Alert archive / South Dakota / Severe Thunderstorm Watches in 2007
Severe Thunderstorm Watch 283
The Storm Prediction Center issued this severe thunderstorm watch at May 21, 2007, 1:52 PM MDT for 24 counties in South Dakota; Crook County, Weston County, Wyoming. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- May 21, 2007, 1:52 PM MDT (19:52 UTC)
- Expired
- May 21, 2007, 10:00 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
Bennett County, SD, Butte County, SD, Campbell County, SD, Corson County, SD, Custer County, SD, Dewey County, SD, Fall River County, SD, Haakon County, SD, Harding County, SD, Hughes County, SD, Jackson County, SD, Jones County, SD, Lawrence County, SD, Lyman County, SD, Meade County, SD, Mellette County, SD, Pennington County, SD, Perkins County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Walworth County, SD, Ziebach County, SD, Crook County, WY, Weston County, WY
The radar
The Rapid City radar (KUDX), 73 km from the middle of the area, began a volume at 19:55 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
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 60%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 3:34 PM MDT | Severe Thunderstorm Warning | UNR | Butte, Lawrence | 56 min |
| May 21, 3:52 PM MDT | Severe Thunderstorm Warning | UNR | Meade | 53 min |
| May 21, 4:33 PM MDT | Severe Thunderstorm Warning | UNR | Butte | 39 min |
| May 21, 4:40 PM MDT | Severe Thunderstorm Warning | UNR | Meade | 65 min |
| May 21, 4:46 PM MDT | Severe Thunderstorm Warning | UNR | 59 min | |
| May 21, 5:03 PM MDT | Severe Thunderstorm Warning | UNR | Weston | 60 min |
| May 21, 5:09 PM MDT | Severe Thunderstorm Warning | UNR | Custer, Pennington | 66 min |
| May 21, 5:40 PM MDT | Severe Thunderstorm Warning | UNR | Meade | 65 min |
| May 21, 6:10 PM MDT | Severe Thunderstorm Warning | UNR | Butte | 32 min |
| May 21, 6:14 PM MDT | Severe Thunderstorm Warning | UNR | Pennington | 36 min |
| May 21, 6:18 PM MDT | Severe Thunderstorm Warning | ABR | Dewey | 57 min |
| May 21, 6:54 PM MDT | Severe Thunderstorm Warning | ABR | Corson | 66 min |
| May 21, 7:07 PM MDT | Severe Thunderstorm Warning | UNR | Perkins | 23 min |
| May 21, 7:08 PM MDT | Severe Thunderstorm Warning | UNR | Ziebach | 54 min |
| May 21, 7:23 PM MDT | Severe Thunderstorm Warning | ABR | Corson, Dewey | 13 min |
| May 21, 7:27 PM MDT | Severe Thunderstorm Warning | ABR | Corson | 63 min |
| May 21, 8:22 PM MDT | Severe Thunderstorm Warning | ABR | Corson | 23 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, 7.9 hours before the alert went out and 80 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
- 222 J/kg
- Mixed-layer CIN
- -453 J/kg
- Mixed-layer LCL
- 1556 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 186 m²/s²
- 0-3 km storm-relative helicity
- 193 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 |
|---|---|---|---|---|
| May 20, 6:48 PM MDT | Mesoscale Discussion | SPC | Butte, Lawrence | 87 min |
| May 21, 12:07 PM MDT | Mesoscale Discussion | SPC | Roberts | 83 min |
| May 21, 1:34 PM MDT | Mesoscale Discussion | SPC | Campbell, Corson, Dewey, Haakon, Hughes, Jackson and 13 more | 86 min |
| May 21, 5:17 PM MDT | Mesoscale Discussion | SPC | Butte, Campbell, Corson, Custer, Dewey, Haakon and 9 more | 88 min |
Nearby
Severe Thunderstorm Watches in South Dakota, 2007Severe Thunderstorm Watches in Wyoming, 2007Every severe thunderstorm watch in 2007
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.