Alert archive / Iowa / Severe Thunderstorm Watches in 2004
Severe Thunderstorm Watch 228
The Storm Prediction Center issued this severe thunderstorm watch at May 21, 2004, 1:20 AM CDT for 25 counties in Iowa; 24 counties in Nebraska; 4 counties in South Dakota. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- May 21, 2004, 1:20 AM CDT (06:20 UTC)
- Expired
- May 21, 2004, 7:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
All 53 counties
Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Emmet County, IA, Greene County, IA, Guthrie County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Monona County, IA, O'Brien County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Webster County, IA, Woodbury County, IA, Antelope County, NE, Boone County, NE, Boyd County, NE, Burt County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Knox County, NE, Madison County, NE, Nance County, NE, Pierce County, NE, Platte County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Washington County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Union County, SD, Yankton County, SD
The radar
The Sioux Falls radar (KFSD), 124 km from the middle of the area, began a volume at 06:19 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
4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 1:32 AM CDT | Severe Thunderstorm Warning | FSD | Cherokee | 28 min |
| May 21, 2:08 AM CDT | Severe Thunderstorm Warning | OAX | Burt, Cuming, Thurston | 37 min |
| May 21, 2:18 AM CDT | Severe Thunderstorm Warning | DMX | Crawford | 42 min |
| May 21, 2:37 AM CDT | Severe Thunderstorm Warning | DMX | Sac | 53 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
Omaha, NE (KOAX), launched 00:00Z, 6.3 hours before the alert went out and 143 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
- 238 J/kg
- Mixed-layer CIN
- -360 J/kg
- Mixed-layer LCL
- 1260 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 169 m²/s²
- 0-3 km storm-relative helicity
- 462 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 11.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 20, 7:32 PM CDT | Mesoscale Discussion | SPC | Cedar, Clinton, Des Moines, Henry, Jefferson, Keokuk and 5 more | 88 min |
| May 20, 10:03 PM CDT | Mesoscale Discussion | SPC | Fremont, Harrison, Mills, Pottawattamie | 87 min |
| May 21, 1:11 AM CDT | Mesoscale Discussion | SPC | Audubon, Boone, Buena Vista, Calhoun, Carroll, Cherokee and 27 more | 34 min |
| May 21, 2:22 AM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 47 more | 23 min |
| May 21, 2:35 AM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 22 more | 4 hr |
| May 21, 4:34 AM CDT | Mesoscale Discussion | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Buena Vista, Butler and 35 more | 56 min |
| May 21, 6:23 AM CDT | Mesoscale Discussion | SPC | Allamakee, Bremer, Butler, Cerro Gordo, Chickasaw, Clay and 20 more | 67 min |
| May 21, 9:44 AM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Buena Vista and 38 more | 3 hr |
| May 21, 10:25 AM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 37 more | 6 hr |
| May 21, 1:59 PM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 9 more | 2 hr |
| May 21, 2:45 PM CDT | Tornado Watch | SPC | Allamakee, Audubon, Benton, Black Hawk, Boone, Bremer and 59 more | 7 hr |
| May 21, 6:33 PM CDT | Mesoscale Discussion | SPC | Lyon, Plymouth, Sioux, Woodbury | 57 min |
| May 20, 10:30 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Buffalo, Butler, Chase, Clay, Colfax and 32 more | 6 hr |
| May 21, 2:22 PM CDT | Mesoscale Discussion | SPC | Banner, Box Butte, Cheyenne, Dawes, Kimball, Morrill and 3 more | 113 min |
| May 21, 3:05 PM CDT | Severe Thunderstorm Watch | SPC | Arthur, Banner, Box Butte, Cheyenne, Dawes, Deuel and 8 more | 5 hr |
| May 21, 4:57 PM CDT | Mesoscale Discussion | SPC | Blaine, Brown, Cherry, Hooker, Keya Paha, Logan and 2 more | 93 min |
| May 21, 5:35 PM CDT | Mesoscale Discussion | SPC | Adams, Antelope, Boone, Buffalo, Burt, Butler and 35 more | 115 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2004Severe Thunderstorm Watches in Nebraska, 2004Severe Thunderstorm Watches in South Dakota, 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.