Alert archive / Illinois / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 15, NWS Chicago, IL

April 25, 2008DeKalb County, LaSalle County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Apr 25, 2008, 5:37 PM CDT for DeKalb County, LaSalle County, Illinois. It was in force for 15 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 25, 2008, 5:37 PM CDT (22:37 UTC)
Expired
Apr 25, 2008, 5:52 PM CDT
In force
15 min
Issued by
NWS Chicago, IL
Area
Storm-based polygon

Counties DeKalb County, IL, LaSalle County, IL

The radar

The Chicago radar (KLOT), 62 km from the middle of the area, began a volume at 22:37 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.

IssuedProductOfficeLasted
Apr 25, 1:27 PM CDTSevere Thunderstorm WatchSPC7 hr
Apr 25, 3:41 PM CDTTornado WatchSPC4 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 10.6 hours before the alert went out and 139 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, Davenport, at 12:00Z on 2008-04-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1215 joules per kilogram.LCLLFCEL10008507005003002001001 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, Davenport, at 12:00Z on 2008-04-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 157 square meters per square second.19395878Sfc1 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
1215 J/kg
Mixed-layer CIN
-45 J/kg
Mixed-layer LCL
678 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
157 m²/s²
0-3 km storm-relative helicity
204 m²/s²
Significant tornado parameter
1.1
Supercell composite
7.5

Open this sounding in Storm Lab

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 24, 8:43 PM CDTRiver Flood WatchLOTWinnebago37 hr
Apr 25, 9:30 AM CDTSevere Thunderstorm WarningLOTOgle60 min
Apr 25, 10:04 AM CDTSevere Thunderstorm WarningLOTKane31 min
Apr 25, 4:09 PM CDTSevere Thunderstorm WarningLOTOgle, Winnebago36 min
Apr 25, 4:17 PM CDTSevere Thunderstorm WarningLOTGrundy, LaSalle, Livingston58 min
Apr 25, 4:26 PM CDTSevere Thunderstorm WarningLOTBoone, McHenry32 min
Apr 25, 5:38 PM CDTSevere Thunderstorm WarningLOTDeKalb, Lee, Ogle37 min
Apr 25, 5:51 PM CDTSevere Thunderstorm WarningLOTCook, DuPage, Kane, Lake, McHenry45 min
Apr 25, 6:43 PM CDTSevere Thunderstorm WarningLOTGrundy, Kendall, Will47 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2008Every severe thunderstorm warning in 2008

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.