Alert archive / Montana / Mesoscale Discussions in 2008

Mesoscale Discussion 1864

July 22, 20089 counties in Montana; Divide County, McKenzie County, Williams County, North Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 22, 2008, 5:05 PM MDT for 9 counties in Montana; Divide County, McKenzie County, Williams County, North Dakota. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: Jul 22, 2008, 5:05 PM MDT (23:05 UTC)
Expired: Jul 22, 2008, 6:00 PM MDT
In force: 55 min
Issued by: the Storm Prediction Center

Counties Daniels County, MT, Dawson County, MT, Garfield County, MT, McCone County, MT, Petroleum County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Valley County, MT, Divide County, ND, McKenzie County, ND, Williams County, ND

The radar

The Glasgow radar (KGGW), 80 km from the middle of the area, began a volume at 23:07 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 731Jul 22, 5:05 PM MDT

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 11.1 hours before the alert went out and 79 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: 1077 J/kg
Mixed-layer CIN: -319 J/kg
Mixed-layer LCL: 1928 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 176 m²/s²
0-3 km storm-relative helicity: 181 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
Jul 22, 1:00 PM MDT	Severe Thunderstorm Watch	SPC	Beaverhead, Gallatin, Madison	8 hr
Jul 22, 3:12 PM MDT	Mesoscale Discussion	SPC	Big Horn, Broadwater, Carbon, Cascade, Custer, Deer Lodge and 19 more	63 min
Jul 22, 3:24 PM MDT	Severe Thunderstorm Watch	SPC	Big Horn, Carbon, Carter, Custer, Fallon, Golden Valley and 9 more	10 hr
Jul 22, 5:08 PM MDT	Severe Thunderstorm Watch	SPC	Daniels, Dawson, Garfield, McCone, Petroleum, Phillips and 6 more	8 hr

Nearby

Mesoscale Discussions in Montana, 2008 Mesoscale Discussions in North Dakota, 2008 Every mesoscale discussion in 2008

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.