Alert archive / Illinois / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 92, NWS Chicago, IL
NWS Chicago, IL issued this severe thunderstorm warning at Jul 20, 1998, 7:11 PM CDT for Boone County, Winnebago County, Illinois. It was in force for 64 min. 2 reports 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
- Jul 20, 1998, 7:11 PM CDT (00:11 UTC)
- Expired
- Jul 20, 1998, 8:15 PM CDT
- In force
- 64 min
- Issued by
- NWS Chicago, IL
- Area
- Whole counties
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 00:14 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.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jul 20, 7:20 PM CDT | Thunderstorm Wind 50 | Countywide, IL | |
| Jul 20, 8:10 PM CDT | Thunderstorm Wind 50 | Poplar Grove, IL | Estimated 65 mph winds snapped 2 to 3 foot diameter trees. |
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.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jul 20, 4:00 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
The nearest sounding before it
Green Bay/Straub, WI (KGRB), launched 00:00Z, 0.2 hours before the alert went out and 250 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.
- Mixed-layer CAPE
- 287 J/kg
- Mixed-layer CIN
- -50 J/kg
- Mixed-layer LCL
- 1841 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- -8 m²/s²
- 0-3 km storm-relative helicity
- 49 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
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.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 7:37 PM CDT | Severe Thunderstorm Warning | LOT | Lake, McHenry | 53 min |
| Jul 20, 7:54 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage, Kane | 51 min |
| Jul 21, 1:09 PM CDT | Severe Thunderstorm Warning | LOT | McHenry | 31 min |
| Jul 21, 1:21 PM CDT | Severe Thunderstorm Warning | LOT | Lake | 29 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; radar from the NEXRAD Level II archive.