Alert archive / South Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 1625
The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2021, 2:17 AM CDT for 4 counties in Minnesota; 7 counties in South Dakota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 28, 2021, 2:17 AM CDT (07:17 UTC)
- Expired
- Aug 28, 2021, 4:45 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
Counties Big Stone County, MN, Stevens County, MN, Swift County, MN, Traverse County, MN, Brown County, SD, Day County, SD, Edmunds County, SD, Grant County, SD, Marshall County, SD, McPherson County, SD, Roberts County, SD
The radar
The Aberdeen radar (KABR), 41 km from the middle of the area, began a volume at 07:19 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Aberdeen, SD (KABR), launched 00:00Z, 7.3 hours before the alert went out and 74 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
- 650 J/kg
- Mixed-layer CIN
- -128 J/kg
- Mixed-layer LCL
- 1212 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 74 m²/s²
- 0-3 km storm-relative helicity
- 186 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 4.1
The text
As transmitted.
591
ACUS11 KWNS 280718
SWOMCD
SPC MCD 280717
MNZ000-SDZ000-NDZ000-280945-
Mesoscale Discussion 1625
NWS Storm Prediction Center Norman OK
0217 AM CDT Sat Aug 28 2021
Areas affected...Northeast South Dakota...West-central Minnesota
Concerning...Severe potential...Watch possible
Valid 280717Z - 280945Z
Probability of Watch Issuance...60 percent
SUMMARY...An isolated severe threat is expected across northeastern
South Dakota over the next few hours. Hail and strong wind gusts
will be the primary threats. The potential for severe could impact
parts of west-central Minnesota later tonight. Weather watch
issuance remains a possibility.
DISCUSSION...The latest radar imagery from Aberdeen shows a small
cluster of storms over north-central South Dakota. This cluster will
move eastward into increasing instability across northeast South
Dakota over the next couple of hours. The RAP has MLCAPE across
northeast South Dakota in the 1500 to 2500 J/kg range with effective
shear in the 50 to 60 kt range. This should be favorable for
isolated supercells with hail. A sharp temperature inversion exists
in the boundary layer which will keep the storms elevated. Although
this will temper the wind-damage threat, a few strong wind gusts can
still not be ruled out. The severe threat may impact west-central
Minnesota later tonight as the convective cluster remains intact.
..Broyles/Thompson.. 08/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MPX...FGF...ABR...BIS...
LAT...LON 45199559 44989690 45019855 45069910 45179969 45529989
45839951 45959894 45969806 45909713 45789576 45199559SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 9:57 PM CDT | Mesoscale Discussion | SPC | Fillmore, Houston | 93 min |
| Aug 28, 2:32 AM CDT | Severe Thunderstorm Watch | SPC | Big Stone, Traverse | 5 hr |
| Aug 28, 5:42 AM CDT | Mesoscale Discussion | SPC | Benton, Big Stone, Chippewa, Douglas, Grant, Kandiyohi and 11 more | 2 hr |
| Aug 28, 7:08 AM CDT | Severe Thunderstorm Watch | SPC | Big Stone, Chippewa, Douglas, Grant, Kandiyohi, Lac qui Parle and 13 more | 5 hr |
| Aug 28, 9:39 AM CDT | Mesoscale Discussion | SPC | Anoka, Benton, Chisago, Douglas, Grant, Isanti and 12 more | 2 hr |
| Aug 28, 10:34 AM CDT | Tornado Watch | SPC | Aitkin, Anoka, Benton, Carlton, Carver, Chisago and 14 more | 4 hr |
| Aug 28, 1:13 PM CDT | Mesoscale Discussion | SPC | Anoka, Chisago, Isanti, Kanabec, Pine | 2 hr |
| Aug 28, 2:43 PM CDT | Mesoscale Discussion | SPC | Murray, Nobles, Pipestone, Rock | 3 hr |
| Aug 28, 3:44 PM CDT | Tornado Watch | SPC | Cottonwood, Jackson, Lincoln, Lyon, Murray, Nobles and 2 more | 5 hr |
| Aug 28, 3:57 PM CDT | Severe Thunderstorm Watch | SPC | Cottonwood, Jackson, Murray, Nobles, Rock | 7 hr |
| Aug 28, 5:27 PM CDT | Mesoscale Discussion | SPC | Blue Earth, Brown, Carver, Cottonwood, Dakota, Dodge and 22 more | 63 min |
| Aug 28, 5:59 PM CDT | Severe Thunderstorm Watch | SPC | Blue Earth, Brown, Carver, Faribault, Freeborn, Le Sueur and 11 more | 6 hr |
| Aug 28, 6:09 PM CDT | Mesoscale Discussion | SPC | Blue Earth, Brown, Cottonwood, Nicollet, Watonwan | 66 min |
Nearby
Mesoscale Discussions in South Dakota, 2021Mesoscale Discussions in Minnesota, 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.