Alert archive / Illinois / Severe Thunderstorm Warnings in 2014

Severe Thunderstorm Warning 24, NWS Chicago, IL

May 12, 2014Boone County, Winnebago County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at May 12, 2014, 2:56 PM CDT for Boone County, Winnebago County, Illinois. It was in force for 49 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: May 12, 2014, 2:56 PM CDT (19:56 UTC)
Expired: May 12, 2014, 3:45 PM CDT
In force: 49 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Boone County, IL, Winnebago County, IL

The radar

The Milwaukee radar (KMKX), 80 km from the middle of the area, began a volume at 19:56 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 12, 10:02 AM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 7.9 hours before the alert went out and 148 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: 850 J/kg
Mixed-layer CIN: -21 J/kg
Mixed-layer LCL: 666 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 223 m²/s²
0-3 km storm-relative helicity: 216 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.6

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 May 12, 2:52 PM CDT, 4 minutes earlier.

Area forecast discussion, May 12, 2:52 PM CDT, 4 minutes before

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Hazardous weather outlook, May 12, 11:05 AM CDT, 3 hours 51 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
May 11, 7:43 PM CDT	Severe Thunderstorm Warning	LOT	Iroquois	62 min
May 11, 7:58 PM CDT	Flash Flood Warning	LOT	Ford, Livingston	3 hr
May 11, 9:15 PM CDT	Flash Flood Warning	LOT	Ford, Iroquois	6 hr
May 11, 9:16 PM CDT	River Flood Advisory	LOT	Will	53 hr
May 11, 11:09 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois	51 min
May 12, 9:09 AM CDT	Small Craft Advisory	LOT		12 hr
May 12, 9:34 AM CDT	Marine Dense Fog Advisory	LOT		23 hr
May 12, 5:53 PM CDT	Severe Thunderstorm Warning	LOT	LaSalle	67 min
May 12, 6:15 PM CDT	Special Weather Statement	LOT	Lake	45 min
May 12, 6:20 PM CDT	Special Marine Warning	LOT		85 min
May 12, 6:27 PM CDT	Severe Thunderstorm Warning	LOT	Cook, Lake	48 min
May 12, 6:32 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, LaSalle	58 min
May 12, 6:39 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	36 min
May 11, 7:03 PM CDT	Severe Thunderstorm Warning	LOT	Porter	42 min
May 11, 7:39 PM CDT	Flash Flood Warning	LOT	Jasper, Lake, Newton, Porter	6 hr
May 11, 7:54 PM CDT	Tornado Warning	LOT	Jasper, Newton	51 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2014 Every severe thunderstorm warning in 2014

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.