Alert archive / Nebraska / Mesoscale Discussions in 2011

Mesoscale Discussion 1873

August 6, 201112 counties in Iowa; 54 counties in Nebraska; Clay County, Union County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 6, 2011, 2:58 PM CDT for 12 counties in Iowa; 54 counties in Nebraska; Clay County, Union County, South Dakota. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Aug 6, 2011, 2:58 PM CDT (19:58 UTC)
Expired: Aug 6, 2011, 5:30 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 68 counties

Audubon County, IA, Cherokee County, IA, Crawford County, IA, Fremont County, IA, Harrison County, IA, Ida County, IA, Mills County, IA, Monona County, IA, Plymouth County, IA, Pottawattamie County, IA, Shelby County, IA, Woodbury County, IA, Adams County, NE, Antelope County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Custer County, NE, Dakota County, NE, Dawson County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Garfield County, NE, Gosper County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Holt County, NE, Howard County, NE, Kearney County, NE, Knox County, NE, Lancaster County, NE, Loup County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Otoe County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thayer County, NE, Thurston County, NE, Valley County, NE, Washington County, NE, Wayne County, NE, Webster County, NE, Wheeler County, NE, York County, NE, Clay County, SD, Union County, SD

The radar

The Omaha radar (KOAX), 119 km from the middle of the area, began a volume at 19:59 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.

Severe Thunderstorm Watch 732Aug 6, 5:35 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.0 hours before the alert went out and 118 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: 1049 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 487 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 49 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.7

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, 5:32 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Audubon, Boone, Calhoun, Carroll and 23 more	9 hr
Aug 5, 7:32 PM CDT	Mesoscale Discussion	SPC	Butte	88 min
Aug 5, 7:32 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Buffalo, Day, Edmunds, Faulk, Hand and 11 more	4 hr
Aug 5, 10:08 PM CDT	Mesoscale Discussion	SPC	Brown, Buffalo, Edmunds, Faulk, Hand, Hughes and 4 more	2 hr
Aug 6, 6:14 PM CDT	Mesoscale Discussion	SPC	Clark, Codington, Day, Deuel, Grant, Hamlin and 2 more	2 hr

Nearby

Mesoscale Discussions in Nebraska, 2011 Mesoscale Discussions in Iowa, 2011 Mesoscale Discussions in South Dakota, 2011 Every 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; radar from the NEXRAD Level II archive.