Alert archive / Illinois / Winter Storm Warnings in 2011

Winter Storm Warning 1, NWS Chicago, IL

February 19, 20114 counties in Illinois

NWS Chicago, IL issued this winter storm warning at Feb 19, 2011, 3:51 PM CST for 4 counties in Illinois. It took effect at Feb 20, 2011, 3:00 AM CST. It was in force for 7 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
Feb 19, 2011, 3:51 PM CST (21:51 UTC)
In effect from
Feb 20, 2011, 3:00 AM CST
Expired
Feb 20, 2011, 10:00 AM CST
In force
7 hr
Issued by
NWS Chicago, IL

Counties Boone County, IL, Lake County, IL, McHenry County, IL, Winnebago County, IL

The radar

The Milwaukee radar (KMKX), 71 km from the middle of the area, began a volume at 21:57 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

Green Bay/Straub, WI (KGRB), launched 12:00Z, 9.9 hours before the alert went out and 242 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-pSkew-T log-p diagram, Green Bay/Straub, WI at 12:00Z on 2011-02-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Green Bay/Straub, WI at 12:00Z on 2011-02-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -260 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
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
1172 m above ground
0-6 km bulk shear
78 kt
0-1 km storm-relative helicity
-260 m²/s²
0-3 km storm-relative helicity
-197 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 winter storm 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 winter storm warning went out at Feb 19, 3:29 PM CST, 22 minutes earlier.

Area forecast discussion, Feb 19, 3:29 PM CST, 22 minutes before
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Hazardous weather outlook, Feb 19, 4:58 AM CST, 10 hours 53 minutes before
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      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        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.

IssuedProductOfficeCountiesLasted
Feb 19, 4:44 AM CSTWinter Storm WatchLOTBoone, Lake, McHenry, Winnebago11 hr
Feb 19, 9:46 AM CSTGale WatchLOT17 hr
Feb 19, 2:39 PM CSTSmall Craft AdvisoryLOT3 days
Feb 19, 3:51 PM CSTWinter Weather AdvisoryLOTDeKalb, DuPage, Kane, Ogle18 hr
Feb 19, 10:33 AM CSTRiver Flood AdvisoryLOTNewton24 hr

Nearby

Winter Storm Warnings in Illinois, 2011Every winter storm warning in 2011

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.