILL APPEARS OVERDONE...IT IS THE ONLY MODEL THAT HAS CONSISTENTLY BROUGHT A BOUNDARY INTO THE AREA THURSDAY. NAM AND ECMWF HAVE NOW MOVED INTO AGREEMENT WITH THE GFS AND WILL FAVOR THE GENERAL GFS SOLUTION FOR THURSDAY THROUGH THE WEEKEND. 850 MB THERMAL TROUGH OVER UPPER MISSISSIPPI VALLEY ON THURSDAY SUGGESTS A COOLER DAY AND HAVE TRENDED TEMPS DOWN. WITH NO SIGNIFICANT CHANGE EXPECTED TO THE UPPER PATTERN...THE NEXT FRONT IS ON TAP FOR SATURDAY INTO SUNDAY. WILL KEEP CHANCE POPS FOR NOW UNTIL DETAILS CAN BE RESOLVED. ..33.. && .AVIATION... SFC LOW OVER SOUTHEAST MN WILL MOVE E/SE TONIGHT SENDING A COLD FRONT ACROSS THE TERMINALS LATER THIS EVE INTO EARLY TUE MORNING. GUSTY SOUTHWEST WINDS TO VEER TO DIMINISH AOB 10 KTS WHILE VEERING TO THE NORTHWEST. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE FOUND WITH THE FRONT WHERE POTENTIAL EXISTS FOR PERIOD OF MVFR CONDITIONS WITH PCPN. PCPN CHCS GRADUALLY DIMINISH OVERNIGHT INTO TUE FROM NORTH TO SOUTH ACROSS TERMINALS WITH PASSAGE OF SFC AND H85 FRONTS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && 05/33
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 353 PM CDT MON JUL 27 2009 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-281000- BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON- CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON- HENRY IA-DES MOINES-VAN BUREN-LEE-JO DAVIESS-STEPHENSON-CARROLL- WHITESIDE-ROCK ISLAND-HENRY IL-BUREAU-PUTNAM-MERCER-HENDERSON- WARREN-HANCOCK-MCDONOUGH-SCOTLAND-CLARK- 353 PM CDT MON JUL 27 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL ILLINOIS...NORTHWEST ILLINOIS...WEST CENTRAL ILLINOIS...EAST CENTRAL IOWA...NORTHEAST IOWA...SOUTHEAST IOWA AND NORTHEAST MISSOURI. .DAY ONE...THIS AFTERNOON AND TONIGHT THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING NORTH OF A LINE FROM MOUNT PLEASANT IOWA TO GENESEO ILLINOIS. ISOLATED TO SCATTERED THUNDERSTORMS AHEAD OF A COLD FRONT WILL MOVE ACROSS NORTHEAST IOWA AND NORTHWEST ILLINOIS LATE THIS AFTERNOON AND EVENING. AN ISOLATED SEVERE STORM CANNOT BE RULED OUT... MAINLY ALONG AND NORTH OF HIGHWAY 20 UNTIL SUNSET. THE PRIMARY THREATS WILL BE HAIL UP TO THE SIZE OF QUARTERS AND WIND GUSTS OVER 60 MPH. THUNDERSTORMS OVERNIGHT ARE NOT EXPECTED TO BE SEVERE...BUT MAY PRODUCE LOCALLY HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF THE OUTLOOK AREA TUESDAY THROUGH TUESDAY NIGHT...IN CONJUNCTION WITH A SLOW MOVING COLD FRONT. SEVERE STORMS ARE NOT EXPECTED WITH THIS ACTIVITY. THERE IS ANOTHER CHANCE FOR THUNDERSTORMS OVERNIGHT WEDNESDAY NIGHT INTO THURSDAY...AND AGAIN AS ANOTHER FRONT IS FORECAST TO MOVE THROUGH DURING THE WEEKEND. AT THIS TIME SEVERE STORMS ARE NOT ANTICIPATED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS POSSIBLE LATE THIS AFTERNOON AND EVENING FOR PORTIONS OF EASTERN IOWA AND NORTHWEST ILLINOIS.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
339 PM CDT MON JUL 27 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0921 PM TSTM WND DMG COLONA 41.49N 90.35W
07/24/2009 HENRY IL LAW ENFORCEMENT
TREE BLOWN DOWN BY WIND FELL ON A VAN CAUSING AN INJURY
TO AN OCCUPANT REQUIRING TRANSPORT TO THE HOSPITAL.
&&
WOLFThe Quad Cities radar (KDVN), 96 km away, was scanning. The volume nearest the first event began at 01:55 UTC.
4 thunderstorm wind, 3 flash flood, 1 hail. Local standard time, as filed.
Wind gusts were estimated to be 50 to 60 mph about 3 miles northwest of Stockton, IL at 855 pm July 27.
Wind gusts were estimated to be 60 mph in Freeport, IL around 920 pm July 27. This report was relayed by a local media station.
Wind gusts estimated to be 70 mph blew down about 10 trees at the Manus residence on S. Hollywood Drive on the south end of Freeport, IL around 920 pm July 27.
Heavy rains caused some flash flooding of some streets in Freeport, IL during the late evening hours of July 27. Several traffic signals were disabled.
Wind gusts were estimated to be 50 to 60 mph about 1 mile east northeast of Shannon, IL at 944 pm July 27.
Heavy rains resulted in flash flooding near Mount Carroll, IL during the evening hours of July 27 and the early morning hours of July 28. Roads were closed due to the high water. In particular, Scenic Bluff Road was barricaded by law enforcement officials around 1023 pm.
Heavy rains resulted in flash flooding in Fulton, IL during the evening hours of July 27 and the early morning hours of July 28. Some intersections in town were flooded around 1124 pm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2009Every state in 2009This day in weather historyWarnings in Illinois, July 2009
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: 189289, 189291, 191648, 191653, 189292, 189293, 189300, 189308.