Alert archive / South Dakota / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 684
The Storm Prediction Center issued this severe thunderstorm watch at Jul 25, 2011, 1:30 PM MDT for 7 counties in Montana; 15 counties in South Dakota; 4 counties in Wyoming. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 25, 2011, 1:30 PM MDT (19:30 UTC)
- Expired
- Jul 25, 2011, 9:00 PM MDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 26 counties
Big Horn County, MT, Carter County, MT, Custer County, MT, Fallon County, MT, Powder River County, MT, Rosebud County, MT, Treasure County, MT, 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, Mellette County, SD, Pennington County, SD, Perkins County, SD, Todd County, SD, Tripp County, SD, Ziebach County, SD, Campbell County, WY, Crook County, WY, Sheridan County, WY, Weston County, WY
The radar
The Rapid City radar (KUDX), 246 km from the middle of the area, began a volume at 19:31 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.
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
- 30%
- One or more hailstones of 2 inches or more
- 40%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
29 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 25, 2:28 PM MDT | Severe Thunderstorm Warning | UNR | Meade, Pennington | 62 min |
| Jul 25, 2:38 PM MDT | Severe Thunderstorm Warning | BYZ | Powder River | 52 min |
| Jul 25, 2:49 PM MDT | Severe Thunderstorm Warning | UNR | Campbell, Crook | 56 min |
| Jul 25, 3:08 PM MDT | Severe Thunderstorm Warning | UNR | Custer, Pennington | 67 min |
| Jul 25, 3:16 PM MDT | Severe Thunderstorm Warning | BYZ | Carter, Powder River | 59 min |
| Jul 25, 3:24 PM MDT | Severe Thunderstorm Warning | UNR | Meade, Pennington | 22 min |
| Jul 25, 3:25 PM MDT | Severe Thunderstorm Warning | BYZ | Powder River | 65 min |
| Jul 25, 3:59 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Lawrence | 61 min |
| Jul 25, 4:00 PM MDT | Severe Thunderstorm Warning | UNR | Meade, Pennington | 60 min |
| Jul 25, 4:07 PM MDT | Severe Thunderstorm Warning | BYZ | Carter, Powder River | 53 min |
| Jul 25, 4:13 PM MDT | Severe Thunderstorm Warning | BYZ | Custer | 62 min |
| Jul 25, 4:13 PM MDT | Severe Thunderstorm Warning | BYZ | Carter | 48 min |
| Jul 25, 4:18 PM MDT | Severe Thunderstorm Warning | UNR | Custer, Pennington | 46 min |
| Jul 25, 4:21 PM MDT | Severe Thunderstorm Warning | BYZ | Powder River | 54 min |
| Jul 25, 4:23 PM MDT | Severe Thunderstorm Warning | UNR | Harding | 67 min |
| Jul 25, 4:43 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Harding | 62 min |
| Jul 25, 4:44 PM MDT | Severe Thunderstorm Warning | UNR | Custer, Pennington | 61 min |
| Jul 25, 5:00 PM MDT | Severe Thunderstorm Warning | UNR | Haakon, Jackson, Pennington | 60 min |
| Jul 25, 5:01 PM MDT | Severe Thunderstorm Warning | BYZ | Custer, Powder River | 30 min |
| Jul 25, 5:10 PM MDT | Severe Thunderstorm Warning | UNR | Jackson, Pennington | 65 min |
| Jul 25, 5:16 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Harding, Meade, Perkins | 29 min |
| Jul 25, 5:33 PM MDT | Severe Thunderstorm Warning | UNR | Bennett, Haakon, Jackson, Pennington | 57 min |
| Jul 25, 5:38 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Harding, Meade, Perkins | 67 min |
| Jul 25, 5:52 PM MDT | Severe Thunderstorm Warning | UNR | Bennett | 53 min |
| Jul 25, 6:15 PM MDT | Severe Thunderstorm Warning | UNR | Bennett, Haakon, Jackson, Mellette, Todd, Tripp | 60 min |
| Jul 25, 6:38 PM MDT | Severe Thunderstorm Warning | UNR | Bennett, Jackson | 65 min |
| Jul 25, 6:39 PM MDT | Severe Thunderstorm Warning | UNR | Meade, Perkins, Ziebach | 66 min |
| Jul 25, 6:44 PM MDT | Flash Flood Warning | UNR | Meade, Perkins | 3 hr |
| Jul 25, 7:15 PM MDT | Severe Thunderstorm Warning | UNR | Bennett, Jackson, Mellette, Todd, Tripp | 28 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 (KUNR), launched 12:00Z, 7.5 hours before the alert went out and 247 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
- 2427 J/kg
- Mixed-layer CIN
- -88 J/kg
- Mixed-layer LCL
- 1325 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 39 m²/s²
- 0-3 km storm-relative helicity
- 17 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 25, 11:23 AM MDT | Mesoscale Discussion | SPC | Carter, Powder River | 97 min |
| Jul 25, 2:23 PM MDT | Mesoscale Discussion | SPC | Broadwater, Cascade, Chouteau, Fergus, Gallatin, Golden Valley and 10 more | 97 min |
| Jul 25, 4:39 PM MDT | Mesoscale Discussion | SPC | Carter | 96 min |
| Jul 25, 5:15 PM MDT | Mesoscale Discussion | SPC | Dawson, Garfield, McCone, Phillips, Prairie, Richland and 3 more | 2 hr |
| Jul 25, 5:47 PM MDT | Severe Thunderstorm Watch | SPC | Blaine, Chouteau, Dawson, Fergus, Garfield, Judith Basin and 8 more | 7 hr |
| Jul 25, 1:56 PM MDT | Mesoscale Discussion | SPC | Brookings, Clark, Codington, Deuel, Grant, Hamlin and 4 more | 94 min |
| Jul 25, 1:32 PM MDT | Mesoscale Discussion | SPC | Albany, Converse, Goshen, Laramie, Niobrara, Platte | 88 min |
Nearby
Severe Thunderstorm Watches in South Dakota, 2011Severe Thunderstorm Watches in Montana, 2011Severe Thunderstorm Watches in Wyoming, 2011Every severe thunderstorm watch 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.