Hail and Damaging Winds in Illinois, July 20 to 21, 2003

Name: Hail and Damaging Winds in Illinois, July 20 to 21, 2003
Start: 2003-07-20T16:50
End: 2003-07-21T02:03
Location: Illinois

July 20 to 21, 2003 · NWS LOT · 21 events in 11 counties and zones

Where it happened

Every event with a place to put it; 1 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: $25,000
Crop damage: None recorded
Events: 21

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.

Thunderstorms developed during the evening hours of July 20th across parts of northern Illinois and continued into the early morning hours of July 21st. Winds gusted to 60 to 65 mph across parts of Cook county. An estimated 300 to 400 tress were damaged or blown down in Evergreen Park. One of the trees fell onto a house in Evergreen Park. An estimated 50 mature trees were blown down in Naperville. One of the trees destroyed a backyard playhouse. A gust to 60 mph was reported in Woodridge in Dupage county, which blew down some tree limbs. By late evening, thunderstorms redeveloped over parts of northern Illinois producing severe hail. The largest hail reported was golf ball size hail in Kankakee. A building suffered roof and structural damage in Ashton in Lee county from winds as high as 75 mph. Trees were blown down southwest of Polo in Ogle county along Illinois Route 26. A gust to 64 mph was reported in Sandwich in Dekalb county. A tree fell onto a house in Mt. Prospect causing some roof damage and lightning hit a mobile home in Elk Grove Village, which blew out the home's wiring and started a fire. Trees, large tree limbs and power lines were blown down in Sheridan in La Salle county. Trees and large limbs were blown down in Melvin in Ford county and windows were blown out of some buildings in Melvin. Two trees were blown down in New Lenox in Will county where a woman was trapped in her car, but not injured. Trees and large tree limbs were blown down in Fairbury in Livingston county. Minor flooding was reported in Joliet in Will county.

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 Jul 20, 2:15 PM CST, 2 hours 35 minutes earlier.

Area forecast discussion, Jul 20, 2:15 PM CST, 2 hours 35 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
315 PM CDT SUN JUL 20 2003

PUBLIC DISCUSSION AFTERNOON ZONES/GRIDS:

MAIN PROBLEM THIS EVENING IS WITH TSTM FCST.  SPC HAS LOWERED REGION
INTO SLIGHT RISK AS LO LEVEL FEATURES ARE AS YET POORLY DEFINED. SFC
DEW POINTS HAVE RISEN INTO LOER 70S BUT MOISTURE CONVERGENCE REMAINS
QUITE NEBULOUS ACROSS MOST OF MIDWEST.  CONVECTIVE DEBRIS HAS
CONTRIBUTED TO RELATIVE STABILIZATION COMPARED TO AREAS TO OUR W AND
S WHERE LIFTED INDEX VALUES ARE NOW RUNNING AOB -10.  BASED ON
THIS...BELIEVE DYNAMIC FORCING WILL BE REQUIRED TO GENERATE
CONVECTION.  VIGOROUS, DIGGING S/W TROF NOW ROTG SSEWD ACROSS WRN
ONTARIO WITH VORT TAIL ARCING SWWD INTO ND ATTM BASED ON AFTN SATLT
LOOPS.  EXPECT THIS TO TRIGGER MORE ORGANIZED CONVECTION NXT FEW HRS
WELL TO OUR NW WITH THESE STORMS MAINTAINING THEMSELVES OVERNIGHT
DUE TO MORE FAVORABLE DYNAMICS.  AS A RESULT WILL KEEP LIKELY POPS
GOING IN FCST BUT WILL MENTION THIS AS AN OVERNIGHT EVENT.  THIS IS
ALSO SUPPORTED BY MOS AND ALL MODELS CONCUR IN BRINGING OMEGA MAX
ACROSS FA OVERNIGHT.  SOME PRECIP WILL LIKELY LINGER INTO MONDAY
MORNING.  REMAINDER OF FCST CHANGED LTL FROM GUID WITH ETA AND GFS
IN FAIRLY GOOD AGREEMENT ON STRENGTH OF COLD AVDECTION THRU ERLY
PART OF UPCOMING WEEK.   WILL KEEP MOSTLY CLOUDY CONDS AT LEAST THRU
MONDAY DUE TO SHARP CYCLONINC TURNING IN MID/UPR LVL FLOW AND ASSD
COLD ADVECTION.  SKIES SHOULD CLEAR TUES NIGHT AS H5 TROF AXIS
SHIFTS EWD AND SFC HI PRES BUILDS SEWD INTO FA.

