Alert archive / South Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 1603
The Storm Prediction Center issued this mesoscale discussion at Aug 26, 2021, 1:35 AM MDT for 6 counties in North Dakota; 12 counties in South Dakota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 26, 2021, 1:35 AM MDT (07:35 UTC)
- Expired
- Aug 26, 2021, 4:00 AM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Adams County, ND, Dickey County, ND, Emmons County, ND, Grant County, ND, McIntosh County, ND, Sioux County, ND, Brown County, SD, Campbell County, SD, Corson County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Harding County, SD, McPherson County, SD, Perkins County, SD, Potter County, SD, Walworth County, SD, Ziebach County, SD
The radar
The Bismarck radar (KBIS), 134 km from the middle of the area, began a volume at 07:38 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
Bismarck Municip, ND (KBIS), launched 00:00Z, 7.6 hours before the alert went out and 136 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
- 2183 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 24 m²/s²
- 0-3 km storm-relative helicity
- 281 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
098
ACUS11 KWNS 260736
SWOMCD
SPC MCD 260735
SDZ000-NDZ000-261000-
Mesoscale Discussion 1603
NWS Storm Prediction Center Norman OK
0235 AM CDT Thu Aug 26 2021
Areas affected...Portions of southern ND and northern SD
Concerning...Severe potential...Watch unlikely
Valid 260735Z - 261000Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated large hail may occur with elevated storms early
this morning. Watch issuance appears unlikely.
DISCUSSION...Water vapor satellite imagery shows a mid-level impulse
ejecting from the northern Rockies across the adjacent Plains early
this morning. A 25-35 kt southerly low-level jet centered over SD is
also providing lift, and storms along the ND/SD border have recently
increased in coverage and intensity. An MUCAPE gradient exists
along/near the ND/SD border in association with returning low-level
moisture centered around 850 mb. About 2000-2500 J/kg of MUCAPE
should be available for this convection as it moves generally
eastward, with storms likely remaining elevated given greater
surface dewpoints remain displaced well to the south across NE.
Still, effective bulk shear of 40-50 kt will prove favorable for
supercells with an associated threat for isolated large hail given
the steep mid-level lapse rates present across much of the northern
Plains. Current expectations are for this hail threat to remain
fairly isolated through the early morning, and a watch appears
unlikely. There may also be a tendency for these supercells to form
into a cluster or two, and a sporadic strong wind gust breaching the
near-surface stable layer may also occur.
..Gleason/Thompson.. 08/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ABR...BIS...UNR...
LAT...LON 45500390 46230301 46540217 46390029 46219816 45229812
44859933 44870165 45130337 45500390SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 26, 2:10 AM MDT | Mesoscale Discussion | SPC | Bon Homme, Charles Mix, Clay, Hutchinson, Turner, Yankton | 3 hr |
| Aug 26, 7:36 AM MDT | Mesoscale Discussion | SPC | Beadle, Brookings, Buffalo, Clark, Codington, Day and 10 more | 84 min |
| Aug 26, 8:05 AM MDT | Severe Thunderstorm Watch | SPC | Beadle, Brookings, Clark, Codington, Deuel, Grant and 7 more | 4 hr |
| Aug 26, 9:43 AM MDT | Mesoscale Discussion | SPC | Brookings, Deuel, Moody | 92 min |
| Aug 26, 4:34 PM MDT | Mesoscale Discussion | SPC | Clay, Lincoln, Turner, Union, Yankton | 116 min |
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.