Alert archive / Illinois / Flash Flood Warnings in 2025

Flash Flood Warning 4, NWS Chicago, IL

July 8, 2025Cook County, Illinois

NWS Chicago, IL issued this flash flood warning at Jul 8, 2025, 9:45 PM CDT for Cook County, Illinois. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 8, 2025, 9:45 PM CDT (02:45 UTC)
Expired: Jul 9, 2025, 12:45 AM CDT
In force: 3 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

County Cook County, IL

The radar

The Chicago radar (KLOT), 49 km from the middle of the area, began a volume at 02:45 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 2.8 hours before the alert went out and 210 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 406 J/kg
Mixed-layer CIN: -56 J/kg
Mixed-layer LCL: 879 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -46 m²/s²
0-3 km storm-relative helicity: -8 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, 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 this flash flood warning went out at Jul 8, 8:59 PM CDT, 46 minutes earlier.

Area forecast discussion, Jul 8, 8:59 PM CDT, 46 minutes before

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Hazardous weather outlook, Jul 8, 8:31 PM CDT, 1 hour 14 minutes before

Hazardous Weather Outlook...UPDATED
National Weather Service Chicago/Romeoville IL
831 PM CDT Tue Jul 8 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-100145-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
831 PM CDT Tue Jul 8 2025 /931 PM EDT Tue Jul 8 2025/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk.
  Limited Flooding Risk.

DISCUSSION...

Lingering showers and isolated thunderstorms, mainly focused
near and south of the I-80 corridor, will gradually diminish in
coverage from west to east across the area during the late evening
and overnight hours. The threat for damaging winds has diminished
with sunset, with the threat of flooding also diminishing this
evening.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday and Thursday...
  Hazardous swimming conditions possible at Lake Michigan beaches.
  Limited Thunderstorm Risk.
Friday...
  Elevated Thunderstorm Risk.
  Limited Flooding Risk.
Saturday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east-northeast at around 15 mph.

LMZ740>745-100145-
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 to Burns Harbor IN-
Burns Harbor to Michigan City IN-
831 PM CDT Tue Jul 8 2025

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Wednesday through Saturday...
  Limited Thunderstorm Risk at times.

Ratzer

Visit us at www.weather.gov/chicago

In the hours before

Local storm report, Jul 8, 4:15 PM CDT, 5 hours 30 minutes before

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Local storm report, Jul 8, 4:47 PM CDT, 4 hours 58 minutes before

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Local storm report, Jul 8, 4:48 PM CDT, 4 hours 57 minutes before

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Local storm report, Jul 8, 4:49 PM CDT, 4 hours 56 minutes before

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Local storm report, Jul 8, 5:15 PM CDT, 4 hours 30 minutes before

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Special weather statement, Jul 8, 6:35 PM CDT, 3 hours 10 minutes before

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The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 8, 7:27 PM CDT	Areal Flood Advisory	LOT	LaSalle	2 hr
Jul 8, 9:30 PM CDT	Areal Flood Advisory	LOT	Cook	2 hr
Jul 8, 10:22 PM CDT	Areal Flood Advisory	LOT	Cook	83 min
Jul 8, 11:43 PM CDT	Areal Flood Advisory	LOT	Cook	3 hr
Jul 9, 12:45 AM CDT	Areal Flood Advisory	LOT	Cook	4 hr
Jul 9, 2:55 AM CDT	Beach Hazards Statement	LOT	Cook, Lake	31 hr
Jul 9, 3:46 AM CDT	Dense Fog Advisory	LOT	Boone, DeKalb, Grundy, Kane, Kendall, LaSalle and 5 more	5 hr

Nearby

Flash Flood Warnings in Illinois, 2025 Every flash flood warning in 2025

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.