Alert archive / Iowa / Mesoscale Discussions in 2013

Mesoscale Discussion 1640

August 6, 20134 states

The Storm Prediction Center issued this mesoscale discussion at Aug 6, 2013, 5:22 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 6, 2013, 5:22 PM CDT (22:22 UTC)
Expired: Aug 6, 2013, 7:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 80 counties

Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Emmet County, IA, Hancock County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Kossuth 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, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Blue Earth County, MN, Brown County, MN, Cottonwood County, MN, Dodge County, MN, Faribault County, MN, Freeborn County, MN, Goodhue County, MN, Jackson County, MN, Le Sueur County, MN, Lyon County, MN, Martin County, MN, Murray County, MN, Nicollet County, MN, Nobles County, MN, Redwood County, MN, Rice County, MN, Rock County, MN, Steele County, MN, Waseca County, MN, Watonwan County, MN, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dawson County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Howard County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, York County, NE, Union County, SD

The radar

The Omaha radar (KOAX), 112 km from the middle of the area, began a volume at 22:22 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 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, 10.4 hours before the alert went out and 112 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: 2968 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 509 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 1 m²/s²
0-3 km storm-relative helicity: 91 m²/s²
Significant tornado parameter: 1.9
Supercell composite: 7.8

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 6, 5:07 AM CDT	Mesoscale Discussion	SPC	Fremont, Harrison, Mills, Monona, Pottawattamie, Shelby	83 min
Aug 6, 6:35 AM CDT	Severe Thunderstorm Watch	SPC	Fremont, Harrison, Mills, Monona, Montgomery, Page and 2 more	4 hr
Aug 6, 9:26 AM CDT	Mesoscale Discussion	SPC	Audubon, Cass, Fremont, Mills, Montgomery, Page and 2 more	64 min
Aug 6, 5:58 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Benton, Boone, Cass and 29 more	2 hr
Aug 6, 6:51 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Appanoose, Audubon, Cass, Cedar and 38 more	3 hr
Aug 6, 1:17 PM CDT	Mesoscale Discussion	SPC	Anoka, Benton, Blue Earth, Brown, Carver, Chippewa and 37 more	88 min
Aug 6, 2:24 PM CDT	Tornado Watch	SPC	Aitkin, Anoka, Benton, Big Stone, Carver, Cass and 33 more	7 hr
Aug 6, 6:37 PM CDT	Mesoscale Discussion	SPC	Anoka, Benton, Big Stone, Carver, Chippewa, Chisago and 31 more	113 min
Aug 5, 7:52 PM CDT	Mesoscale Discussion	SPC	Cherry	53 min
Aug 6, 2:42 AM CDT	Mesoscale Discussion	SPC	Boyd, Brown, Cherry, Holt, Keya Paha, Rock	93 min
Aug 6, 2:48 AM CDT	Severe Thunderstorm Watch	SPC	Boyd, Brown, Cherry, Holt, Keya Paha, Rock	4 hr
Aug 5, 7:56 PM CDT	Severe Thunderstorm Watch	SPC	Bennett, Butte, Custer, Fall River, Haakon, Harding and 6 more	5 hr
Aug 5, 10:18 PM CDT	Mesoscale Discussion	SPC	Haakon, Jones, Meade, Ziebach	57 min

Nearby

Mesoscale Discussions in Iowa, 2013 Mesoscale Discussions in Nebraska, 2013 Mesoscale Discussions in Minnesota, 2013 Every mesoscale discussion in 2013

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.