Alert archive / Illinois / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 33, NWS Chicago, IL

March 20, 2017Ford County, Iroquois County, Livingston County, Illinois; Benton County, Newton County, Indiana

NWS Chicago, IL issued this severe thunderstorm warning at Mar 20, 2017, 11:27 AM CDT for Ford County, Iroquois County, Livingston County, Illinois; Benton County, Newton County, Indiana. It was in force for 48 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: Mar 20, 2017, 11:27 AM CDT (16:27 UTC)
Expired: Mar 20, 2017, 12:15 PM CDT
In force: 48 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Ford County, IL, Iroquois County, IL, Livingston County, IL, Benton County, IN, Newton County, IN

The radar

The Chicago radar (KLOT), 96 km from the middle of the area, began a volume at 16:27 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, 4.5 hours before the alert went out and 92 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1065 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 469 m²/s²
0-3 km storm-relative helicity: 455 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Mar 20, 6:40 AM CDT, 4 hours 47 minutes earlier.

Area forecast discussion, Mar 20, 6:40 AM CDT, 4 hours 47 minutes before

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Hazardous weather outlook, Mar 20, 9:52 AM CDT, 1 hour 35 minutes before

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In the hours before

Special weather statement, Mar 20, 10:47 AM CDT, 40 minutes before

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Local storm report, Mar 20, 11:04 AM CDT, 23 minutes before

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Local storm report, Mar 20, 11:14 AM CDT, 13 minutes before

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Local storm report, Mar 20, 11:15 AM CDT, 12 minutes before

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Special weather statement, Mar 20, 11:17 AM CDT, 10 minutes before

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Local storm report, Mar 20, 11:23 AM CDT, 4 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
Mar 20, 1:42 AM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Kane	63 min
Mar 20, 2:22 AM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Will	53 min
Mar 20, 3:14 AM CDT	Special Weather Statement	LOT	Will	46 min
Mar 20, 3:30 AM CDT	Special Weather Statement	LOT	Kendall	30 min
Mar 20, 3:55 AM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kendall, Will	4 hr
Mar 20, 3:59 AM CDT	Special Weather Statement	LOT	Livingston	31 min
Mar 20, 5:01 AM CDT	Areal Flood Advisory	LOT	Ford, LaSalle, Livingston	3 hr
Mar 20, 5:04 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	41 min
Mar 20, 5:31 AM CDT	Flash Flood Warning	LOT	Ford, Iroquois, Livingston	6 hr
Mar 20, 6:11 AM CDT	Special Weather Statement	LOT	Ford	49 min
Mar 20, 10:47 AM CDT	Special Weather Statement	LOT	Livingston	28 min
Mar 20, 11:05 AM CDT	Severe Thunderstorm Warning	LOT	Livingston	25 min
Mar 20, 12:15 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	45 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2017 Severe Thunderstorm Warnings in Indiana, 2017 Every severe thunderstorm warning in 2017

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.