Alert archive / Iowa / Severe Thunderstorm Watches in 2020
Severe Thunderstorm Watch 487
The Storm Prediction Center issued this severe thunderstorm watch at Sep 6, 2020, 2:53 AM CDT for 22 counties in Illinois; 39 counties in Iowa. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 6, 2020, 2:53 AM CDT (07:53 UTC)
- Expired
- Sep 6, 2020, 9:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 61 counties
Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Cerro Gordo County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Humboldt County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Kossuth County, IA, Linn County, IA, Louisa County, IA, Mahaska County, IA, Marshall County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Scott County, IA, Story County, IA, Tama County, IA, Washington County, IA, Webster County, IA, Winnebago County, IA, Worth County, IA, Wright County, IA, Bureau County, IL, Carroll County, IL, DeWitt County, IL, Henry County, IL, Jo Daviess County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Marshall County, IL, McLean County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Whiteside County, IL, Woodford County, IL
The radar
The Des Moines radar (KDMX), 143 km from the middle of the area, began a volume at 07:55 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
- 5%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 6, 2:57 AM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo, Hancock, Kossuth, Winnebago, Worth | 48 min |
| Sep 6, 3:14 AM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo, Hancock, Kossuth, Wright | 46 min |
| Sep 6, 3:14 AM CDT | Severe Thunderstorm Warning | DVN | Delaware, Dubuque, Jones | 32 min |
| Sep 6, 3:40 AM CDT | Severe Thunderstorm Warning | DMX | Butler, Cerro Gordo, Franklin, Hancock, Hardin, Wright | 50 min |
| Sep 6, 4:04 AM CDT | Severe Thunderstorm Warning | DVN | Rock Island, Whiteside | 41 min |
| Sep 6, 4:28 AM CDT | Severe Thunderstorm Warning | DVN | Cedar, Delaware, Jones, Linn | 47 min |
| Sep 6, 4:40 AM CDT | Severe Thunderstorm Warning | DVN | Bureau, Henry, Rock Island, Whiteside | 65 min |
| Sep 6, 5:41 AM CDT | Severe Thunderstorm Warning | ILX | Knox, Marshall, Stark | 49 min |
| Sep 6, 5:44 AM CDT | Severe Thunderstorm Warning | DVN | Bureau, Henry | 31 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 6, 2:32 AM CDT | Mesoscale Discussion | SPC | Carroll, Henderson, Henry, Jo Daviess, Knox, Lee and 4 more | 88 min |
| Sep 6, 5:30 AM CDT | Mesoscale Discussion | SPC | Bureau, Carroll, Henry, Jo Daviess, Knox, Mercer and 5 more | 90 min |
| Sep 5, 7:53 PM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 19 more | 2 hr |
| Sep 5, 9:34 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 47 more | 7 hr |
| Sep 5, 11:26 PM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 28 more | 94 min |
| Sep 6, 1:06 AM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 28 more | 84 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2020Severe Thunderstorm Watches in Illinois, 2020Every severe thunderstorm watch in 2020
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; radar from the NEXRAD Level II archive.