Alert archive / Iowa / Severe Thunderstorm Watches in 1998
Severe Thunderstorm Watch 764
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 1998, 6:15 AM CDT for 27 counties in Iowa. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 1998, 6:15 AM CDT (11:15 UTC)
- Expired
- Jul 21, 1998, 12:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
All 27 counties
Buena Vista County, IA, Calhoun County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Emmet County, IA, Franklin County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA
The radar
The Sioux Falls radar (KFSD), 152 km from the middle of the area, began a volume at 11:19 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
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 6:16 AM CDT | Severe Thunderstorm Warning | FSD | Lyon, Sioux | 44 min |
| Jul 21, 6:40 AM CDT | Severe Thunderstorm Warning | FSD | Plymouth | 20 min |
| Jul 21, 6:43 AM CDT | Severe Thunderstorm Warning | FSD | Cherokee | 32 min |
| Jul 21, 6:43 AM CDT | Severe Thunderstorm Warning | FSD | Cherokee | 52 min |
| Jul 21, 7:03 AM CDT | Severe Thunderstorm Warning | FSD | Buena Vista | 47 min |
| Jul 21, 7:07 AM CDT | Severe Thunderstorm Warning | FSD | Clay, O'Brien | 48 min |
| Jul 21, 7:26 AM CDT | Severe Thunderstorm Warning | DMX | Palo Alto, Pocahontas | 34 min |
| Jul 21, 7:30 AM CDT | Severe Thunderstorm Warning | FSD | Dickinson | 30 min |
| Jul 21, 7:49 AM CDT | Severe Thunderstorm Warning | DMX | Emmet | 31 min |
| Jul 21, 8:00 AM CDT | Severe Thunderstorm Warning | DMX | Humboldt, Kossuth | 35 min |
| Jul 21, 8:13 AM CDT | Severe Thunderstorm Warning | DMX | Hamilton, Wright | 32 min |
| Jul 21, 8:13 AM CDT | Severe Thunderstorm Warning | DMX | Hancock, Winnebago | 32 min |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 11.3 hours before the alert went out and 221 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
- 3471 J/kg
- Mixed-layer CIN
- -121 J/kg
- Mixed-layer LCL
- 2137 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 163 m²/s²
- 0-3 km storm-relative helicity
- 419 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 26.7
The text
The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 9:00 AM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Butler, Chickasaw and 9 more | 4 hr |
Nearby
Severe Thunderstorm Watches in Iowa, 1998Every severe thunderstorm watch 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.