Heavy rain fell across parts of northern Illinois which caused some flooding.
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.
Heavy rain fell across parts of northern Illinois which caused some flooding.
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 May 26, 6:13 PM CST, 13 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 713 PM CDT TUE MAY 26 2009 .DISCUSSION... 320 PM CDT NEAR TERM FOCUS REMAINS ON PRECIP/CONVECTION TRENDS THROUGH WEDNESDAY ASSOCIATED WITH LOW PRESSURE SYSTEM DRIFTING THROUGH THE MIDWEST. SURFACE LOW PRESSURE LOCATED OVER FAR NORTHEAST MISSOURI AT 19Z...WITH WARM FRONT EXTENDING EAST ACROSS SOUTHERN LOT CWA COUNTIES. AIRMASS SOUTH OF WARM FRONTAL BOUNDARY IS MOIST AND UNSTABLE WITH SPC/RUC MLCAPE VALUES IN 1000-1500 J/KG RANGE. SHORT WAVE TROUGH NOTED IN PROFILER/VAPOR DATA ACROSS EASTERN MISSOURI...LIFTING NORTH AROUND MAIN MID LEVEL CIRCULATION ALONG IA/MO BORDER. COMBINATION OF UNSTABLE AND UNCAPPED LOW LEVELS AND FORCING ASSOCIATED WITH MID LEVEL WAVE IS RESULTING IN SCATTERED THUNDERSTORMS DEVELOPING ACROSS ABOUT SOUTHERN 3/4 OR SO OF CWA. WINCHESTER PROFILER WINDS AROUND 4KM/700 HPA HAVE INCREASED TO ABOUT 30 KTS LAST FEW HOURS RESULTING IN SLIGHT INCREASE IN DEEP LAYER SHEAR. SPC DAY 1 OUTLOOK DOES INDICATE 2% TORNADO THREAT ACROSS PART OF NORTHERN IL AND WHILE THREAT APPEARS MINIMAL...THIS SYSTEM HAS A HISTORY OF PRODUCING NON-SUPERCELL FUNNELS/TORNADOES OVER THE PAST COUPLE OF DAYS. WITH MOIST/UNSTABLE AIRMASS AND MODEST SPEED MAX OVER THE AREA WILL HAVE TO MONITOR RADAR TRENDS FOR THE POTENTIAL FOR ISOLATED BRIEF TORNADOES ESPECIALLY WHERE LOW LEVEL SHEAR MAY BE LOCALLY HIGHER ALONG WARM FRONT. UPPER LOW PROGGED TO LIFT ACROSS EASTERN IOWA AND INTO WISCONSIN THROUGH WEDNESDAY MORNING. MAIN AREA OF NON-DIURNAL RAINFALL CURRENTLY ACROSS IA/WI EXPECTED TO CONTINUE TO OCCUR IN VICINITY OF THIS FEATURE...WHILE CONVECTIVE ACTIVITY ACROSS IL/IN EXPECTED TO BE MORE TIED TO DIURNAL INSTABILITY CYCLE THIS EVENING AND AGAIN ON WEDNESDAY AS TRAILING FRONT MOVES ACROSS FORECAST AREA. THUS HAVE ADJUSTED POPS/QPF AMOUNTS TO FOCUS A BIT MORE TO THE NORTH OF CWA THROUGH WEDNESDAY...ACROSS WI/LAKE MICHIGAN. THIS MAINTAINS IDEA OF GREATEST OVERALL RAINFALL OVER NORTHWESTERN PARTS OF CWA/NORTH CENTRAL IL...WITH AMOUNTS NEAR AN INCH. OBVIOUSLY...CONVECTIVE NATURE OF PRECIP ACROSS REMAINDER OF AREA WILL NEED TO BE MONITORED FOR ANY POTENTIAL TRAINING OF SLOW MOVING CELLS...BUT OVERALL FLOOD THREAT DOES NOT APPEAR OVERLY SUBSTANTIAL. HAVE BACKED OFF POPS A BIT WEDNESDAY NIGHT/EARLY THURSDAY AS FRONT SHIFTS OFF TO THE EAST AND INITIAL UPPER WAVE MOVES OUT OF THE AREA...THOUGH WILL MAINTAIN AT LEAST LOW CHANCE POPS WITH BAGGY MID LEVEL TROUGH STILL PROPAGATING ACROSS THE REGION THURSDAY MORNING. IN EXTENDED FORECAST...MODELS HAVE COME INTO A LITTLE BETTER FOCUS WITH WAVES DROPPING THROUGH NORTHWEST FLOW INTO EASTERN NOAM TROUGH BY THE WEEKEND. STILL SOME DIFFERENCES IN DETAILS WITH REGARD TO TIMING OF WARM/COLD FRONTAL PASSAGES...WITH FORECAST AREA ON SOUTHERN FRINGE OF GREATER PRECIPITATION POTENTIAL. FOR NOW HAVE INCLUDED SOME LOW CHANCE POPS SATURDAY/SUNDAY...INCREASING MONDAY/TUESDAY AS COLD FRONT SAGS ACROSS FORECAST AREA. RATZER && .AVIATION... 