Alert archive / Iowa / Severe Thunderstorm Watches in 2017
Severe Thunderstorm Watch 406
The Storm Prediction Center issued this severe thunderstorm watch at Jul 9, 2017, 9:40 PM CDT for 28 counties in Iowa; 11 counties in Minnesota. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 9, 2017, 9:40 PM CDT (02:40 UTC)
- Expired
- Jul 10, 2017, 3:00 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 39 counties
Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Butler County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clay County, IA, Clayton County, IA, Dickinson County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Kossuth County, IA, Mitchell County, IA, Palo Alto County, IA, Pocahontas County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Cottonwood County, MN, Dodge County, MN, Fillmore County, MN, Houston County, MN, Jackson County, MN, Lyon County, MN, Mower County, MN, Murray County, MN, Olmsted County, MN, Wabasha County, MN, Winona County, MN
The radar
The Minneapolis radar (KMPX), 165 km from the middle of the area, began a volume at 02:39 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
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 9, 9:56 PM CDT | Severe Thunderstorm Warning | FSD | Lyon | 49 min |
| Jul 9, 11:25 PM CDT | Severe Thunderstorm Warning | DMX | Winnebago, Worth | 50 min |
| Jul 10, 12:46 AM CDT | Severe Thunderstorm Warning | DMX | Hancock, Kossuth, Winnebago | 44 min |
| Jul 10, 12:50 AM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo, Hancock, Winnebago, Worth | 40 min |
| Jul 10, 1:28 AM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo, Franklin, Hancock, Winnebago, Wright | 47 min |
| Jul 10, 2:09 AM CDT | Severe Thunderstorm Warning | DMX | Butler, Franklin, Grundy, Hardin, Wright | 36 min |
| Jul 10, 2:44 AM CDT | Severe Thunderstorm Warning | DMX | Grundy, Hardin, Tama | 46 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
Minneapolis, MN (KMPX), launched 00:00Z, 2.7 hours before the alert went out and 165 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
- 627 J/kg
- Mixed-layer CIN
- -187 J/kg
- Mixed-layer LCL
- 1764 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 222 m²/s²
- 0-3 km storm-relative helicity
- 278 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.6
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 9, 9:10 PM CDT | Mesoscale Discussion | SPC | Allamakee, Bremer, Butler, Cerro Gordo, Chickasaw, Clayton and 16 more | 65 min |
| Jul 9, 11:45 PM CDT | Mesoscale Discussion | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 23 more | 60 min |
| Jul 10, 1:49 AM CDT | Mesoscale Discussion | SPC | Benton, Buchanan, Cedar, Clinton, Davis, Delaware and 26 more | 116 min |
| Jul 10, 2:43 AM CDT | Mesoscale Discussion | SPC | Butler, Franklin, Grundy, Hamilton, Hardin, Jasper and 7 more | 2 hr |
| Jul 10, 6:34 PM CDT | Mesoscale Discussion | SPC | Appanoose, Davis, Decatur, Van Buren, Wayne | 86 min |
| Jul 9, 7:05 PM CDT | Tornado Watch | SPC | Anoka, Benton, Blue Earth, Brown, Carver, Chippewa and 34 more | 7 hr |
Nearby
Severe Thunderstorm Watches in Iowa, 2017Severe Thunderstorm Watches in Minnesota, 2017Every severe thunderstorm watch in 2017
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.