Alert archive / Illinois / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 103, NWS Chicago, IL

July 7, 2017Lake County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 7, 2017, 12:48 AM CDT for Lake County, Illinois. It was in force for 45 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: Jul 7, 2017, 12:48 AM CDT (05:48 UTC)
Expired: Jul 7, 2017, 1:33 AM CDT
In force: 45 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Lake County, IL

The radar

The Chicago radar (KLOT), 85 km from the middle of the area, began a volume at 05:48 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 00:00Z, 5.8 hours before the alert went out and 233 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: 1175 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 1720 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 186 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 5.4

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 Jul 7, 12:41 AM CDT, 7 minutes earlier.

Area forecast discussion, Jul 7, 12:41 AM CDT, 7 minutes before

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Hazardous weather outlook, Jul 6, 3:00 PM CDT, 9 hours 48 minutes before

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        The site you requested is temporarily down for maintenance or an unexpected outage.
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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 7, 12:45 AM CDT	Special Marine Warning	LOT		90 min
Jul 7, 6:36 AM CDT	Special Marine Warning	LOT		39 min
Jul 7, 7:55 AM CDT	Special Weather Statement	LOT	Lake	20 min
Jul 7, 8:14 AM CDT	Special Marine Warning	LOT		46 min
Jul 7, 8:19 AM CDT	Special Weather Statement	LOT	Cook	26 min
Jul 7, 8:56 AM CDT	Special Marine Warning	LOT		49 min
Jul 7, 11:49 AM CDT	Severe Thunderstorm Warning	LOT	Cook	41 min
Jul 7, 12:36 PM CDT	Severe Thunderstorm Warning	LOT	Will	27 min
Jul 7, 12:50 PM CDT	Special Weather Statement	LOT	Kankakee	25 min
Jul 7, 6:45 AM CDT	Special Weather Statement	LOT	Porter	30 min
Jul 7, 7:04 AM CDT	Severe Thunderstorm Warning	LOT	Porter	26 min
Jul 7, 9:11 AM CDT	Severe Thunderstorm Warning	LOT	Porter	19 min
Jul 7, 11:53 AM CDT	Severe Thunderstorm Warning	LOT	Jasper, Porter	37 min
Jul 7, 12:53 PM CDT	Special Weather Statement	LOT	Jasper	22 min
Jul 7, 1:13 PM CDT	Severe Thunderstorm Warning	LOT	Jasper, Lake, Newton	47 min
Jul 7, 1:41 PM CDT	Severe Thunderstorm Warning	LOT	Jasper	19 min
Jul 7, 3:00 PM CDT	Special Weather Statement	LOT	Benton	30 min

Nearby

Severe Thunderstorm Warnings in Illinois, 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.