Alert archive / North Dakota / Mesoscale Discussions in 2011

Mesoscale Discussion 1818

August 1, 201116 counties in North Dakota; 6 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2011, 12:33 PM MDT for 16 counties in North Dakota; 6 counties in South Dakota. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: Aug 1, 2011, 12:33 PM MDT (18:33 UTC)
Expired: Aug 1, 2011, 1:30 PM MDT
In force: 57 min
Issued by: the Storm Prediction Center

All 22 counties

Adams County, ND, Burleigh County, ND, Emmons County, ND, Grant County, ND, Hettinger County, ND, Kidder County, ND, McHenry County, ND, McLean County, ND, Mercer County, ND, Morton County, ND, Oliver County, ND, Pierce County, ND, Sheridan County, ND, Sioux County, ND, Stark County, ND, Ward County, ND, Butte County, SD, Corson County, SD, Dewey County, SD, Harding County, SD, Perkins County, SD, Ziebach County, SD

The radar

The Bismarck radar (KBIS), 80 km from the middle of the area, began a volume at 18:33 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 713Aug 1, 1:20 PM MDT

The nearest sounding before it

Bismarck Municip, ND (KBIS), launched 12:00Z, 6.6 hours before the alert went out and 85 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: 2236 J/kg
Mixed-layer CIN: -306 J/kg
Mixed-layer LCL: 910 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 341 m²/s²
0-3 km storm-relative helicity: 373 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 7.3

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
Jul 31, 7:16 PM MDT	Mesoscale Discussion	SPC	Adams, Grant, Morton, Sioux	89 min
Jul 31, 9:26 PM MDT	Severe Thunderstorm Watch	SPC	Barnes, Benson, Burleigh, Cass, Cavalier, Dickey and 25 more	8 hr
Jul 31, 11:35 PM MDT	Mesoscale Discussion	SPC	Barnes, Burleigh, Cass, Eddy, Emmons, Foster and 12 more	85 min
Aug 1, 1:31 AM MDT	Mesoscale Discussion	SPC	Cass, Grand Forks, Griggs, Nelson, Steele, Traill and 1 more	89 min
Aug 1, 3:57 AM MDT	Severe Thunderstorm Watch	SPC	Barnes, Cass, Dickey, Eddy, Foster, Griggs and 11 more	7 hr
Aug 1, 10:52 AM MDT	Severe Thunderstorm Watch	SPC	Barnes, Cass, Grand Forks, Griggs, Nelson, Ransom and 4 more	7 hr
Aug 1, 1:19 PM MDT	Severe Thunderstorm Watch	SPC	Adams, Bowman, Burleigh, Emmons, Grant, Hettinger and 10 more	6 hr
Aug 1, 2:53 PM MDT	Mesoscale Discussion	SPC	Barnes, Cass, Grand Forks, Griggs, Nelson, Ransom and 3 more	67 min
Aug 1, 4:57 PM MDT	Mesoscale Discussion	SPC	Adams, Barnes, Benson, Burleigh, Cavalier, Dickey and 23 more	2 hr
Aug 1, 5:10 PM MDT	Mesoscale Discussion	SPC	Adams, Barnes, Benson, Burleigh, Cavalier, Dickey and 23 more	2 hr

Nearby

Mesoscale Discussions in North Dakota, 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.