Alert archive / South Dakota / Mesoscale Discussions in 2011

Mesoscale Discussion 1951

August 11, 20114 counties in North Dakota; 6 counties in South Dakota; Campbell County, Crook County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2011, 8:55 PM MDT for 4 counties in North Dakota; 6 counties in South Dakota; Campbell County, Crook County, Wyoming. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: Aug 11, 2011, 8:55 PM MDT (02:55 UTC)
Expired: Aug 11, 2011, 10:00 PM MDT
In force: 65 min
Issued by: the Storm Prediction Center

Counties Adams County, ND, Bowman County, ND, Hettinger County, ND, Slope County, ND, Butte County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Perkins County, SD, Ziebach County, SD, Campbell County, WY, Crook County, WY

The radar

The Rapid City radar (KUDX), 112 km from the middle of the area, began a volume at 02:58 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

Rapid City, SD (KUNR), launched 00:00Z, 2.9 hours before the alert went out and 115 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: 1555 J/kg
Mixed-layer CIN: -108 J/kg
Mixed-layer LCL: 1592 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: -74 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: -0.2
Supercell composite: -4.1

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, 6:16 PM MDT	Severe Thunderstorm Watch	SPC	Adams, Bowman, Hettinger, Slope	4 hr
Aug 12, 12:18 PM MDT	Mesoscale Discussion	SPC	Barnes, Cass, Dickey, Eddy, Foster, Grand Forks and 13 more	57 min
Aug 12, 12:47 PM MDT	Severe Thunderstorm Watch	SPC	Barnes, Benson, Cass, Dickey, Eddy, Foster and 13 more	6 hr
Aug 12, 2:44 PM MDT	Mesoscale Discussion	SPC	Barnes, Benson, Cass, Dickey, Eddy, Foster and 16 more	91 min
Aug 11, 6:19 PM MDT	Severe Thunderstorm Watch	SPC	Bon Homme, Brookings, Charles Mix, Clay, Davison, Douglas and 13 more	5 hr
Aug 11, 8:42 PM MDT	Mesoscale Discussion	SPC	Beadle, Bon Homme, Brookings, Clay, Davison, Douglas and 13 more	63 min

Nearby

Mesoscale Discussions in South Dakota, 2011 Mesoscale Discussions in North Dakota, 2011 Mesoscale Discussions in Wyoming, 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.