Alert archive / Illinois / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 69, NWS Chicago, IL

June 28, 1998LaSalle County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jun 28, 1998, 3:20 AM CDT for LaSalle County, Illinois. It was in force for 40 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Jun 28, 1998, 3:20 AM CDT (08:20 UTC)
Expired
Jun 28, 1998, 4:00 AM CDT
In force
40 min
Issued by
NWS Chicago, IL
Area
Whole counties

County LaSalle County, IL

What was reported inside it

TimeReportWhereRemark
Jun 28, 3:40 AM CDTThunderstorm Wind 50Countywide, IL

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

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

IssuedProductOfficeLasted
Jun 28, 12:30 AM CDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 8.3 hours before the alert went out and 138 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 00:00Z on 1998-06-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4171 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 00:00Z on 1998-06-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 11 square meters per square second.193958Sfc1 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
4171 J/kg
Mixed-layer CIN
-42 J/kg
Mixed-layer LCL
1286 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
11 m²/s²
0-3 km storm-relative helicity
103 m²/s²
Significant tornado parameter
0.5
Supercell composite
4.1

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 27, 11:56 PM CDTSevere Thunderstorm WarningLOTBoone, Winnebago57 min
Jun 28, 2:26 AM CDTSevere Thunderstorm WarningLOTLee, Ogle, Winnebago54 min
Jun 28, 3:08 AM CDTSevere Thunderstorm WarningLOTBoone, DeKalb42 min
Jun 28, 3:45 AM CDTSevere Thunderstorm WarningLOTKane, Kendall, McHenry30 min
Jun 28, 4:00 AM CDTSevere Thunderstorm WarningLOTCook, DuPage, Will55 min
Jun 28, 4:00 AM CDTSevere Thunderstorm WarningLOTGrundy, Livingston55 min

Nearby

Severe Thunderstorm Warnings in Illinois, 1998Every severe thunderstorm warning in 1998

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.