Alert archive / Iowa / Mesoscale Discussions in 2011
Mesoscale Discussion 834
The Storm Prediction Center issued this mesoscale discussion at May 21, 2011, 12:51 PM CDT for 5 states. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- May 21, 2011, 12:51 PM CDT (17:51 UTC)
- Expired
- May 21, 2011, 2:45 PM CDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
All 71 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Dickinson County, IA, Emmet County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Harrison County, IA, Humboldt 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, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Taylor County, IA, Webster County, IA, Woodbury County, IA, Jackson County, MN, Nobles County, MN, Rock County, MN, Atchison County, MO, Burt County, NE, Cass County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Fillmore 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, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Thayer County, NE, Thurston County, NE, Washington County, NE, Clay County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Turner County, SD, Union County, SD, Yankton County, SD
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Omaha, NE (KOAX), launched 12:00Z, 5.9 hours before the alert went out and 51 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
- 1247 J/kg
- Mixed-layer CIN
- -16 J/kg
- Mixed-layer LCL
- 607 m above ground
- 0-6 km bulk shear
- 50 kt
- 0-1 km storm-relative helicity
- -6 m²/s²
- 0-3 km storm-relative helicity
- -20 m²/s²
- Significant tornado parameter
- -0.1
- Supercell composite
- -0.4
The text
As transmitted, in the capitals the NWS used until 2016.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 2:25 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Appanoose, Audubon, Boone, Buena Vista and 49 more | 10 hr |
| May 21, 5:25 PM CDT | Mesoscale Discussion | SPC | Adams, Appanoose, Clarke, Davis, Decatur, Fremont and 9 more | 65 min |
| May 21, 6:07 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Boone, Buena Vista, Calhoun and 42 more | 53 min |
| May 21, 4:55 PM CDT | Mesoscale Discussion | SPC | Anoka, Benton, Big Stone, Blue Earth, Brown, Carver and 42 more | 95 min |
| May 21, 2:33 PM CDT | Mesoscale Discussion | SPC | Andrew, Atchison, Buchanan, Clay, Clinton, DeKalb and 4 more | 87 min |
| May 21, 5:34 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Andrew, Atchison, Buchanan, Caldwell, Carroll and 26 more | 7 hr |
| May 21, 3:41 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Clay, Fillmore, Franklin, Greeley, Hall and 10 more | 9 hr |
Nearby
Mesoscale Discussions in Iowa, 2011Mesoscale Discussions in Nebraska, 2011Mesoscale Discussions in South Dakota, 2011Every mesoscale discussion 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.