Alert archive / Iowa / Tornado Watches in 2007
Tornado Watch 634
The Storm Prediction Center issued this tornado watch at Aug 21, 2007, 6:47 PM CDT for 40 counties in Iowa; Burt County, Dodge County, Washington County, Nebraska. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 21, 2007, 6:47 PM CDT (23:47 UTC)
- Expired
- Aug 22, 2007, 2:00 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 70 kt
All 43 counties
Audubon County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Emmet County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Burt County, NE, Dodge County, NE, Washington County, NE
The radar
The Sioux Falls radar (KFSD), 151 km from the middle of the area, began a volume at 23:47 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 SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 95%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 80%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 95%
Warnings issued inside it
25 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 6:55 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee | 50 min |
| Aug 21, 7:16 PM CDT | Severe Thunderstorm Warning | DMX | Palo Alto | 59 min |
| Aug 21, 7:35 PM CDT | Severe Thunderstorm Warning | FSD | Woodbury | 55 min |
| Aug 21, 7:40 PM CDT | Flash Flood Warning | DMX | Palo Alto | 6 hr |
| Aug 21, 7:49 PM CDT | Tornado Warning | DMX | Humboldt, Pocahontas | 41 min |
| Aug 21, 8:04 PM CDT | Severe Thunderstorm Warning | DMX | Kossuth | 56 min |
| Aug 21, 8:07 PM CDT | Severe Thunderstorm Warning | DMX | Humboldt | 53 min |
| Aug 21, 8:24 PM CDT | Flash Flood Warning | DMX | Winnebago, Worth | 6 hr |
| Aug 21, 8:24 PM CDT | Severe Thunderstorm Warning | DMX | Humboldt, Pocahontas, Webster | 66 min |
| Aug 21, 8:29 PM CDT | Severe Thunderstorm Warning | DMX | Humboldt | 46 min |
| Aug 21, 8:33 PM CDT | Flash Flood Warning | DMX | Franklin, Humboldt, Wright | 6 hr |
| Aug 21, 8:33 PM CDT | Flash Flood Warning | DMX | Franklin, Humboldt, Pocahontas, Wright | 6 hr |
| Aug 21, 8:55 PM CDT | Severe Thunderstorm Warning | DMX | Hamilton, Wright | 65 min |
| Aug 21, 9:42 PM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo | 38 min |
| Aug 21, 10:00 PM CDT | Severe Thunderstorm Warning | DMX | Butler | 60 min |
| Aug 21, 10:06 PM CDT | Flash Flood Warning | DMX | Webster | 6 hr |
| Aug 21, 10:13 PM CDT | Flash Flood Warning | DMX | Bremer, Butler | 6 hr |
| Aug 21, 10:13 PM CDT | Severe Thunderstorm Warning | DMX | Sac | 47 min |
| Aug 21, 10:35 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Ida | 27 min |
| Aug 21, 10:45 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista | 30 min |
| Aug 21, 11:07 PM CDT | Flash Flood Warning | DMX | Webster | 6 hr |
| Aug 21, 11:16 PM CDT | Flash Flood Warning | DMX | Grundy, Hardin | 6 hr |
| Aug 21, 11:17 PM CDT | Flash Flood Warning | DMX | Grundy, Hamilton, Hardin | 6 hr |
| Aug 21, 11:32 PM CDT | Severe Thunderstorm Warning | DMX | Crawford | 28 min |
| Aug 22, 12:38 AM CDT | Severe Thunderstorm Warning | FSD | Clay | 37 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 12:00Z, 11.8 hours before the alert went out and 181 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
- 174 J/kg
- Mixed-layer CIN
- -479 J/kg
- Mixed-layer LCL
- 1438 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 46 m²/s²
- 0-3 km storm-relative helicity
- 61 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 7:03 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Buena Vista, Calhoun, Carroll and 17 more | 117 min |
| Aug 20, 7:35 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Calhoun, Carroll, Cass and 15 more | 85 min |
| Aug 20, 8:10 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Appanoose, Audubon, Black Hawk, Boone and 50 more | 5 hr |
| Aug 20, 10:06 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Boone, Buena Vista, Calhoun and 43 more | 84 min |
| Aug 21, 4:50 PM CDT | Mesoscale Discussion | SPC | Dickinson, Emmet, Howard, Mitchell, Osceola, Winnebago and 1 more | 85 min |
| Aug 21, 6:17 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Clay, Crawford, Ida, Lyon and 6 more | 88 min |
| Aug 21, 2:47 PM CDT | Mesoscale Discussion | SPC | Antelope, Blaine, Boone, Boyd, Brown, Buffalo and 44 more | 118 min |
| Aug 21, 3:45 PM CDT | Tornado Watch | SPC | Antelope, Boone, Boyd, Cedar, Colfax, Cuming and 14 more | 6 hr |
| Aug 21, 3:50 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Buffalo, Custer, Dawson, Franklin, Frontier and 16 more | 6 hr |
| Aug 21, 5:53 PM CDT | Mesoscale Discussion | SPC | Buffalo, Dawson, Frontier, Furnas, Gosper, Harlan and 5 more | 97 min |
Nearby
Tornado Watches in Iowa, 2007Tornado Watches in Nebraska, 2007Every tornado watch in 2007
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.