705 PM CDT 0000 UTC TAFS...CONVECTIVE TRENDS AND DETERIORATING VSBYS CIGS WILL BE THE MAIN AVIATION FORECAST ISSUES. SURFACE WARM FRONT APPEARS TO BE HAVE SLOWED SOMEWHAT AND BASED ON RADAR IMAGERY AND SURFACE OBSERVATIONS LIES ROUGHLY FROM VYS TO IKK. A RATHER SHARP CUT OFF IN THE MAGNITUDE OF INSTABILITY EXISTS WITH THE WARM FRONT WITH INSTABILITY WEAKER ACROSS FAR NORTHERN ILLINOIS. WIDESPREAD RAIN SHOWERS AND EMBEDDED THUNDERSTORMS CONTINUE NORTH OF THE WARM FRONT ACROSS MUCH OF NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS FRONT SHOULD CONTINUE NORTHWARD THROUGH THE EVENING HOURS RESULTING IN INCREASING ELEVATED INSTABILITY AND A CONTINUED CHANCE OF EMBEDDED THUNDER. HAVE SOME CONCERN THAT MOST COMPUTER MODEL GUIDANCE MAY BE MOVING WARM FRONT NORTHWARD TOO QUICKLY GIVEN WIDESPREAD RAINFALL NORTH OF THE FRONT AND NORTHEAST FLOW OFF THE COLD LAKE MICHIGAN WATERS. CURRENT THINKING IS THAT WARM FRONT MAY HAVE A HARDER TIME CLEARING FROM NORTHERN ILLINOIS. HAVE ONLY CARRIED MENTION OF THUNDER THROUGH 02Z...BUT CONTINUED MENTION OF SHOWERS THROUGH 06Z AS WARM FRONT CONTINUES TO ADVANCE NORTHWARD. IFR CIGS ARE BEGINNING TO DEVELOP NORTH OF THE WARM FRONT AND EXPECTING IFR CONDITIONS TO BECOME WIDESPREAD BY THE 03Z TO 04Z TIME FRAME. VSBYS ALSO WILL BECOME A CONCERN FOR THE OVERNIGHT WITH A RELATIVELY WEAK GRADIENT SETTING UP ACROSS THE AREA AND A ZONE OF WEAK SFC MOISTURE CONVERGENCE ASSOCIATED WITH THE FRONT. IFR VSBYS WITH FOG STILL SEEM REASONABLE AT THIS TIME. CONDITIONS SHOULD IMPROVE TO LOWER END MVFR BY LATE MORNING TOMORROW. ALTHOUGH HAVE CONFINED MENTION OF PRECIP TO TONIGHT...MAY NEED TO CONSIDER ADDING MORE SHOWERS TO FORECAST IN FUTURE FORECASTS FOR WEDNESDAY AS SECONDARY UPPER TROUGH MOVES INTO IOWA/MINNESOTA WEDNESDAY AFTERNOON WITH SOME WEAK INSTABILITY DEVELOPING IN THE AFTERNOON. WINDS WILL BECOME NORTH WEDNESDAY AFTERNOON AS THE SFC LOW EXITS NORTHERN ILLINOIS BY EARLY WEDNESDAY EVENING. MARSILI && .MARINE... 316 PM CDT LOW PRESSURE ON THE MISSOURI-IOWA BORDER WILL MOVE SLOWLY INTO FAR NORTHERN ILLINOIS TONIGHT THEN TO SOUTHERN LOWER MICHIGAN DURING WEDNESDAY. AS A LOW MOVES ACROSS NORTHERN ONTARIO THURSDAY A TRAILING COLD FRONT WILL DROP THROUGH THE GREAT LAKES. HIGH PRESSURE BUILDS SOUTH FROM CENTRAL CANADA INTO THE NORTHERN PLAINS FRIDAY...THEN SETTLES OVER THE GREAT LAKES SATURDAY. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. &&
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
341 PM CDT TUE MAY 26 2009
ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
272045-
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-
341 PM CDT TUE MAY 26 2009 /441 PM EDT TUE MAY 26 2009/
THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
.DAY ONE...TONIGHT.