.CHI...NONE
MERZLOCK

Hazardous weather outlook, Jul 20, 3:20 PM CST, 1 hour 30 minutes before

ILZ003>006-008-010>014-019-020>023-032-033-039-INZ001-002-010-011-019
-2011200-

HAZARDOUS WEATHER OUTLOOK/UPDATED
NATIONAL WEATHER SERVICE CHICAGO IL
420 PM CDT SUN JUL 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL AND NORTHEAST
ILLINOIS...NORTHWEST INDIANA...AND THE ADJACENT WATERS OF LAKE
MICHIGAN.

.DAY ONE...TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT OVER NORTHERN
ILLINOIS AND NORTHWEST INDIANA.

A VERY UNSTABLE AIRMASS LATE THIS AFTERNOON OVER THE AREA AND A WEAK
SURFACE BOUNDARY WILL LEAD TO THE POTENTIAL OF SEVERE THUNDERSTORMS.
THE GREATEST THREAT WILL BE STRONG DAMAGING WINDS AND LARGE HAIL.

SCATTERED STORMS ARE EXPECTED OVER NORTHERN ILLINOIS INTO NORTHWEST
INDIANA THROUGH 10 PM. SOME OF THESE MAY BE SEVERE. AFTER 10 PM A
STRONG LINE OF STORMS IS EXPECTED TO MOVE RAPIDLY SOUTHEAST FROM
MINNESOTA AND SWEEP OVER THE AREA BETWEEN 10 PM AND 3 AM. THIS LINE
WILL BE WITH A SOUTHWARD MOVING COLD FRONT NOW BACK IN CENTRAL
MINNESOTA.

.DAYS TWO THROUGH SEVEN... MONDAY THROUGH SUNDAY

THERE IS A CHANCE OF LINGERING SHOWERS AND THUNDERSTORMS EARLY
MONDAY. THESE THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE.  THE NEXT
CHANCE OF THUNDERSTORMS WILL BE ABOUT SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE REQUIRED THIS EVENING AND TONIGHT.
.

&&

           NWS CHICAGO WEBPAGE

    HTTP://WWW.CRH.NOAA.GOV/LOT (LOWER CASE)
OR  HTTP://WEATHER.NOAA.GOV/CHICAGO (LOWER CASE)

AF

The radar

The Quad Cities radar (KDVN), 105 km away, was scanning. The volume nearest the first event began at 22:48 UTC.

Open the radar archive at this moment

Event by event

12 thunderstorm wind, 8 hail, 1 lightning. Local standard time, as filed.

Hail, Lee

When: July 20, 4:50 PM CST to 5:05 PM CST
Where: Lee County, 3 mi N of Amboy
Measured: 0.88 in hail
Reported by: GOVT OFFICIAL
Coordinates: 41.767, -89.333

Thunderstorm Wind, Cook

When: July 20, 5:04 PM CST
Where: Cook County, Burbank
Measured: 52 kt (60 mph) estimated gust
Reported by: TRAINED SPOTTER
Coordinates: 41.733, -87.767

Thunderstorm Wind, Cook

When: July 20, 5:08 PM CST
Where: Cook County, Hometown
Measured: 52 kt (60 mph) estimated gust
Reported by: TRAINED SPOTTER
Coordinates: 41.733, -87.733

Thunderstorm Wind, Du Page

When: July 20, 5:10 PM CST to 5:15 PM CST
Where: Du Page County, Naperville
Measured: 52 kt (60 mph) estimated gust
Reported by: LAW ENFORCEMENT
Coordinates: 41.783, -88.150

Thunderstorm Wind, Cook

When: July 20, 5:12 PM CST
Where: Cook County, Evergreen Park
Measured: 57 kt (66 mph) estimated gust
Reported by: BROADCAST MEDIA
Coordinates: 41.717, -87.667

Hail, Lake

When: July 20, 9:15 PM CST to 9:20 PM CST
Where: Lake County, Long Grove
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 42.183, -88.000

