Alert archive / Montana / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 551
The Storm Prediction Center issued this severe thunderstorm watch at Aug 2, 2012, 2:03 PM MDT for 4 states. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 2, 2012, 2:03 PM MDT (20:03 UTC)
- Expired
- Aug 2, 2012, 9:00 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 32 counties
Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Valley County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Divide County, ND, Dunn County, ND, Golden Valley County, ND, Hettinger County, ND, McKenzie County, ND, Slope County, ND, Stark County, ND, Williams County, ND, Butte County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Perkins County, SD, Campbell County, WY, Crook County, WY
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 2, 2:19 PM MDT | Severe Thunderstorm Warning | BYZ | Carter, Powder River | 56 min |
| Aug 2, 2:40 PM MDT | Severe Thunderstorm Warning | GGW | Dawson, Prairie, Wibaux | 62 min |
| Aug 2, 3:15 PM MDT | Severe Thunderstorm Warning | BYZ | Carter, Powder River | 26 min |
| Aug 2, 3:25 PM MDT | Severe Thunderstorm Warning | UNR | Crook | 65 min |
| Aug 2, 4:16 PM MDT | Severe Thunderstorm Warning | UNR | Crook | 59 min |
| Aug 2, 5:04 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence | 56 min |
| Aug 2, 5:53 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence, Meade, Pennington | 52 min |
| Aug 2, 6:08 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Meade, Perkins, Ziebach | 67 min |
| Aug 2, 6:41 PM MDT | Severe Thunderstorm Warning | UNR | Haakon, Meade, Ziebach | 39 min |
| Aug 2, 6:44 PM MDT | Severe Thunderstorm Warning | UNR | Meade, Pennington | 76 min |
| Aug 2, 7:20 PM MDT | Severe Thunderstorm Warning | UNR | Meade, Pennington | 55 min |
| Aug 2, 8:12 PM MDT | Severe Thunderstorm Warning | UNR | Custer, Haakon, Jackson, Meade, Pennington | 63 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Rapid City, SD (KRAP), launched 12:00Z, 8.1 hours before the alert went out and 259 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2040 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- -120 m²/s²
- 0-3 km storm-relative helicity
- -117 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 2, 1:44 PM MDT | Mesoscale Discussion | SPC | Carter, Custer, Dawson, Fallon, McCone, Powder River and 4 more | 31 min |
| Aug 1, 6:35 PM MDT | Mesoscale Discussion | SPC | Brookings, Codington, Deuel, Grant, Hamlin, Kingsbury and 3 more | 55 min |
| Aug 1, 7:19 PM MDT | Mesoscale Discussion | SPC | Bon Homme, Clay, Union, Yankton | 56 min |
Nearby
Severe Thunderstorm Watches in Montana, 2012Severe Thunderstorm Watches in North Dakota, 2012Severe Thunderstorm Watches in South Dakota, 2012Every severe thunderstorm watch 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.