Alert archive / South Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 1207
The Storm Prediction Center issued this mesoscale discussion at Jul 8, 2021, 8:54 PM CDT for 22 counties in South Dakota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 8, 2021, 8:54 PM CDT (01:54 UTC)
- Expired
- Jul 8, 2021, 11:00 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 354
All 22 counties
Aurora County, SD, Beadle County, SD, Brule County, SD, Buffalo County, SD, Campbell County, SD, Corson County, SD, Davison County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jerauld County, SD, Lyman County, SD, Potter County, SD, Sanborn County, SD, Spink County, SD, Stanley County, SD, Sully County, SD, Walworth County, SD, Ziebach County, SD
The radar
The Aberdeen radar (KABR), 133 km from the middle of the area, began a volume at 01:58 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, 1.9 hours before the alert went out and 111 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
- 82 J/kg
- Mixed-layer CIN
- -125 J/kg
- Mixed-layer LCL
- 996 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 133 m²/s²
- 0-3 km storm-relative helicity
- 211 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.0
The text
As transmitted.
674
ACUS11 KWNS 090155
SWOMCD
SPC MCD 090154
SDZ000-090400-
Mesoscale Discussion 1207
NWS Storm Prediction Center Norman OK
0854 PM CDT Thu Jul 08 2021
Areas affected...Central and Southeast South Dakota
Concerning...Severe Thunderstorm Watch 354...
Valid 090154Z - 090400Z
The severe weather threat for Severe Thunderstorm Watch 354
continues.
SUMMARY...A severe threat is expected to develop across central and
southeastern South Dakota over the next few hours. Large hail and
wind damage will be possible with the stronger cells. The area
affected will be to the east of WW 354, where a new watch will
likely be needed later this evening.
DISCUSSION...The latest high resolution radar from Bismark, North
Dakota shows a small cluster of severe thunderstorms centered about
100 statute miles to the west of Mobridge, South Dakota. These
storms are expected to move along the far eastern edge of WW 354.
Additional thunderstorms will develop to the east of WW 354 in parts
of central South Dakota over the next hour. According to the RAP,
the environment is characterized to have moderate instability and
strong deep-layer shear. 0-6 km shear is estimated to be as strong
as 60 kt in some areas. In addition, a band of large-scale ascent
will approach from the west, which combined with increasing lift
associated with a strengthening low-level jet, will result in
scattered thunderstorm development across central and southeastern
South Dakota later this evening. The stronger cells will likely have
a threat for large hail and wind damage. Although the convective
cluster will become elevated, it may affect areas to the east of the
Missouri River, where a new weather watch will likely be needed.
..Broyles/Thompson.. 07/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...ABR...UNR...
LAT...LON 44869775 43839768 43289859 44340107 44790181 45350184
45790158 45850011 44869775SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 8, 7:08 PM CDT | Mesoscale Discussion | SPC | Bennett, Haakon, Jackson, Meade, Oglala Lakota, Pennington and 2 more | 97 min |
| Jul 8, 9:33 PM CDT | Severe Thunderstorm Watch | SPC | Aurora, Beadle, Bon Homme, Brule, Buffalo, Charles Mix and 24 more | 5 hr |
| Jul 9, 2:41 AM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Bon Homme, Brule, Buffalo, Charles Mix and 27 more | 34 min |
| Jul 9, 6:33 PM CDT | Severe Thunderstorm Watch | SPC | Custer, Fall River, Lawrence, Oglala Lakota, Pennington | 4 hr |
Nearby
Mesoscale Discussions in South 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.