Alert archive / Illinois / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 1, NWS Chicago, IL

April 8, 2015Ford County, Iroquois County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Apr 8, 2015, 2:31 PM CDT for Ford County, Iroquois County, Illinois. It was in force for 44 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: Apr 8, 2015, 2:31 PM CDT (19:31 UTC)
Expired: Apr 8, 2015, 3:15 PM CDT
In force: 44 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Ford County, IL, Iroquois County, IL

The radar

The Chicago radar (KLOT), 104 km from the middle of the area, began a volume at 19:33 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, 7.5 hours before the alert went out and 76 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: 195 J/kg
Mixed-layer CIN: -238 J/kg
Mixed-layer LCL: 839 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 142 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 7.7

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 Apr 8, 12:49 PM CDT, 1 hour 42 minutes earlier.

Area forecast discussion, Apr 8, 12:49 PM CDT, 1 hour 42 minutes before

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Hazardous weather outlook, Apr 8, 11:55 AM CDT, 2 hours 36 minutes before

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In the hours before

Special weather statement, Apr 8, 9:24 AM CDT, 5 hours 7 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
Apr 8, 4:03 AM CDT	Special Weather Statement	LOT	Livingston	57 min
Apr 8, 4:59 AM CDT	Special Weather Statement	LOT	Ford	61 min
Apr 8, 5:34 PM CDT	Dense Fog Advisory	LOT	Lake	15 hr
Apr 8, 5:38 AM CDT	Special Weather Statement	LOT	Jasper	37 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2015 Every severe thunderstorm warning in 2015

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.