Alert archive / Montana / Mesoscale Discussions in 2011

Mesoscale Discussion 1869

August 5, 20116 counties in Montana; Butte County, South Dakota; Crook County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Aug 5, 2011, 6:32 PM MDT for 6 counties in Montana; Butte County, South Dakota; Crook County, Wyoming. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Aug 5, 2011, 6:32 PM MDT (00:32 UTC)
Expired: Aug 5, 2011, 8:00 PM MDT
In force: 88 min
Issued by: the Storm Prediction Center

Counties Carter County, MT, Custer County, MT, Fallon County, MT, Powder River County, MT, Rosebud County, MT, Treasure County, MT, Butte County, SD, Crook County, WY

The radar

The Rapid City radar (KUDX), 245 km from the middle of the area, began a volume at 00:34 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, 0.5 hours before the alert went out and 246 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2677 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 151 m²/s²
0-3 km storm-relative helicity: 174 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 5, 6:32 PM MDT	Severe Thunderstorm Watch	SPC	Brown, Buffalo, Day, Edmunds, Faulk, Hand and 11 more	4 hr
Aug 5, 9:08 PM MDT	Mesoscale Discussion	SPC	Brown, Buffalo, Edmunds, Faulk, Hand, Hughes and 4 more	2 hr
Aug 6, 1:58 PM MDT	Mesoscale Discussion	SPC	Clay, Union	3 hr
Aug 6, 5:14 PM MDT	Mesoscale Discussion	SPC	Clark, Codington, Day, Deuel, Grant, Hamlin and 2 more	2 hr

Nearby

Mesoscale Discussions in Montana, 2011 Mesoscale Discussions in South 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.