Alert archive / Iowa / Severe Thunderstorm Watches in 2020
Severe Thunderstorm Watch 355
The Storm Prediction Center issued this severe thunderstorm watch at Jul 11, 2020, 10:04 AM CDT for 7 counties in Illinois; 14 counties in Iowa. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 11, 2020, 10:04 AM CDT (15:04 UTC)
- Expired
- Jul 11, 2020, 12:37 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 21 counties
Benton County, IA, Cedar County, IA, Clinton County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Washington County, IA, Henderson County, IL, Henry County, IL, Knox County, IL, Mercer County, IL, Rock Island County, IL, Stark County, IL, Warren County, IL
The radar
The Quad Cities radar (KDVN), 49 km from the middle of the area, began a volume at 15:05 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
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 11, 10:11 AM CDT | Severe Thunderstorm Warning | DVN | Jones, Linn | 64 min |
| Jul 11, 10:52 AM CDT | Severe Thunderstorm Warning | DVN | Cedar | 38 min |
| Jul 11, 11:30 AM CDT | Severe Thunderstorm Warning | DVN | Cedar, Muscatine | 19 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
Davenport, (KDVN), launched 12:00Z, 3.1 hours before the alert went out and 56 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
- 183 J/kg
- Mixed-layer CIN
- -228 J/kg
- Mixed-layer LCL
- 1573 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 63 m²/s²
- 0-3 km storm-relative helicity
- 136 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.3
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 11, 9:36 AM CDT | Mesoscale Discussion | SPC | Cass, Fulton, Henderson, Henry, Knox, Logan and 11 more | 114 min |
| Jul 11, 3:58 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Bureau, Carroll, Champaign, Coles, DeKalb and 35 more | 8 hr |
| Jul 11, 1:23 AM CDT | Mesoscale Discussion | SPC | Fremont, Harrison, Mills, Montgomery, Page, Pottawattamie | 2 hr |
| Jul 11, 11:36 AM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Buena Vista, Clay, Dickinson, Emmet and 14 more | 114 min |
| Jul 11, 1:10 PM CDT | Severe Thunderstorm Watch | SPC | Black Hawk, Boone, Bremer, Buena Vista, Butler, Cerro Gordo and 29 more | 7 hr |
| Jul 11, 2:52 PM CDT | Mesoscale Discussion | SPC | Black Hawk, Bremer, Butler, Cerro Gordo, Chickasaw, Fayette and 16 more | 83 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.