Alert archive / Illinois / Flash Flood Warnings in 2025

Flash Flood Warning 2, NWS Chicago, IL

June 18, 2025Cook County, DuPage County, Illinois

NWS Chicago, IL issued this flash flood warning at Jun 18, 2025, 6:50 PM CDT for Cook County, DuPage County, Illinois. It was in force for 100 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jun 18, 2025, 6:50 PM CDT (23:50 UTC)
Expired: Jun 18, 2025, 8:30 PM CDT
In force: 100 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties Cook County, IL, DuPage County, IL

The radar

The Chicago radar (KLOT), 35 km from the middle of the area, began a volume at 23:49 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 12:00Z, 11.8 hours before the alert went out and 201 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: 550 J/kg
Mixed-layer CIN: -132 J/kg
Mixed-layer LCL: 960 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 124 m²/s²
0-3 km storm-relative helicity: 110 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

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 Jun 18, 6:33 PM CDT, 17 minutes earlier.

Area forecast discussion, Jun 18, 6:33 PM CDT, 17 minutes before

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Hazardous weather outlook, Jun 18, 4:16 PM CDT, 2 hours 34 minutes before

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In the hours before

Local storm report, Jun 18, 5:41 PM CDT, 1 hour 9 minutes before

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Local storm report, Jun 18, 6:03 PM CDT, 47 minutes before

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Local storm report, Jun 18, 6:08 PM CDT, 42 minutes before

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Local storm report, Jun 18, 6:10 PM CDT, 40 minutes before

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Local storm report, Jun 18, 6:12 PM CDT, 38 minutes before

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Local storm report, Jun 18, 6:16 PM CDT, 34 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
Jun 17, 7:51 PM CDT	Special Weather Statement	LOT	Grundy	24 min
Jun 17, 10:01 PM CDT	Special Weather Statement	LOT	Grundy	29 min
Jun 18, 10:28 AM CDT	Flood Watch	LOT	Cook, DuPage, Grundy, Kankakee, Kendall, LaSalle and 2 more	11 hr
Jun 18, 1:06 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	54 min
Jun 18, 1:23 PM CDT	Areal Flood Advisory	LOT	Ford, Iroquois, Kankakee, Livingston	3 hr
Jun 18, 1:45 PM CDT	Flash Flood Warning	LOT	Iroquois, Kankakee	2 hr
Jun 18, 1:57 PM CDT	Severe Thunderstorm Warning	LOT	Kankakee	63 min
Jun 18, 2:44 PM CDT	Special Marine Warning	LOT		61 min
Jun 18, 3:52 PM CDT	Special Weather Statement	LOT	Ogle	68 min
Jun 18, 3:52 PM CDT	Special Weather Statement	LOT	Ogle	68 min
Jun 18, 4:55 PM CDT	Areal Flood Advisory	LOT	Boone, Ogle, Winnebago	3 hr
Jun 18, 4:56 PM CDT	Special Weather Statement	LOT	McHenry	34 min
Jun 18, 5:07 PM CDT	Areal Flood Advisory	LOT	Cook, Will	3 hr
Jun 18, 5:33 PM CDT	Areal Flood Advisory	LOT	Boone, DeKalb, Lee, McHenry, Ogle	3 hr
Jun 18, 5:39 PM CDT	Special Weather Statement	LOT	Lee, McHenry	51 min
Jun 18, 6:22 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage	3 hr
Jun 18, 1:36 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Benton, Jasper, Newton	54 min

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.