Hail, Kankakee

When: July 20, 9:34 PM CST to 9:39 PM CST
Where: Kankakee County, Kankakee
Measured: 1.75 in hail
Reported by: GENERAL PUBLIC
Coordinates: 41.117, -87.850

Hail, Cook

When: July 20, 9:50 PM CST to 9:55 PM CST
Where: Cook County, Palatine
Measured: 1 in hail
Reported by: EMERGENCY MANAGER
Coordinates: 42.100, -88.050

Hail, Cook

When: July 20, 9:52 PM CST to 9:57 PM CST
Where: Cook County, Arlington Hgts
Measured: 0.75 in hail
Reported by: NWS EMPLOYEE(OFF DUTY)
Coordinates: 42.083, -88.000

Hail, Cook

When: July 20, 9:52 PM CST to 9:57 PM CST
Where: Cook County, Des Plaines
Measured: 0.75 in hail
Reported by: GENERAL PUBLIC
Coordinates: 42.033, -87.900

Thunderstorm Wind, Cook

When: July 20, 10:00 PM CST
Where: Cook County, Mt Prospect
Measured: 57 kt (66 mph) estimated gust
Reported by: NEWSPAPER
Coordinates: 42.067, -87.933

Lightning, Cook

When: July 20, 10:00 PM CST
Where: Cook County, Elk Grove Vlg
Property damage: $25,000
Reported by: NEWSPAPER
Coordinates: 41.895, -87.646 (the zone’s center; the record gives no point)

Hail, Cook

When: July 20, 10:05 PM CST to 10:15 PM CST
Where: Cook County, Lincolnwood
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 42.017, -87.733

Penny size hail was reported along Lincoln Avenue and lasted 10 minutes.

Hail, Cook

When: July 20, 11:50 PM CST
Where: Cook County, Lansing
Measured: 1 in hail
Reported by: GENERAL PUBLIC
Coordinates: 41.567, -87.550

Thunderstorm Wind, Lee

When: July 21, 12:22 AM CST to 12:30 AM CST
Where: Lee County, Ashton
Measured: 65 kt (75 mph) estimated gust
Reported by: GOVT OFFICIAL
Coordinates: 41.867, -89.217

Thunderstorm Wind, Ogle

When: July 21, 12:35 AM CST
Where: Ogle County, Polo
Measured: 52 kt (60 mph) estimated gust
Reported by: LAW ENFORCEMENT
Coordinates: 41.983, -89.583

Thunderstorm Wind, De Kalb

When: July 21, 1:14 AM CST
Where: De Kalb County, Sandwich
Measured: 56 kt (64 mph) estimated gust
Reported by: AMATEUR RADIO
Coordinates: 41.650, -88.617

Thunderstorm Wind, La Salle

When: July 21, 1:40 AM CST
Where: La Salle County, Sheridan
Measured: 57 kt (66 mph) estimated gust
Reported by: LAW ENFORCEMENT
Coordinates: 41.533, -88.683

Thunderstorm Wind, Livingston

When: July 21, 1:40 AM CST
Where: Livingston County, Fairbury
Measured: 57 kt (66 mph) estimated gust
Reported by: NEWSPAPER
Coordinates: 40.750, -88.517

Thunderstorm Wind, Ford

When: July 21, 1:50 AM CST
Where: Ford County, Melvin
Measured: 52 kt (60 mph) estimated gust
Reported by: DEPT OF HIGHWAYS
Coordinates: 40.567, -88.233

Thunderstorm Wind, Will

When: July 21, 2:03 AM CST
Where: Will County, New Lenox
Measured: 52 kt (60 mph) estimated gust
Reported by: EMERGENCY MANAGER
Coordinates: 41.517, -87.967

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.
Lightning: A lightning strike that killed, injured or caused damage.

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

The same day elsewhere

Every storm in Illinois in 2003 Every state in 2003 This day in weather history Warnings in Illinois, July 2003

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: 5373626, 5373610, 5373611, 5373613, 5373612, 5373614, 5373615, 5373616, 5373617, 5373618, 5373628, 5373629, 5373619, 5373620, 5373621, 5373630, 5373622, 5373623, 5373627, 5373624, 5373625.