Alert archive / South Dakota / Mesoscale Discussions in 2011

Mesoscale Discussion 1950

August 11, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2011, 9:42 PM CDT for 4 states. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued: Aug 11, 2011, 9:42 PM CDT (02:42 UTC)
Expired: Aug 11, 2011, 10:45 PM CDT
In force: 63 min
Issued by: the Storm Prediction Center

All 48 counties

Cherokee County, IA, Ida County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Lincoln County, MN, Pipestone County, MN, Rock County, MN, Antelope County, NE, Boone County, NE, Burt County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Knox County, NE, Madison County, NE, Nance County, NE, Pierce County, NE, Platte County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Hanson County, SD, Hutchinson County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 58 km from the middle of the area, began a volume at 02:44 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 770Aug 11, 10:20 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.7 hours before the alert went out and 196 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: 417 J/kg
Mixed-layer CIN: -214 J/kg
Mixed-layer LCL: 1393 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 110 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 11, 7:19 PM CDT	Severe Thunderstorm Watch	SPC	Cherokee, Ida, Lyon, O'Brien, Osceola, Plymouth and 2 more	5 hr
Aug 12, 1:18 PM CDT	Mesoscale Discussion	SPC	Becker, Big Stone, Chippewa, Clay, Douglas, Grant and 11 more	57 min
Aug 12, 3:44 PM CDT	Mesoscale Discussion	SPC	Becker, Beltrami, Big Stone, Cass, Chippewa, Clay and 26 more	91 min
Aug 11, 9:22 PM CDT	Mesoscale Discussion	SPC	Blaine, Boyd, Brown, Cherry, Garfield, Grant and 8 more	53 min
Aug 11, 10:16 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Buffalo, Clay, Dawson, Fillmore, Gosper and 12 more	6 hr
Aug 12, 1:45 AM CDT	Mesoscale Discussion	SPC	Adams, Blaine, Buffalo, Cherry, Clay, Custer and 27 more	2 hr
Aug 11, 7:16 PM CDT	Severe Thunderstorm Watch	SPC	Butte, Harding, Lawrence, Meade, Perkins, Ziebach	4 hr
Aug 11, 9:55 PM CDT	Mesoscale Discussion	SPC	Butte, Harding, Lawrence, Meade, Perkins, Ziebach	65 min
Aug 12, 1:47 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Clark, Codington, Day, Deuel, Edmunds and 7 more	6 hr

Nearby

Mesoscale Discussions in South Dakota, 2011 Mesoscale Discussions in Nebraska, 2011 Mesoscale Discussions in Iowa, 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.