Flooding and Hail in Illinois, October 24, 2001

Name: Flooding and Hail in Illinois, October 24, 2001
Start: 2001-10-24T08:05
End: 2001-10-24T15:30
Location: Illinois

October 24, 2001 · NWS LOT · 11 events in 9 counties and zones

Where it happened

Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 11

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.

What happened

The episode as NWS LOT wrote it up.

Isolated severe thunderstorms developed across northern Illinois during the morning of October 24th ahead of a strong cold front. As the cold front moved east into northern Illinois, the thunderstorms formed a squall line and began to produce widespread wind damage across northeast and eastern Illinois. During the morning, thunderstorms produced nickel size hail in Cook county, quarter size hail in Dekalb county and nickle size hail in McHenry and Kane counties.As the thunderstorms formed into a squall line, a tree was blown down in Pontiac in Livingston county. In Ford county, a utility pole was blown down in Elliott, part of a roof was blown off a house in Paxton, and a barn was blown down killing a horse near Melvin. In Kankakee county, trees and power lines were reported down across the entire county. In Bourbonnais in Kankakee county, a roof was blown off a bakery and a wall at a construction site was blown over. A wind gust of 60 mph was recorded in Bonfield. In Will county, trees and power lines were blown down in Crete and a semi was overturned in Petone. In Cook county, trees and power lines were blown down across the southern part of the county. Windows were broken at three businesses in Chicago Heights. In addition to the wind damage, many reports of minor street flooding were reported across Dupage and Cook counties.For Marine reports, see StormData October 2001, Lake Michigan.

What forecasters said that day

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 Oct 24, 1:45 AM CST, 6 hours 20 minutes earlier.

Area forecast discussion, Oct 24, 1:45 AM CST, 6 hours 20 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
245 AM CDT WED OCT 24 2001

TIME TO BATTEN DOWN THE HATCHES.

SEVERE BOW ECHO THAT RAN THROUGH FAR NRN IL NOW WELL ACROSS THE
LAKE. FRONTAL DISCONTINUITY EVIDENT...AS TEMPS SHIFT FROM LOWER 60S
HERE TO LOWER 50S OVER SRN WISCONSIN.

EXTREMELY DYNAMIC SYSTEM TO AFFECT THE REGION THROUGH THE NEAR TERM
OF THE FORECAST. MODEL FORECAST WIND FIELDS STRONGER THAN PROJECTED
LAST NIGHT. NRN ILLINOIS IN THE LEFT FRONT QUAD OF APPROACHING 130+
KNOT 2H JET...PROVIDING ADDITIONAL SUPPORT FOR POWERFUL MIDLEVEL
JET PUNCHING INTO THE AREA. EXPECT SQUALL LINE TO FORM TO OUR WEST
THIS AM AND ROLL THROUGH THE AREA BY EARLY AFTERNOON. DAMAGING
WINDS ARE LIKELY WITH THIS SQUALL LINE...ESPECIALLY XTRM SE
SXNS...WHICH SPC HAS IN A HIGH RISK AREA.

MODELS ARE CONSISTENT TO A DEGREE IN VERY RAPIDLY DEEPENING SFC
LOW...TO THE EXTENT OF A 970MB SURFACE LOW BY EARLY AFTERNOON
THURSDAY. STORM WARNINGS ARE ALREADY POSTED FOR LAKE MICHIGAN...AND
SOME SORT OF WIND ADVISORY/HIGH WIND WARNING WILL LIKELY BE NEEDED
FOR THE DAYLIGHT HOURS TOMORROW.

COLD AIR COMING IN BEHIND THE FRONT WILL SHARPLY DROP TEMPERATURES
THIS AFTERNOON...WITH COLD AIR BECOMING ENTRENCHED FROM TONIGHT
THROUGH AT LEAST FRIDAY. CONDITIONS TO REMAIN BLUSTERY RIGHT ON
INTO THE WEEKEND BEFORE SOME MODERATION AS UPPER LOW MOVES EAST OF
THE AREA.

.CHI...STORM WARNING LKMICH.

JHV

In the hours before

Local storm report, Oct 24, 2:50 AM CST, 5 hours 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
350 AM CDT WED OCT 24 2001

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1110 PM    LAKE SUMMERSET                 IL   QUARTER SIZE HAIL
10/23/01   WINNEBAGO

1115 PM    3 N OF PECATONICA              IL   QUARTER TO HALF DOLLAR
10/23/01   WINNEBAGO                           SIZE HAIL

1143 PM    ROCKFORD                       IL   DIME SIZE HAIL
10/23/01   WINNEBAGO

1208 AM    1 N BELVIDERE                  IL   QUARTER SIZED HAIL
10/24/01   BOONE

1258 AM    INGLESIDE                      IL   3/4 INCH HAIL
10/24/01   LAKE

104  AM    GRAYS LAKE                     IL   3/4 INCH HAIL
10/24/01   LAKE                                COVERING THE GROUND

PAUL MERZLOCK
WFO CHICAGO

Special weather statement, Oct 24, 5:05 AM CST, 3 hours before

ILZ003>006-008-010>014-019>023-032>033-039-INZ001>002-010>011-019-
251100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
600 AM CDT/EST WED OCT 24 2001

FOR NORTH CENTRAL AND NORTHEAST ILLINOIS AND NORTHWEST INDIANA...