WEATHER HAZARDS EXPECTED:
SCATTERED THUNDERSTORMS...SOME OF WHICH MAY PRODUCE:
LOCALLY HEAVY DOWNPOURS.
CLOUD TO GROUND LIGHTNING.
AREAS AFFECTED AND TIMING:
SCATTERED THUNDERSTORMS WILL AFFECT MUCH OF THE OUTLOOK AREA
THROUGH MID EVENING...BEFORE DIMINISHING IN COVERAGE WITH THE
LOSS OF INSTABILITY AROUND SUNSET. THUNDERSTORMS WILL BE MOST
COMMON ALONG AND SOUTH OF THE INTERSTATE 80 CORRIDOR...ALONG
AND SOUTH OF A WARM FRONT. THUNDERSTORMS WILL BECOME MORE
ISOLATED OVERNIGHT.
DISCUSSION:
LOW PRESSURE ALONG THE IOWA MISSOURI BORDER WILL MOVE NORTHEAST
INTO NORTHERN ILLINOIS OVERNIGHT...WITH A WARM FRONT LIFTING
ACROSS LAKE MICHIGAN AND THE LOWER MICHIGAN PENINSULA. WARM
HUMID AND UNSTABLE AIR ALONG AND SOUTH OF THE WARM FRONT WILL
RESULT IN SCATTERED THUNDERSTORMS INTO THIS EVENING...BEFORE
DIMINISHING IN COVERAGE WITH THE LOSS OF INSTABILITY AFTER
SUNSET. THUNDERSTORMS WILL BECOME MORE ISOLATED DURING THE
OVERNIGHT HOURS. SLOW STORM MOVEMENT AND A VERY MOIST AIRMASS
MAY RESULT IN LOCALLY HEAVY RAINFALL WITH THESE STORMS...WITH
LOCALIZED RAINFALL AMOUNTS IN EXCESS OF AN INCH POSSIBLE.
PORTIONS OF THE ILLINOIS RIVER WILL REMAIN IN FLOOD.
.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
THERE IS CHANCE OF THUNDERSTORMS WEDNESDAY.
PORTIONS OF THE ILLINOIS RIVER WILL REMAIN IN FLOOD THROUGH
FRIDAY EVENING.
THERE IS ANOTHER CHANCE OF THUNDERSTORMS SATURDAY INTO TUESDAY.
.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>745-272045-
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-
341 PM CDT TUE MAY 26 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS NEARSHORE
WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE WATERS OF LAKE
MICHIGAN.
.DAY ONE...TONIGHT.
ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE TONIGHT.
.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY.
THERE IS ANOTHER CHANCE OF THUNDERSTORMS SUNDAY NIGHT.
&&
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-
870-872-874-876-878-272045-
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-
341 PM CDT TUE MAY 26 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE
MICHIGAN.
.DAY ONE...TONIGHT.
THERE IS A CHANCE OF THUNDERSTORMS ACROSS SOUTHERN LAKE MICHIGAN
TONIGHT.
.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY...AND AGAIN
THERE WILL BE ANOTHER CHANCE OF THUNDERSTORMS SATURDAY THROUGH
TUESDAY.
&&
COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO
RATZERThe national radar mosaic for the moment the first event began.
3 flood. Local standard time, as filed.
Five inches of flowing water was reported on County Line Road between Holt Road and US 52.
One foot of water was reported covering part of Route 126 just north of downtown Plainfield. Three inches of flowing water was reported on Route 53 between 83rd and Boughton Road in Bolingbrook.
Five inches of standing water was reported in the 7700 block of Cicero Avenue.
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, May 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: 166598, 166599, 166600.