Alert archive / Iowa / Severe Thunderstorm Watches in 2016
Severe Thunderstorm Watch 470
The Storm Prediction Center issued this severe thunderstorm watch at Sep 6, 2016, 7:00 PM CDT for 36 counties in Iowa; 16 counties in Nebraska. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 6, 2016, 7:00 PM CDT (00:00 UTC)
- Expired
- Sep 7, 2016, 1:34 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 52 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Crawford County, IA, Dallas County, IA, Franklin County, IA, Fremont 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, Madison County, IA, Marshall County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Shelby County, IA, Story County, IA, Webster County, IA, Worth County, IA, Wright County, IA, Burt County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Douglas County, NE, Fillmore County, NE, Hamilton County, NE, Lancaster County, NE, Otoe County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Thurston County, NE, Washington County, NE, York County, NE
The radar
The Omaha radar (KOAX), 104 km from the middle of the area, began a volume at 00:04 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
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- 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%
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 00:00Z, 0.0 hours before the alert went out and 105 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
- 2597 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 1252 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 72 m²/s²
- 0-3 km storm-relative helicity
- 116 m²/s²
- Significant tornado parameter
- 1.5
- Supercell composite
- 9.8
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 6, 8:16 PM CDT | Mesoscale Discussion | SPC | Allamakee, Winneshiek | 89 min |
| Sep 6, 10:45 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Calhoun, Carroll, Cerro Gordo, Cherokee, Crawford and 15 more | 60 min |
| Sep 7, 1:00 PM CDT | Mesoscale Discussion | SPC | Cedar, Clinton, Des Moines, Dubuque, Henry, Jackson and 9 more | 3 hr |
| Sep 7, 2:47 PM CDT | Mesoscale Discussion | SPC | Adams, Appanoose, Clarke, Decatur, Fremont, Mills and 6 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Iowa, 2016Severe Thunderstorm Watches in Nebraska, 2016Every severe thunderstorm watch in 2016
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.