Alert archive / Illinois / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 40, NWS Quad Cities, IA

August 21, 1987Henry County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 21, 1987, 4:57 AM CDT for Henry County, Illinois. It was in force for 33 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
Aug 21, 1987, 4:57 AM CDT (09:57 UTC)
Expired
Aug 21, 1987, 5:30 AM CDT
In force
33 min
Issued by
NWS Quad Cities, IA
Area
Whole counties

County Henry County, IL

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

What was reported inside it

TimeReportWhereRemark
Aug 21, 5:00 AM CDTThunderstorm Wind 0Henry, 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. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Peoria Regional, IL (KPIA), launched 00:00Z, 10.0 hours before the alert went out and 88 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, Peoria Regional, IL at 00:00Z on 1987-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1095 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, Peoria Regional, IL at 00:00Z on 1987-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 92 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
1095 J/kg
Mixed-layer CIN
-45 J/kg
Mixed-layer LCL
1543 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
92 m²/s²
0-3 km storm-relative helicity
231 m²/s²
Significant tornado parameter
0.4
Supercell composite
6.0

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 Quad Cities, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 12:32 AM CDTSevere Thunderstorm WarningDVNJones43 min
Aug 21, 12:39 AM CDTSevere Thunderstorm WarningDVNCedar21 min
Aug 21, 1:02 AM CDTSevere Thunderstorm WarningDVNCedar, Muscatine38 min
Aug 21, 1:49 AM CDTSevere Thunderstorm WarningDVNScott26 min
Aug 21, 2:18 AM CDTSevere Thunderstorm WarningDVNScott42 min
Aug 21, 3:31 AM CDTSevere Thunderstorm WarningDVNScott29 min
Aug 21, 4:01 AM CDTSevere Thunderstorm WarningDVNScott59 min
Aug 21, 4:57 AM CDTSevere Thunderstorm WarningDVNCedar, Clinton, Scott33 min
Aug 21, 5:28 AM CDTSevere Thunderstorm WarningDVNScott47 min
Aug 21, 5:53 AM CDTFlash Flood WarningDVNScott3 hr
Aug 21, 2:18 AM CDTSevere Thunderstorm WarningDVNHenry, Mercer, Rock Island42 min
Aug 21, 4:01 AM CDTSevere Thunderstorm WarningDVNMercer59 min

Nearby

Severe Thunderstorm Warnings in Illinois, 1987Every severe thunderstorm warning in 1987

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.