Alert archive / Iowa / Severe Thunderstorm Watches in 2009
Severe Thunderstorm Watch 686
The Storm Prediction Center issued this severe thunderstorm watch at Aug 9, 2009, 3:44 PM CDT for 4 states. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 9, 2009, 3:44 PM CDT (20:44 UTC)
- Expired
- Aug 9, 2009, 9:55 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 70 kt
All 66 counties
Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Cass County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Fremont County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hardin County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monroe County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Wayne County, IA, Brown County, KS, Clay County, KS, Cloud County, KS, Doniphan County, KS, Marshall County, KS, Nemaha County, KS, Ottawa County, KS, Pottawatomie County, KS, Republic County, KS, Riley County, KS, Washington County, KS, Andrew County, MO, Atchison County, MO, Gentry County, MO, Harrison County, MO, Holt County, MO, Mercer County, MO, Nodaway County, MO, Worth County, MO, Cass County, NE, Gage County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE
The radar
The Omaha radar (KOAX), 97 km from the middle of the area, began a volume at 20:46 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
- 20%
- 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
- 80%
Warnings issued inside it
25 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 3:55 PM CDT | Severe Thunderstorm Warning | OAX | Gage, Johnson, Nemaha, Otoe | 65 min |
| Aug 9, 4:00 PM CDT | Severe Thunderstorm Warning | DMX | Cass | 45 min |
| Aug 9, 4:19 PM CDT | Severe Thunderstorm Warning | TOP | Cloud, Republic | 41 min |
| Aug 9, 4:24 PM CDT | Severe Thunderstorm Warning | DMX | Adair | 36 min |
| Aug 9, 4:28 PM CDT | Severe Thunderstorm Warning | OAX | Fremont | 50 min |
| Aug 9, 4:53 PM CDT | Severe Thunderstorm Warning | TOP | Clay, Washington | 37 min |
| Aug 9, 4:55 PM CDT | Severe Thunderstorm Warning | EAX | Atchison | 50 min |
| Aug 9, 5:06 PM CDT | Severe Thunderstorm Warning | DMX | Dallas | 39 min |
| Aug 9, 5:12 PM CDT | Severe Thunderstorm Warning | OAX | Fremont, Page | 39 min |
| Aug 9, 5:18 PM CDT | Severe Thunderstorm Warning | DMX | Adair, Clarke, Madison, Union, Warren | 57 min |
| Aug 9, 5:25 PM CDT | Severe Thunderstorm Warning | EAX | Atchison, Nodaway | 50 min |
| Aug 9, 5:26 PM CDT | Severe Thunderstorm Warning | DMX | Polk | 49 min |
| Aug 9, 5:41 PM CDT | Severe Thunderstorm Warning | OAX | Gage | 34 min |
| Aug 9, 5:49 PM CDT | Severe Thunderstorm Warning | DMX | Marion, Warren | 41 min |
| Aug 9, 5:52 PM CDT | Severe Thunderstorm Warning | DMX | Adams, Taylor | 38 min |
| Aug 9, 5:53 PM CDT | Severe Thunderstorm Warning | DMX | Jasper, Marshall, Polk | 52 min |
| Aug 9, 6:00 PM CDT | Severe Thunderstorm Warning | TOP | Jackson, Nemaha, Pottawatomie | 30 min |
| Aug 9, 6:15 PM CDT | Severe Thunderstorm Warning | DMX | Clarke, Lucas, Warren | 45 min |
| Aug 9, 6:17 PM CDT | Severe Thunderstorm Warning | DMX | Clarke, Decatur, Ringgold, Union | 43 min |
| Aug 9, 6:25 PM CDT | Severe Thunderstorm Warning | DMX | Mahaska, Marion, Poweshiek | 50 min |
| Aug 9, 6:28 PM CDT | Severe Thunderstorm Warning | DMX | Ringgold, Taylor | 47 min |
| Aug 9, 6:33 PM CDT | Severe Thunderstorm Warning | DMX | Jasper, Marshall, Poweshiek, Tama | 57 min |
| Aug 9, 6:54 PM CDT | Severe Thunderstorm Warning | DMX | Marshall, Tama | 51 min |
| Aug 9, 7:00 PM CDT | Severe Thunderstorm Warning | DMX | Clarke, Decatur, Ringgold, Union | 45 min |
| Aug 9, 9:41 PM CDT | Severe Thunderstorm Warning | TOP | Brown, Nemaha | 49 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 12:00Z, 8.7 hours before the alert went out and 97 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
- 1138 J/kg
- Mixed-layer CIN
- -213 J/kg
- Mixed-layer LCL
- 726 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 113 m²/s²
- 0-3 km storm-relative helicity
- 135 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.9
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 5:01 AM CDT | Mesoscale Discussion | SPC | Harrison, Monona, Pottawattamie | 59 min |
| Aug 9, 5:16 AM CDT | Severe Thunderstorm Watch | SPC | Harrison, Monona, Pottawattamie, Shelby | 6 hr |
| Aug 9, 6:30 AM CDT | Mesoscale Discussion | SPC | Audubon, Black Hawk, Boone, Bremer, Butler, Calhoun and 30 more | 2 hr |
| Aug 9, 6:54 AM CDT | Severe Thunderstorm Watch | SPC | Adair, Audubon, Black Hawk, Boone, Bremer, Buena Vista and 36 more | 7 hr |
| Aug 9, 9:55 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Allamakee, Audubon, Benton, Black Hawk and 68 more | 35 min |
| Aug 9, 10:21 AM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 9 more | 8 hr |
| Aug 9, 11:16 AM CDT | Mesoscale Discussion | SPC | Harrison, Pottawattamie, Shelby | 29 min |
| Aug 9, 1:18 PM CDT | Mesoscale Discussion | SPC | Fremont, Mills, Montgomery, Page, Taylor | 27 min |
| Aug 9, 1:40 PM CDT | Mesoscale Discussion | SPC | Adair, Audubon, Black Hawk, Boone, Bremer, Butler and 23 more | 35 min |
| Aug 9, 5:49 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Clarke, Davis, Decatur and 18 more | 86 min |
| Aug 9, 5:52 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Buchanan, Cedar, Clinton, Delaware, Des Moines and 15 more | 8 hr |
| Aug 8, 8:29 PM CDT | Severe Thunderstorm Watch | SPC | Banner, Box Butte, Cheyenne, Dawes, Deuel, Garden and 5 more | 7 hr |
| Aug 8, 10:41 PM CDT | Mesoscale Discussion | SPC | Banner, Box Butte, Cheyenne, Kimball, Morrill, Scotts Bluff and 1 more | 94 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2009Severe Thunderstorm Watches in Kansas, 2009Severe Thunderstorm Watches in Nebraska, 2009Every severe thunderstorm watch in 2009
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.