Alert archive / South Dakota / Severe Thunderstorm Watches in 2017
Severe Thunderstorm Watch 459
The Storm Prediction Center issued this severe thunderstorm watch at Aug 21, 2017, 8:55 AM CDT for 14 counties in South Dakota. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 21, 2017, 8:55 AM CDT (13:55 UTC)
- Expired
- Aug 21, 2017, 1:31 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
Counties Aurora County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Sanborn County, SD, Todd County, SD, Tripp County, SD
The radar
The North Platte radar (KLNX), 209 km from the middle of the area, began a volume at 13:58 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
- 5%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
14 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 8:55 AM CDT | Severe Thunderstorm Warning | ABR | Hughes, Lyman, Stanley | 65 min |
| Aug 21, 9:07 AM CDT | Severe Thunderstorm Warning | ABR | Jones | 38 min |
| Aug 21, 9:19 AM CDT | Severe Thunderstorm Warning | ABR | Jones, Lyman | 41 min |
| Aug 21, 9:42 AM CDT | Severe Thunderstorm Warning | ABR | Jones, Lyman | 33 min |
| Aug 21, 9:42 AM CDT | Severe Thunderstorm Warning | UNR | Mellette, Tripp | 63 min |
| Aug 21, 9:50 AM CDT | Severe Thunderstorm Warning | ABR | Lyman | 40 min |
| Aug 21, 10:11 AM CDT | Flash Flood Warning | ABR | Hughes, Lyman, Stanley | 3 hr |
| Aug 21, 10:16 AM CDT | Severe Thunderstorm Warning | ABR | Lyman | 30 min |
| Aug 21, 10:29 AM CDT | Severe Thunderstorm Warning | ABR | Lyman | 46 min |
| Aug 21, 10:39 AM CDT | Severe Thunderstorm Warning | FSD | Brule, Charles Mix, Gregory | 51 min |
| Aug 21, 10:42 AM CDT | Severe Thunderstorm Warning | ABR | Lyman | 33 min |
| Aug 21, 11:23 AM CDT | Severe Thunderstorm Warning | FSD | Aurora, Brule, Charles Mix, Douglas, Gregory | 52 min |
| Aug 21, 12:05 PM CDT | Severe Thunderstorm Warning | FSD | Aurora, Charles Mix, Davison, Douglas, Gregory, Hutchinson | 40 min |
| Aug 21, 12:33 PM CDT | Severe Thunderstorm Warning | FSD | Bon Homme, Davison, Douglas, Hanson, Hutchinson, Yankton | 42 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
Aberdeen, SD (KABR), launched 12:00Z, 1.9 hours before the alert went out and 173 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
- 1701 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 16 m²/s²
- 0-3 km storm-relative helicity
- 21 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 |
|---|---|---|---|---|
| Aug 20, 11:14 PM CDT | Mesoscale Discussion | SPC | Burt, Cedar, Cuming, Dakota, Dixon, Pierce and 3 more | 91 min |
| Aug 21, 11:12 AM CDT | Mesoscale Discussion | SPC | Boyd, Cedar, Dakota, Dixon, Knox | 93 min |
| Aug 21, 11:33 AM CDT | Severe Thunderstorm Watch | SPC | Antelope, Boyd, Burt, Cedar, Cuming, Dakota and 10 more | 7 hr |
| Aug 21, 2:35 PM CDT | Mesoscale Discussion | SPC | Antelope, Boone, Burt, Cedar, Cuming, Dakota and 8 more | 85 min |
| Aug 21, 5:31 AM CDT | Mesoscale Discussion | SPC | Hand, Hughes, Hyde, Potter, Stanley, Sully | 89 min |
| Aug 21, 8:27 AM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Brule, Buffalo, Charles Mix, Davison and 16 more | 2 hr |
Nearby
Severe Thunderstorm Watches in South Dakota, 2017Every severe thunderstorm watch in 2017
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.