Alert archive / South Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 1585
The Storm Prediction Center issued this mesoscale discussion at Aug 23, 2021, 11:32 PM CDT for 5 counties in North Dakota; 14 counties in South Dakota. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Aug 23, 2021, 11:32 PM CDT (04:32 UTC)
- Expired
- Aug 24, 2021, 1:30 AM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 459
Counties Dickey County, ND, Emmons County, ND, McIntosh County, ND, Richland County, ND, Sargent County, ND, Brown County, SD, Campbell County, SD, Clark County, SD, Codington County, SD, Day County, SD, Edmunds County, SD, Faulk County, SD, Hamlin County, SD, Marshall County, SD, McPherson County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Walworth County, SD
The radar
The Aberdeen radar (KABR), 62 km from the middle of the area, began a volume at 04:33 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.
The nearest sounding before it
Aberdeen, SD (KABR), launched 00:00Z, 4.5 hours before the alert went out and 83 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
- 142 J/kg
- Mixed-layer CIN
- -222 J/kg
- Mixed-layer LCL
- 2124 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- 173 m²/s²
- 0-3 km storm-relative helicity
- 342 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted.
681 ACUS11 KWNS 240432 SWOMCD SPC MCD 240432 MNZ000-SDZ000-NDZ000-240630- Mesoscale Discussion 1585 NWS Storm Prediction Center Norman OK 1132 PM CDT Mon Aug 23 2021 Areas affected...Dakotas Concerning...Severe Thunderstorm Watch 459... Valid 240432Z - 240630Z The severe weather threat for Severe Thunderstorm Watch 459 continues. SUMMARY...Scattered severe thunderstorms will propagate east along the ND/SD border region tonight. Hail/wind are possible with this activity. DISCUSSION...Water-vapor imagery suggests at least one weak disturbance is ejecting northeast across the Black Hills region toward the central Dakotas. This feature appears to be partly responsible for recent upscale growth in convection over western parts of ww459. Latest radar imagery suggests significant hail core may be noted with the supercell over northwestern Potter County SD, with other strong/severe storms spreading along the ND/SD border. This activity is propagating east at roughly 25kt and should continue for several hours as substantial southerly LLJ is currently feeding this convection. ..Darrow.. 08/24/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 44750079 46510079 46329681 44599683 44750079
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 23, 7:38 PM CDT | Mesoscale Discussion | SPC | Emmons, Grant, Logan, McIntosh, Sioux | 2 hr |
| Aug 23, 9:37 PM CDT | Mesoscale Discussion | SPC | Sioux | 113 min |
| Aug 23, 10:11 PM CDT | Severe Thunderstorm Watch | SPC | Dickey, Emmons, LaMoure, Logan, McIntosh, Ransom and 3 more | 5 hr |
Nearby
Mesoscale Discussions in South Dakota, 2021Mesoscale Discussions in North Dakota, 2021Every mesoscale discussion 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.