Alert archive / Illinois / Flash Flood Warnings in 2019

Flash Flood Warning 15, NWS Chicago, IL

July 21, 20194 counties in Illinois

NWS Chicago, IL issued this flash flood warning at Jul 21, 2019, 10:39 AM CDT for 4 counties in 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 21, 2019, 10:39 AM CDT (15:39 UTC)
Expired: Jul 21, 2019, 1:45 PM CDT
In force: 3 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties DeKalb County, IL, Kane County, IL, Kendall County, IL, LaSalle County, IL

The radar

The Chicago radar (KLOT), 46 km from the middle of the area, began a volume at 15:40 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, 3.7 hours before the alert went out and 171 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: 53 J/kg
Mixed-layer CIN: -241 J/kg
Mixed-layer LCL: 1780 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: -93 m²/s²
0-3 km storm-relative helicity: -54 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 21, 6:51 AM CDT, 3 hours 48 minutes earlier.

Area forecast discussion, Jul 21, 6:51 AM CDT, 3 hours 48 minutes before

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Hazardous weather outlook, Jul 21, 6:58 AM CDT, 3 hours 41 minutes before

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In the hours before

Local storm report, Jul 21, 10:08 AM CDT, 31 minutes before

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Local storm report, Jul 21, 10:25 AM CDT, 14 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 21, 4:15 AM CDT	Small Craft Advisory	LOT		47 hr
Jul 21, 4:17 AM CDT	Beach Hazards Statement	LOT	Lake	49 hr
Jul 21, 4:35 AM CDT	Areal Flood Advisory	LOT	Cook, Lake	3 hr
Jul 21, 9:33 AM CDT	River Flood Advisory	LOT	Cook	8 hr
Jul 21, 9:33 AM CDT	River Flood Advisory	LOT	Cook	11 hr
Jul 21, 10:12 AM CDT	Areal Flood Advisory	LOT	DuPage, Kane, Kendall	3 hr
Jul 21, 10:15 AM CDT	Areal Flood Advisory	LOT	DeKalb, LaSalle	3 hr
Jul 21, 11:58 AM CDT	Areal Flood Advisory	LOT	LaSalle	3 hr
Jul 21, 12:21 PM CDT	Special Weather Statement	LOT	Kankakee	24 min
Jul 21, 12:31 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Will	3 hr
Jul 21, 12:45 PM CDT	Special Weather Statement	LOT	Kankakee	15 min
Jul 21, 12:51 PM CDT	Flash Flood Warning	LOT	Grundy, Kankakee, Will	3 hr
Jul 21, 1:08 PM CDT	Special Weather Statement	LOT	Kankakee	37 min
Jul 21, 1:30 PM CDT	Special Weather Statement	LOT	Iroquois	30 min
Jul 21, 5:04 PM CDT	River Flood Warning	LOT	Cook	17 hr
Jul 21, 1:53 PM CDT	Special Weather Statement	LOT	Newton	37 min
Jul 21, 2:12 PM CDT	Severe Thunderstorm Warning	LOT	Jasper, Lake, Newton, Porter	63 min
Jul 21, 2:29 PM CDT	Special Weather Statement	LOT	Benton	31 min

Nearby

Flash Flood Warnings in Illinois, 2019 Every flash flood warning in 2019

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.