Alert archive / Montana / Mesoscale Discussions in 2012
Mesoscale Discussion 1531
The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2012, 4:25 PM MDT for 12 counties in Montana; 6 counties in North Dakota; 5 counties in South Dakota. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2012, 4:25 PM MDT (22:25 UTC)
- Expired
- Jul 21, 2012, 5:30 PM MDT
- In force
- 65 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 23 counties
Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Valley County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Golden Valley County, ND, Hettinger County, ND, Slope County, ND, Butte County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Perkins County, SD
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 10.4 hours before the alert went out and 260 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.
- Mixed-layer CAPE
- 739 J/kg
- Mixed-layer CIN
- -229 J/kg
- Mixed-layer LCL
- 1093 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 248 m²/s²
- 0-3 km storm-relative helicity
- 249 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.7
The text
As transmitted, in the capitals the NWS used until 2016.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 6:21 PM MDT | Mesoscale Discussion | SPC | Flathead, Lake, Lincoln, Mineral, Missoula, Sanders | 84 min |
| Jul 21, 4:41 PM MDT | Severe Thunderstorm Watch | SPC | Carter, Custer, Daniels, Dawson, Fallon, McCone and 5 more | 7 hr |
| Jul 20, 6:00 PM MDT | Mesoscale Discussion | SPC | Custer, Haakon, Lawrence, Meade, Pennington | 90 min |
| Jul 21, 1:54 PM MDT | Mesoscale Discussion | SPC | Butte, Custer, Fall River, Lawrence, Meade, Pennington | 96 min |
Nearby
Mesoscale Discussions in Montana, 2012Mesoscale Discussions in North Dakota, 2012Mesoscale Discussions in South Dakota, 2012Every mesoscale discussion in 2012
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.