Alert archive / Iowa / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 224
The Storm Prediction Center issued this severe thunderstorm watch at May 1, 2012, 9:18 PM CDT for 60 counties in Iowa; 29 counties in Nebraska. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- May 1, 2012, 9:18 PM CDT (02:18 UTC)
- Expired
- May 2, 2012, 4:00 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 89 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clarke County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Dickinson County, IA, Emmet 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, Ida County, IA, Jasper County, IA, Kossuth County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monona County, IA, Monroe County, IA, Montgomery County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Story County, IA, Tama County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Adams County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Hall County, NE, Hamilton County, NE, Lancaster County, NE, Merrick County, NE, Nance County, NE, Otoe County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, York County, NE
The radar
The Omaha radar (KOAX), 119 km from the middle of the area, began a volume at 02:20 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
- 50%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 95%
Warnings issued inside it
31 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 9:22 PM CDT | Severe Thunderstorm Warning | FSD | Dickinson, Osceola | 38 min |
| May 1, 9:23 PM CDT | Severe Thunderstorm Warning | GID | Polk | 52 min |
| May 1, 9:28 PM CDT | Severe Thunderstorm Warning | GID | Clay, Fillmore, Hamilton, York | 38 min |
| May 1, 9:29 PM CDT | Tornado Warning | FSD | Clay, O'Brien | 46 min |
| May 1, 9:32 PM CDT | Severe Thunderstorm Warning | GID | Hamilton | 43 min |
| May 1, 9:41 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Cherokee, Clay, Dickinson, O'Brien, Osceola | 34 min |
| May 1, 9:44 PM CDT | Tornado Warning | FSD | Clay | 31 min |
| May 1, 9:55 PM CDT | Severe Thunderstorm Warning | GID | York | 50 min |
| May 1, 9:59 PM CDT | Severe Thunderstorm Warning | DMX | Emmet, Palo Alto | 46 min |
| May 1, 10:11 PM CDT | Severe Thunderstorm Warning | GID | Hamilton, York | 34 min |
| May 1, 10:13 PM CDT | Severe Thunderstorm Warning | FSD | Buena Vista, Clay, Dickinson | 17 min |
| May 1, 10:22 PM CDT | Severe Thunderstorm Warning | OAX | Seward | 23 min |
| May 1, 10:44 PM CDT | Severe Thunderstorm Warning | GID | Polk, York | 37 min |
| May 1, 10:45 PM CDT | Severe Thunderstorm Warning | DMX | Kossuth, Palo Alto | 45 min |
| May 1, 11:24 PM CDT | Severe Thunderstorm Warning | DMX | Humboldt, Webster, Wright | 51 min |
| May 1, 11:35 PM CDT | Severe Thunderstorm Warning | DMX | Crawford | 25 min |
| May 1, 11:39 PM CDT | Severe Thunderstorm Warning | OAX | Seward | 24 min |
| May 2, 12:00 AM CDT | Severe Thunderstorm Warning | OAX | Lancaster, Seward | 30 min |
| May 2, 12:01 AM CDT | Severe Thunderstorm Warning | DMX | Carroll, Crawford, Sac | 44 min |
| May 2, 12:38 AM CDT | Severe Thunderstorm Warning | DMX | Carroll, Crawford, Greene, Sac | 52 min |
| May 2, 1:02 AM CDT | Severe Thunderstorm Warning | DMX | Audubon, Guthrie | 43 min |
| May 2, 1:07 AM CDT | Severe Thunderstorm Warning | DMX | Boone, Carroll, Dallas, Greene, Guthrie | 38 min |
| May 2, 1:24 AM CDT | Tornado Warning | DMX | Boone | 36 min |
| May 2, 1:27 AM CDT | Severe Thunderstorm Warning | DMX | Boone, Hamilton, Story, Webster | 48 min |
| May 2, 1:39 AM CDT | Severe Thunderstorm Warning | DMX | Boone, Polk, Story | 51 min |
| May 2, 1:42 AM CDT | Severe Thunderstorm Warning | OAX | Pottawattamie | 33 min |
| May 2, 1:47 AM CDT | Tornado Warning | DMX | Boone, Hamilton, Hardin, Story | 28 min |
| May 2, 1:53 AM CDT | Severe Thunderstorm Warning | DMX | Dallas, Polk | 52 min |
| May 2, 2:04 AM CDT | Severe Thunderstorm Warning | DMX | Grundy, Hardin, Marshall, Story | 41 min |
| May 2, 2:37 AM CDT | Severe Thunderstorm Warning | DMX | Black Hawk, Grundy, Marshall, Tama | 36 min |
| May 2, 3:18 AM CDT | Severe Thunderstorm Warning | DMX | Jasper, Mahaska, Marion, Poweshiek | 15 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 00:00Z, 2.3 hours before the alert went out and 119 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
- 1502 J/kg
- Mixed-layer CIN
- -30 J/kg
- Mixed-layer LCL
- 1477 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 75 m²/s²
- 0-3 km storm-relative helicity
- 122 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 5.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 7:30 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Harrison, Ida, Monona, Plymouth and 1 more | 2 hr |
| May 1, 11:08 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 47 more | 2 hr |
| May 2, 2:02 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Boone, Carroll, Cass and 22 more | 58 min |
| May 2, 3:34 PM CDT | Mesoscale Discussion | SPC | Clay, Dickinson, Emmet, Lyon, O'Brien, Osceola and 2 more | 86 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2012Severe Thunderstorm Watches in Nebraska, 2012Every severe thunderstorm watch in 2012
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.