Alert archive / Iowa / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 495
The Storm Prediction Center issued this severe thunderstorm watch at Jun 17, 2011, 7:09 PM CDT for 24 counties in Iowa; 8 counties in Minnesota; 12 counties in Nebraska. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 17, 2011, 7:09 PM CDT (00:09 UTC)
- Expired
- Jun 17, 2011, 10:07 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
All 44 counties
Audubon County, IA, Buena Vista County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Fremont County, IA, Harrison County, IA, Ida County, IA, Lyon County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, O'Brien County, IA, Osceola County, IA, Page County, IA, Plymouth County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Burt County, NE, Cass County, NE, Cuming County, NE, Dakota County, NE, Dodge County, NE, Douglas County, NE, Lancaster County, NE, Otoe County, NE, Sarpy County, NE, Saunders County, NE, Thurston County, NE, Washington County, NE
The radar
The Sioux Falls radar (KFSD), 84 km from the middle of the area, began a volume at 00:08 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
- 2%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 17, 7:22 PM CDT | Severe Thunderstorm Warning | OAX | Dodge, Saunders | 38 min |
| Jun 17, 7:52 PM CDT | Severe Thunderstorm Warning | OAX | Cuming, Dodge | 38 min |
| Jun 17, 7:55 PM CDT | Severe Thunderstorm Warning | OAX | Dodge, Saunders | 50 min |
| Jun 17, 8:15 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Shelby | 45 min |
| Jun 17, 8:29 PM CDT | Severe Thunderstorm Warning | OAX | Dodge, Saunders | 31 min |
| Jun 17, 9:03 PM CDT | Severe Thunderstorm Warning | OAX | Saunders | 42 min |
| Jun 17, 9:44 PM CDT | Severe Thunderstorm Warning | OAX | Saunders | 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, 0.2 hours before the alert went out and 185 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
- 2547 J/kg
- Mixed-layer CIN
- -17 J/kg
- Mixed-layer LCL
- 1461 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 40 m²/s²
- 0-3 km storm-relative helicity
- 39 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 2.7
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 17, 7:22 PM CDT | Tornado Watch | SPC | Chippewa, Douglas, Kandiyohi, Lac qui Parle, McLeod, Meeker and 8 more | 7 hr |
| Jun 17, 9:01 PM CDT | Mesoscale Discussion | SPC | Big Stone, Chippewa, Grant, Kandiyohi, Lac qui Parle, McLeod and 10 more | 59 min |
| Jun 18, 2:07 AM CDT | Mesoscale Discussion | SPC | Pawnee | 53 min |
| Jun 18, 12:45 PM CDT | Mesoscale Discussion | SPC | Banner, Cheyenne, Kimball | 2 hr |
| Jun 18, 1:31 PM CDT | Severe Thunderstorm Watch | SPC | Arthur, Banner, Box Butte, Chase, Cheyenne, Deuel and 8 more | 7 hr |
| Jun 18, 5:15 PM CDT | Mesoscale Discussion | SPC | Arthur, Chase, Dawson, Deuel, Dundy, Frontier and 10 more | 90 min |
| Jun 18, 5:36 PM CDT | Severe Thunderstorm Watch | SPC | Buffalo, Custer, Dawson, Franklin, Frontier, Furnas and 14 more | 7 hr |
Nearby
Severe Thunderstorm Watches in Iowa, 2011Severe Thunderstorm Watches in Nebraska, 2011Severe Thunderstorm Watches in Minnesota, 2011Every severe thunderstorm watch in 2011
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.