Alert archive / Illinois / Severe Thunderstorm Watches in 2004
Severe Thunderstorm Watch 222
The Storm Prediction Center issued this severe thunderstorm watch at May 20, 2004, 3:35 PM CDT for 29 counties in Illinois; 21 counties in Iowa; 8 counties in Wisconsin. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- May 20, 2004, 3:35 PM CDT (20:35 UTC)
- Expired
- May 20, 2004, 10:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
All 58 counties
Benton County, IA, Black Hawk County, IA, Buchanan County, IA, Cedar County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Marshall County, IL, McHenry County, IL, Mercer County, IL, Ogle County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Warren County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Green County, WI, Kenosha County, WI, Lafayette County, WI, Milwaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Waukesha County, WI
The radar
The Quad Cities radar (KDVN), 50 km from the middle of the area, began a volume at 20:38 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.
Warnings issued inside it
33 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 20, 6:02 PM CDT | Severe Thunderstorm Warning | MKX | Green | 43 min |
| May 20, 6:18 PM CDT | Severe Thunderstorm Warning | LOT | Winnebago | 42 min |
| May 20, 6:22 PM CDT | Severe Thunderstorm Warning | DVN | Stephenson | 53 min |
| May 20, 6:26 PM CDT | Flash Flood Warning | LOT | Winnebago | 2 hr |
| May 20, 6:32 PM CDT | Severe Thunderstorm Warning | DVN | Keokuk, Washington | 43 min |
| May 20, 6:57 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine, Walworth | 63 min |
| May 20, 7:00 PM CDT | Severe Thunderstorm Warning | LOT | Winnebago | 60 min |
| May 20, 7:13 PM CDT | Severe Thunderstorm Warning | DVN | Johnson, Washington | 62 min |
| May 20, 7:20 PM CDT | Flash Flood Warning | LOT | Boone, McHenry | 3 hr |
| May 20, 7:31 PM CDT | Flash Flood Warning | LOT | DeKalb, Kane, Lee, Ogle | 3 hr |
| May 20, 7:35 PM CDT | Severe Thunderstorm Warning | DVN | Whiteside | 55 min |
| May 20, 7:41 PM CDT | Severe Thunderstorm Warning | DVN | Louisa | 64 min |
| May 20, 7:49 PM CDT | Severe Thunderstorm Warning | LOT | Lake | 41 min |
| May 20, 7:54 PM CDT | Severe Thunderstorm Warning | DVN | Cedar | 66 min |
| May 20, 7:57 PM CDT | Flash Flood Warning | MKX | Kenosha | 2 hr |
| May 20, 8:02 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha | 28 min |
| May 20, 8:03 PM CDT | Flash Flood Warning | LOT | Cook, DuPage | 3 hr |
| May 20, 8:07 PM CDT | Severe Thunderstorm Warning | LOT | DeKalb, Kane | 53 min |
| May 20, 8:09 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage | 51 min |
| May 20, 8:14 PM CDT | Severe Thunderstorm Warning | MKX | Racine | 31 min |
| May 20, 8:15 PM CDT | Severe Thunderstorm Warning | DVN | Mercer | 60 min |
| May 20, 8:23 PM CDT | Flash Flood Warning | MKX | Racine | 97 min |
| May 20, 8:26 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Racine | 49 min |
| May 20, 8:41 PM CDT | Severe Thunderstorm Warning | ILX | Knox | 49 min |
| May 20, 8:51 PM CDT | Severe Thunderstorm Warning | DVN | Henry | 54 min |
| May 20, 8:57 PM CDT | Severe Thunderstorm Warning | LOT | Cook, DuPage | 48 min |
| May 20, 8:58 PM CDT | Severe Thunderstorm Warning | LOT | DeKalb, Kane | 47 min |
| May 20, 9:02 PM CDT | Severe Thunderstorm Warning | LOT | McHenry | 43 min |
| May 20, 9:13 PM CDT | Severe Thunderstorm Warning | ILX | Stark | 32 min |
| May 20, 9:31 PM CDT | Severe Thunderstorm Warning | DVN | Bureau, Putnam | 59 min |
| May 20, 9:37 PM CDT | Severe Thunderstorm Warning | ILX | Marshall | 53 min |
| May 20, 9:44 PM CDT | Severe Thunderstorm Warning | LOT | Cook, Lake | 31 min |
| May 20, 10:00 PM CDT | Severe Thunderstorm Warning | LOT | LaSalle, Livingston | 60 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Davenport, (KDVN), launched 12:00Z, 8.6 hours before the alert went out and 48 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
- 1924 J/kg
- Mixed-layer CIN
- -45 J/kg
- Mixed-layer LCL
- 689 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 209 m²/s²
- 0-3 km storm-relative helicity
- 197 m²/s²
- Significant tornado parameter
- 1.6
- Supercell composite
- 9.4
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 20, 11:31 AM CDT | Mesoscale Discussion | SPC | Henderson, Henry, Jo Daviess, Knox, Mercer, Rock Island and 1 more | 2 hr |
| May 19, 7:12 PM CDT | Mesoscale Discussion | SPC | Audubon, Calhoun, Carroll, Emmet, Floyd, Franklin and 15 more | 2 hr |
| May 20, 4:54 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Audubon, Boone, Cass and 33 more | 96 min |
| May 20, 5:00 PM CDT | Tornado Watch | SPC | Adair, Adams, Appanoose, Audubon, Cass, Clarke and 23 more | 5 hr |
Nearby
Severe Thunderstorm Watches in Illinois, 2004Severe Thunderstorm Watches in Iowa, 2004Severe Thunderstorm Watches in Wisconsin, 2004Every severe thunderstorm watch in 2004
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.