Alert archive / South Dakota / Severe Thunderstorm Watches in 2020
Severe Thunderstorm Watch 461
The Storm Prediction Center issued this severe thunderstorm watch at Aug 27, 2020, 10:20 PM CDT for 4 counties in North Dakota; 42 counties in South Dakota. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 27, 2020, 10:20 PM CDT (03:20 UTC)
- Expired
- Aug 28, 2020, 2:58 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 70 kt
All 46 counties
Dickey County, ND, Emmons County, ND, McIntosh County, ND, Sargent County, ND, Aurora County, SD, Beadle County, SD, Brookings County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Campbell County, SD, Charles Mix County, SD, Clark County, SD, Codington County, SD, Davison County, SD, Day County, SD, Deuel County, SD, Douglas County, SD, Edmunds County, SD, Faulk County, SD, Grant County, SD, Gregory County, SD, Hamlin County, SD, Hand County, SD, Hanson County, SD, Hughes County, SD, Hutchinson County, SD, Hyde County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, Lyman County, SD, Marshall County, SD, McCook County, SD, McPherson County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Potter County, SD, Roberts County, SD, Sanborn County, SD, Spink County, SD, Sully County, SD, Turner County, SD, Walworth County, SD
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
- 10%
- Ten or more severe wind reports
- 70%
- One or more gusts of 65 knots or more
- 50%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
16 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 10:54 PM CDT | Severe Thunderstorm Warning | ABR | Dewey, Jones, Stanley, Sully | 36 min |
| Aug 27, 11:12 PM CDT | Severe Thunderstorm Warning | ABR | Hughes, Hyde, Jones, Lyman, Stanley, Sully | 48 min |
| Aug 27, 11:42 PM CDT | Severe Thunderstorm Warning | ABR | Buffalo, Hand, Hughes, Hyde, Stanley, Sully | 78 min |
| Aug 28, 12:27 AM CDT | Severe Thunderstorm Warning | FSD | Beadle, Jerauld, Sanborn | 63 min |
| Aug 28, 1:02 AM CDT | Severe Thunderstorm Warning | FSD | Beadle, Sanborn | 28 min |
| Aug 28, 1:05 AM CDT | Severe Thunderstorm Warning | FSD | Aurora, Brule, Davison, Sanborn | 25 min |
| Aug 28, 1:09 AM CDT | Severe Thunderstorm Warning | FSD | Brookings, Kingsbury, Lake, Miner | 66 min |
| Aug 28, 1:11 AM CDT | Severe Thunderstorm Warning | ABR | Clark, Codington, Day, Hamlin, Spink | 49 min |
| Aug 28, 1:19 AM CDT | Tornado Warning | FSD | Kingsbury | 26 min |
| Aug 28, 1:22 AM CDT | Tornado Warning | FSD | Kingsbury | 38 min |
| Aug 28, 1:28 AM CDT | Severe Thunderstorm Warning | FSD | Hanson, McCook | 62 min |
| Aug 28, 1:49 AM CDT | Severe Thunderstorm Warning | ABR | Codington, Deuel, Hamlin | 56 min |
| Aug 28, 1:50 AM CDT | Tornado Warning | FSD | Brookings, Kingsbury | 25 min |
| Aug 28, 2:01 AM CDT | Severe Thunderstorm Warning | FSD | Brookings, Lake, Moody | 59 min |
| Aug 28, 2:15 AM CDT | Tornado Warning | FSD | Brookings | 30 min |
| Aug 28, 2:20 AM CDT | Tornado Warning | ABR | Deuel | 13 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 00:00Z, 3.3 hours before the alert went out and 33 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
- 451 J/kg
- Mixed-layer CIN
- -200 J/kg
- Mixed-layer LCL
- 1389 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 140 m²/s²
- 0-3 km storm-relative helicity
- 218 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 27, 9:20 PM CDT | Mesoscale Discussion | SPC | Adams, Bowman, Grant, Hettinger, Sioux, Slope | 85 min |
| Aug 27, 11:30 PM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Brookings, Brule, Buffalo, Charles Mix and 24 more | 2 hr |
| Aug 28, 1:28 AM CDT | Mesoscale Discussion | SPC | Deuel, Moody | 92 min |
Nearby
Severe Thunderstorm Watches in South Dakota, 2020Severe Thunderstorm Watches in North Dakota, 2020Every severe thunderstorm watch in 2020
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.