Alert archive / South Dakota / Mesoscale Discussions in 2018

Mesoscale Discussion 943

June 29, 2018Carter County, Powder River County, Montana; 10 counties in South Dakota; 7 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jun 29, 2018, 2:29 PM MDT for Carter County, Powder River County, Montana; 10 counties in South Dakota; 7 counties in Wyoming. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Jun 29, 2018, 2:29 PM MDT (20:29 UTC)
Expired: Jun 29, 2018, 4:00 PM MDT
In force: 91 min
Issued by: the Storm Prediction Center

Counties Carter County, MT, Powder River County, MT, Butte County, SD, Custer County, SD, Fall River County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Oglala Lakota County, SD, Pennington County, SD, Perkins County, SD, Ziebach County, SD, Campbell County, WY, Converse County, WY, Crook County, WY, Johnson County, WY, Niobrara County, WY, Sheridan County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 140 km from the middle of the area, began a volume at 20:32 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 243Jun 29, 5:15 PM MDT

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 8.5 hours before the alert went out and 350 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: 256 J/kg
Mixed-layer CIN: -222 J/kg
Mixed-layer LCL: 1500 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 59 m²/s²
0-3 km storm-relative helicity: 84 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
Jun 28, 8:06 PM MDT	Mesoscale Discussion	SPC	Carter, Custer, Dawson, Fallon, Garfield, McCone and 7 more	84 min
Jun 29, 11:23 AM MDT	Mesoscale Discussion	SPC	Big Horn, Carbon	97 min
Jun 29, 1:06 PM MDT	Severe Thunderstorm Watch	SPC	Carter, Powder River	9 hr
Jun 28, 9:54 PM MDT	Severe Thunderstorm Watch	SPC	Campbell, Corson	9 hr
Jun 29, 1:02 AM MDT	Mesoscale Discussion	SPC	Campbell, Corson, McPherson	118 min
Jun 29, 4:57 PM MDT	Mesoscale Discussion	SPC	Bennett, Campbell, Corson, Dewey, Haakon, Jackson and 8 more	63 min
Jun 29, 5:19 PM MDT	Severe Thunderstorm Watch	SPC	Bennett, Buffalo, Campbell, Corson, Dewey, Edmunds and 18 more	8 hr
Jun 29, 12:30 PM MDT	Mesoscale Discussion	SPC	Big Horn, Campbell, Converse, Crook, Johnson, Natrona and 4 more	60 min
Jun 29, 4:31 PM MDT	Mesoscale Discussion	SPC	Goshen, Laramie, Platte	89 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.