THERE IS A SLIGHT RISK OF DAMAGING WINDS AND LARGE HAIL OVER THE
OUTLOOK AREA TODAY. ADDITIONALLY...THERE IS A HIGHER RISK OF
DAMAGING WINDS OVER FAR SOUTHEAST PORTIONS OF THE OUTLOOK
AREA...GENERALLY SOUTHEAST OF A LINE FROM VALPARAISO TO PIPER CITY.

A STRONG UPPER LEVEL DISTURBANCE WILL BE A FOCUS FOR CONVECTION
BREAKING OUT TODAY. THE CONVECTION IS EXPECTED TO ORGANIZE INTO ONE
OR MORE SQUALL LINES...EACH CAPABLE OF PRODUCING SEVERE WIND GUSTS
AND LARGE HAIL. THIS RISK IS HIGHER OVER FAR SOUTHEAST PORTIONS OF
THE OUTLOOK AREA WHERE MOISTURE AND INSTABILITY ARE MAXIMIZED.

IN ADDITION...STRONG NON-THUNDERSTORM WINDS WILL BEGIN TONIGHT AS
COLD AIR RUSHES INTO THE REGION. ALTHOUGH THE STRONGEST WINDS WILL
HOLD OFF UNTIL THURSDAY...CAUTION IS ADVISED BEGINNING LATE TONIGHT.

JHV

The radar

The Chicago radar (KLOT), 44 km away, was scanning. The volume nearest the first event began at 14:05 UTC.

Open the radar archive at this moment

Event by event

5 thunderstorm wind, 4 hail, 2 flood. Local standard time, as filed.

Hail, Cook

When: October 24, 8:05 AM CST to 8:13 AM CST
Where: Cook County, Chicago
Measured: 0.88 in hail
Reported by: TRAINED SPOTTER
Coordinates: 41.833, -87.650

Hail, De Kalb

When: October 24, 10:00 AM CST
Where: De Kalb County, De Kalb
Measured: 1 in hail
Reported by: TRAINED SPOTTER
Coordinates: 41.933, -88.750

Hail, Kane

When: October 24, 10:40 AM CST
Where: Kane County, Algonquin
Measured: 0.88 in hail
Reported by: TRAINED SPOTTER
Coordinates: 42.167, -88.283

Hail, McHenry

When: October 24, 10:43 AM CST
Where: McHenry County, Algonquin
Measured: 0.88 in hail
Reported by: TRAINED SPOTTER
Coordinates: 42.167, -88.283

Thunderstorm Wind, Livingston

When: October 24, 12:38 PM CST
Where: Livingston County, Pontiac
Measured: 50 kt (58 mph)
Reported by: LAW ENFORCEMENT
Coordinates: 40.867, -88.617

Thunderstorm Wind, Ford

When: October 24, 12:40 PM CST to 12:55 PM CST
Where: Ford County, Elliott
Measured: 55 kt (63 mph)
Reported by: LAW ENFORCEMENT
Coordinates: 40.467, -88.267

Thunderstorm Wind, Kankakee

When: October 24, 1:22 PM CST to 1:40 PM CST
Where: Kankakee County, Countywide
Measured: 55 kt (63 mph)
Reported by: LAW ENFORCEMENT
Coordinates: 41.150, -87.900

Flood, Cook

When: October 24, 1:30 PM CST to 3:30 PM CST
Where: Cook County, Countywide
Reported by: LAW ENFORCEMENT
Coordinates: 41.895, -87.646 (the zone’s center; the record gives no point)

Flood, Du Page

When: October 24, 1:30 PM CST to 3:30 PM CST
Where: Du Page County, Countywide
Reported by: LAW ENFORCEMENT
Coordinates: 41.852, -88.086 (the zone’s center; the record gives no point)

Thunderstorm Wind, Cook

When: October 24, 1:33 PM CST to 1:40 PM CST
Where: Cook County, Chicago Hgts
Measured: 50 kt (58 mph)
Reported by: NEWSPAPER
Coordinates: 41.500, -87.633

Thunderstorm Wind, Will

When: October 24, 1:45 PM CST to 1:50 PM CST
Where: Will County, Crete
Measured: 50 kt (58 mph)
Reported by: LAW ENFORCEMENT
Coordinates: 41.450, -87.633

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Illinois in 2001 Every state in 2001 This day in weather history Warnings in Illinois, October 2001

Sources

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: 5270839, 5270842, 5270840, 5270841, 5270843, 5270844, 5270845, 5270848, 5270849, 5270846, 5270847.