Alert archive / South Dakota / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 256
The Storm Prediction Center issued this severe thunderstorm watch at Jun 11, 2021, 2:15 AM CDT for 40 counties in South Dakota. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 11, 2021, 2:15 AM CDT (07:15 UTC)
- Expired
- Jun 11, 2021, 7:00 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 40 counties
Aurora County, SD, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Clark County, SD, Clay 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, Hutchinson County, SD, Hyde County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, Marshall County, SD, McCook County, SD, McPherson County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Roberts County, SD, Sanborn County, SD, Spink County, SD, Turner County, SD, Union County, SD, Yankton County, SD
The radar
The Aberdeen radar (KABR), 84 km from the middle of the area, began a volume at 07:16 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
- 40%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
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 |
|---|---|---|---|---|
| Jun 11, 2:37 AM CDT | Severe Thunderstorm Warning | ABR | Edmunds, Faulk, McPherson, Potter, Walworth | 38 min |
| Jun 11, 2:54 AM CDT | Severe Thunderstorm Warning | ABR | Faulk, Potter, Sully | 36 min |
| Jun 11, 3:13 AM CDT | Severe Thunderstorm Warning | FSD | Brule, Charles Mix, Gregory | 47 min |
| Jun 11, 3:16 AM CDT | Severe Thunderstorm Warning | ABR | Campbell, Edmunds, Faulk, McPherson, Potter, Walworth | 44 min |
| Jun 11, 3:23 AM CDT | Severe Thunderstorm Warning | ABR | Buffalo, Hand, Spink | 52 min |
| Jun 11, 3:26 AM CDT | Severe Thunderstorm Warning | FSD | Beadle, Jerauld | 64 min |
| Jun 11, 3:38 AM CDT | Severe Thunderstorm Warning | ABR | Brown, Day, Edmunds, Faulk, McPherson, Marshall and 1 more | 52 min |
| Jun 11, 3:39 AM CDT | Severe Thunderstorm Warning | FSD | Aurora, Charles Mix, Douglas, Gregory | 51 min |
| Jun 11, 4:16 AM CDT | Severe Thunderstorm Warning | ABR | Brown, Clark, Codington, Day, Grant, Marshall and 2 more | 44 min |
| Jun 11, 4:49 AM CDT | Severe Thunderstorm Warning | ABR | Clark, Codington, Grant, Hamlin, Spink | 41 min |
| Jun 11, 4:59 AM CDT | Severe Thunderstorm Warning | FSD | Bon Homme, Charles Mix | 46 min |
| Jun 11, 5:02 AM CDT | Severe Thunderstorm Warning | ABR | Clark, Codington, Day, Deuel, Grant, Marshall and 1 more | 43 min |
| Jun 11, 5:04 AM CDT | Severe Thunderstorm Warning | FSD | Brookings, Kingsbury, Lake, Miner | 41 min |
| Jun 11, 5:35 AM CDT | Severe Thunderstorm Warning | ABR | Codington, Deuel, Hamlin | 40 min |
| Jun 11, 5:41 AM CDT | Severe Thunderstorm Warning | FSD | Yankton | 34 min |
| Jun 11, 5:49 AM CDT | Severe Thunderstorm Warning | ABR | Codington, Deuel, Grant, Roberts | 33 min |
| Jun 11, 5:56 AM CDT | Severe Thunderstorm Warning | FSD | Clay, Union | 49 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, 7.3 hours before the alert went out and 36 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
- 1337 J/kg
- Mixed-layer CIN
- -37 J/kg
- Mixed-layer LCL
- 2725 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 42 m²/s²
- 0-3 km storm-relative helicity
- 91 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.7
The text
As transmitted.
748 WWUS20 KWNS 110712 SEL6 SPC WW 110712 NEZ000-SDZ000-111200- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 256 NWS Storm Prediction Center Norman OK 215 AM CDT Fri Jun 11 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Extreme northeastern Nebraska Eastern South Dakota * Effective this Friday morning from 215 AM until 700 AM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...A squall line across central South Dakota will move eastward through the early morning hours. Occasional damaging gusts and isolated, marginally severe hail will be possible with the stronger storms in the line. The severe threat should diminish before sunrise, except for areas near the Missouri River in extreme southeast South Dakota and northeast Nebraska. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 35 miles north of Aberdeen SD to 55 miles south of Mitchell SD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 253...WW 254...WW 255... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27030. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 10, 8:28 PM CDT | Mesoscale Discussion | SPC | Bennett, Butte, Corson, Custer, Dewey, Fall River and 17 more | 92 min |
| Jun 10, 9:08 PM CDT | Severe Thunderstorm Watch | SPC | Bennett, Butte, Campbell, Corson, Custer, Dewey and 20 more | 6 hr |
| Jun 10, 11:07 PM CDT | Mesoscale Discussion | SPC | Bennett, Butte, Corson, Custer, Dewey, Fall River and 8 more | 83 min |
| Jun 10, 11:50 PM CDT | Mesoscale Discussion | SPC | Dewey, Haakon, Jackson, Jones, Meade, Mellette and 5 more | 85 min |
| Jun 11, 12:52 AM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Bon Homme, Brookings, Brown, Brule and 35 more | 53 min |
| Jun 11, 4:37 AM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Brookings, Brown, Charles Mix, Clark and 21 more | 83 min |
Nearby
Severe Thunderstorm Watches in South Dakota, 2021Every severe thunderstorm watch in 2021
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.