Alert archive / South Dakota / Mesoscale Discussions in 2018

Mesoscale Discussion 1026

July 9, 2018Powder River County, Montana; 5 counties in South Dakota; 5 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jul 9, 2018, 6:22 PM MDT for Powder River County, Montana; 5 counties in South Dakota; 5 counties in Wyoming. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: Jul 9, 2018, 6:22 PM MDT (00:22 UTC)
Expired: Jul 9, 2018, 8:15 PM MDT
In force: 113 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Powder River County, MT, Butte County, SD, Custer County, SD, Fall River County, SD, Lawrence County, SD, Pennington County, SD, Campbell County, WY, Crook County, WY, Johnson County, WY, Niobrara County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 180 km from the middle of the area, began a volume at 00:25 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

Bismarck Municip, ND (KBIS), launched 00:00Z, 0.4 hours before the alert went out and 453 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: 628 J/kg
Mixed-layer CIN: -242 J/kg
Mixed-layer LCL: 1392 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 168 m²/s²
0-3 km storm-relative helicity: 362 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 9, 6:01 PM MDT	Severe Thunderstorm Watch	SPC	Richland, Roosevelt, Sheridan	8 hr
Jul 9, 7:59 PM MDT	Mesoscale Discussion	SPC	Richland, Roosevelt, Sheridan	91 min
Jul 9, 9:24 PM MDT	Mesoscale Discussion	SPC	Roosevelt, Sheridan	96 min
Jul 10, 1:50 PM MDT	Mesoscale Discussion	SPC	Blaine, Chouteau, Custer, Daniels, Dawson, Fergus and 18 more	115 min
Jul 10, 2:14 PM MDT	Severe Thunderstorm Watch	SPC	Blaine, Broadwater, Cascade, Chouteau, Daniels, Fergus and 21 more	7 hr
Jul 10, 4:28 PM MDT	Mesoscale Discussion	SPC	Blaine, Garfield, Golden Valley, Musselshell, Petroleum, Phillips and 2 more	2 hr
Jul 10, 5:31 AM MDT	Mesoscale Discussion	SPC	Grant	29 min

Nearby

Mesoscale Discussions in South Dakota, 2018 Mesoscale Discussions in Wyoming, 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.