Alert archive / Illinois / Flash Flood Warnings in 2023

Flash Flood Warning 9, NWS Chicago, IL

July 12, 2023Cook County, DuPage County, Will County, Illinois

NWS Chicago, IL issued this flash flood warning at Jul 12, 2023, 1:20 PM CDT for Cook County, DuPage County, Will 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 12, 2023, 1:20 PM CDT (18:20 UTC)
Expired: Jul 12, 2023, 4:30 PM CDT
In force: 3 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties Cook County, IL, DuPage County, IL, Will County, IL

The radar

The Chicago radar (KLOT), 21 km from the middle of the area, began a volume at 18:21 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

Davenport, (KDVN), launched 12:00Z, 6.3 hours before the alert went out and 216 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: 9 J/kg
Mixed-layer CIN: -301 J/kg
Mixed-layer LCL: 936 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 48 m²/s²
0-3 km storm-relative helicity: 252 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

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 12, 12:57 PM CDT, 23 minutes earlier.

Area forecast discussion, Jul 12, 12:57 PM CDT, 23 minutes before

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Hazardous weather outlook, Jul 12, 12:13 PM CDT, 1 hour 7 minutes before

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In the hours before

Special weather statement, Jul 12, 11:42 AM CDT, 1 hour 38 minutes before

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Special weather statement, Jul 12, 12:05 PM CDT, 1 hour 15 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 12, 3:49 AM CDT	Flood Watch	LOT	Cook, DuPage, Will	15 hr
Jul 12, 4:24 AM CDT	Areal Flood Advisory	LOT	Cook, DeKalb, Kendall, Will	3 hr
Jul 12, 10:42 AM CDT	River Flood Warning	LOT	Cook	20 hr
Jul 12, 11:42 AM CDT	Special Weather Statement	LOT	Putnam	63 min
Jul 12, 12:05 PM CDT	Special Weather Statement	LOT	LaSalle	40 min
Jul 12, 5:37 PM CDT	Tornado Warning	LOT	DuPage, Kane, Kendall, Will	23 min
Jul 12, 6:10 PM CDT	Tornado Warning	LOT	Cook	20 min
Jul 12, 6:13 PM CDT	Tornado Warning	LOT	McHenry	32 min
Jul 12, 6:18 PM CDT	Tornado Warning	LOT	Kane	27 min
Jul 12, 6:20 PM CDT	Tornado Warning Tornado observedConsiderable damage threat	LOT	Cook	23 min
Jul 12, 6:22 PM CDT	Special Marine Warning	LOT		113 min
Jul 12, 6:31 PM CDT	Tornado Warning	LOT	Cook, DuPage	29 min
Jul 12, 6:35 PM CDT	Tornado Warning	LOT	Lake	25 min
Jul 12, 6:51 PM CDT	Tornado Warning	LOT	Cook, DuPage	24 min

Nearby

Flash Flood Warnings in Illinois, 2023 Every flash flood warning in 2023

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.