Alert archive / North Dakota / Mesoscale Discussions in 2018

Mesoscale Discussion 1124

July 21, 20184 states

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2018, 5:18 PM MDT for 4 states. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Jul 21, 2018, 5:18 PM MDT (23:18 UTC)
Expired: Jul 21, 2018, 6:45 PM MDT
In force: 87 min
Issued by: the Storm Prediction Center

All 25 counties

Carter County, MT, Dawson County, MT, Fallon County, MT, Richland County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Dunn County, ND, Golden Valley County, ND, Hettinger County, ND, McKenzie County, ND, Slope County, ND, Stark County, ND, Williams County, ND, Butte County, SD, Custer County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Pennington County, SD, Perkins County, SD, Campbell County, WY, Crook County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 224 km from the middle of the area, began a volume at 23:22 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 nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 11.3 hours before the alert went out and 328 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: 637 J/kg
Mixed-layer CIN: -421 J/kg
Mixed-layer LCL: 1463 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 294 m²/s²
0-3 km storm-relative helicity: 287 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 11:53 AM MDT	Mesoscale Discussion	SPC	Daniels, McCone, Richland, Roosevelt, Sheridan, Valley	3 hr
Jul 21, 1:53 PM MDT	Mesoscale Discussion	SPC	Carter, Custer, Fallon, Powder River, Prairie, Wibaux	3 hr
Jul 21, 4:11 PM MDT	Severe Thunderstorm Watch	SPC	Carter, Fallon, Richland, Wibaux	7 hr
Jul 21, 12:50 PM MDT	Mesoscale Discussion	SPC	Custer, Fall River	2 hr

Nearby

Mesoscale Discussions in North Dakota, 2018 Mesoscale Discussions in South Dakota, 2018 Mesoscale Discussions in Montana, 2018 Every mesoscale discussion in 2018

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.