Alert archive / North Dakota / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 500
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2012, 4:41 PM MDT for 4 states. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2012, 4:41 PM MDT (22:41 UTC)
- Expired
- Jul 21, 2012, 11:53 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 38 counties
Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, McCone County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Burke County, ND, Divide County, ND, Dunn County, ND, Golden Valley County, ND, Hettinger County, ND, McKenzie County, ND, Mountrail County, ND, Slope County, ND, Stark County, ND, Williams County, ND, Bennett County, SD, Butte County, SD, Custer County, SD, Fall River County, SD, Haakon County, SD, Harding County, SD, Jackson County, SD, Lawrence County, SD, Meade County, SD, Pennington County, SD, Perkins County, SD, Ziebach County, SD, Crook County, WY, Weston County, WY
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 50%
Warnings issued inside it
26 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 5:23 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence | 67 min |
| Jul 21, 5:29 PM MDT | Severe Thunderstorm Warning | UNR | Custer, Pennington | 10 min |
| Jul 21, 5:35 PM MDT | Severe Thunderstorm Warning | BYZ | Carter | 31 min |
| Jul 21, 5:40 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence, Pennington | 65 min |
| Jul 21, 5:44 PM MDT | Severe Thunderstorm Warning | GGW | Richland, Roosevelt | 61 min |
| Jul 21, 5:45 PM MDT | Severe Thunderstorm Warning | UNR | Crook | 42 min |
| Jul 21, 5:47 PM MDT | Severe Thunderstorm Warning | BIS | McKenzie, Williams | 58 min |
| Jul 21, 5:55 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence, Pennington | 18 min |
| Jul 21, 5:59 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence, Meade | 40 min |
| Jul 21, 6:03 PM MDT | Severe Thunderstorm Warning | UNR | Pennington | 40 min |
| Jul 21, 6:16 PM MDT | Severe Thunderstorm Warning | UNR | Custer | 39 min |
| Jul 21, 6:21 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Lawrence | 24 min |
| Jul 21, 6:29 PM MDT | Severe Thunderstorm Warning | UNR | Crook, Weston | 39 min |
| Jul 21, 6:41 PM MDT | Severe Thunderstorm Warning | BIS | McKenzie, Williams | 64 min |
| Jul 21, 6:44 PM MDT | Severe Thunderstorm Warning | BIS | Billings, Golden Valley, McKenzie | 61 min |
| Jul 21, 6:45 PM MDT | Severe Thunderstorm Warning | GGW | Richland | 30 min |
| Jul 21, 6:52 PM MDT | Severe Thunderstorm Warning | UNR | Lawrence, Meade | 37 min |
| Jul 21, 7:27 PM MDT | Severe Thunderstorm Warning | UNR | Custer | 55 min |
| Jul 21, 7:42 PM MDT | Severe Thunderstorm Warning | BIS | Burke, Divide, Williams | 24 min |
| Jul 21, 7:49 PM MDT | Severe Thunderstorm Warning | BIS | Billings, Golden Valley, McKenzie | 56 min |
| Jul 21, 8:07 PM MDT | Severe Thunderstorm Warning | UNR | 68 min | |
| Jul 21, 8:46 PM MDT | Severe Thunderstorm Warning | UNR | Custer | 17 min |
| Jul 21, 9:14 PM MDT | Severe Thunderstorm Warning | BIS | Burke, Divide | 61 min |
| Jul 21, 9:14 PM MDT | Severe Thunderstorm Warning | UNR | Bennett | 61 min |
| Jul 21, 10:02 PM MDT | Severe Thunderstorm Warning | UNR | Bennett, Jackson, Mellette, Todd | 58 min |
| Jul 21, 11:00 PM MDT | Severe Thunderstorm Warning | BIS | Burke, Renville, Ward | 30 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
Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 10.7 hours before the alert went out and 262 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
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, 4:25 PM MDT | Mesoscale Discussion | SPC | Carter, Custer, Daniels, Dawson, Fallon, Garfield and 6 more | 65 min |
| 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 |
| Jul 21, 5:12 PM MDT | Mesoscale Discussion | SPC | Albany, Goshen, Laramie, Platte | 78 min |
Nearby
Severe Thunderstorm Watches in North Dakota, 2012Severe Thunderstorm Watches in South Dakota, 2012Severe Thunderstorm Watches in Montana, 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.