Alert archive / Iowa / Mesoscale Discussions in 2007

Mesoscale Discussion 1844

August 22, 200719 counties in Iowa; 17 counties in Nebraska; 11 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 22, 2007, 6:45 AM CDT for 19 counties in Iowa; 17 counties in Nebraska; 11 counties in South Dakota. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Aug 22, 2007, 6:45 AM CDT (11:45 UTC)
Expired: Aug 22, 2007, 7:45 AM CDT
In force: 60 min
Issued by: the Storm Prediction Center

All 47 counties

Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Harrison County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Woodbury County, IA, Antelope County, NE, Boyd County, NE, Brown County, NE, Burt County, NE, Cedar County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Rock County, NE, Stanton County, NE, Thurston County, NE, Wayne County, NE, Bon Homme County, SD, Charles Mix County, SD, Clay County, SD, Douglas County, SD, Gregory County, SD, Hutchinson County, SD, Lincoln County, SD, Tripp County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 132 km from the middle of the area, began a volume at 11:48 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.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 11.8 hours before the alert went out and 187 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 2524 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 1850 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 47 m²/s²
0-3 km storm-relative helicity: 172 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.8

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 21, 8:14 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Buchanan, Chickasaw, Clayton, Delaware, Dubuque and 5 more	8 hr
Aug 21, 10:49 PM CDT	Mesoscale Discussion	SPC	Allamakee, Audubon, Benton, Black Hawk, Boone, Bremer and 37 more	86 min
Aug 22, 2:13 AM CDT	Mesoscale Discussion	SPC	Jackson	62 min
Aug 22, 10:12 AM CDT	Mesoscale Discussion	SPC	Buena Vista, Calhoun, Cherokee, Clay, Crawford, Humboldt and 8 more	93 min
Aug 22, 2:37 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Audubon, Benton, Black Hawk and 40 more	83 min
Aug 22, 3:20 PM CDT	Severe Thunderstorm Watch	SPC	Fremont, Harrison, Mills, Montgomery, Page, Pottawattamie and 1 more	6 hr
Aug 22, 6:33 PM CDT	Mesoscale Discussion	SPC	Fremont, Harrison, Mills, Montgomery, Page, Pottawattamie and 1 more	87 min
Aug 21, 8:28 PM CDT	Mesoscale Discussion	SPC	Adams, Buffalo, Clay, Custer, Dawson, Fillmore and 20 more	92 min
Aug 22, 5:31 PM CDT	Mesoscale Discussion	SPC	Arthur, Banner, Box Butte, Cheyenne, Deuel, Garden and 5 more	89 min

Nearby

Mesoscale Discussions in Iowa, 2007 Mesoscale Discussions in Nebraska, 2007 Mesoscale Discussions in South Dakota, 2007 Every mesoscale discussion in 2007

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.