Alert archive / Minnesota / Mesoscale Discussions in 2021
Mesoscale Discussion 1761
The Storm Prediction Center issued this mesoscale discussion at Sep 16, 2021, 6:23 PM CDT for 5 counties in Iowa; 19 counties in Minnesota; 6 counties in South Dakota. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Sep 16, 2021, 6:23 PM CDT (23:23 UTC)
- Expired
- Sep 16, 2021, 8:00 PM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 30 counties
Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Sioux County, IA, Chippewa County, MN, Cottonwood County, MN, Jackson County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Lincoln County, MN, Lyon County, MN, Meeker County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Pope County, MN, Redwood County, MN, Renville County, MN, Rock County, MN, Stearns County, MN, Stevens County, MN, Swift County, MN, Yellow Medicine County, MN, Brookings County, SD, Clay County, SD, Lincoln County, SD, Minnehaha County, SD, Moody County, SD, Turner County, SD
The radar
The Sioux Falls radar (KFSD), 99 km from the middle of the area, began a volume at 23:23 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
Minneapolis, MN (KMPX), launched 12:00Z, 11.4 hours before the alert went out and 190 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
- 1213 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 362 m²/s²
- 0-3 km storm-relative helicity
- 428 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.0
The text
As transmitted.
774
ACUS11 KWNS 162324
SWOMCD
SPC MCD 162323
MNZ000-IAZ000-SDZ000-170100-
Mesoscale Discussion 1761
NWS Storm Prediction Center Norman OK
0623 PM CDT Thu Sep 16 2021
Areas affected...Eastern South Dakota...Southwest and Central
Minnesota...Far Northwest Iowa
Concerning...Severe potential...Watch likely
Valid 162323Z - 170100Z
Probability of Watch Issuance...80 percent
SUMMARY...A severe threat is expected to develop from central
Minnesota southwestward into far southeastern South Dakota. Large
hail and wind damage will be the primary threats. Weather watch
issuance will likely be needed across the region early this evening.
DISCUSSION...Latest surface analysis shows a cold front moving
southeastward across west-central Minnesota and southeastern South
Dakota. A moist airmass is located ahead of the front with surface
dewpoints generally in the lower to mid 60s F. This is contributing
to a narrow corridor of moderate instability where the RAP is
estimating MLCAPE in the 2000 to 2500 J/kg range. This combined with
increasing low-level convergence just ahead of the front will
support continued thunderstorm development this evening. In addition
to the instability, RAP forecast soundings early this evening across
southwest Minnesota have veering winds with height in the low levels
with about 50 kt of west-southwest flow at 500 mb. This is helping
to create 0-6 km shear near 40 kt, which will likely support severe
thunderstorm development over the next few hours as cells gradually
increase in coverage. Although supercells with large hail will be
possible, the stronger line segments may also be able to produce
wind damage as well.
..Broyles/Edwards.. 09/16/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MPX...FSD...ABR...
LAT...LON 43189516 42909573 42879646 42909712 43109732 43569737
44239699 45569611 45939531 45889478 45659442 45059446
44469479 43189516SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 16, 3:47 PM CDT | Mesoscale Discussion | SPC | Aitkin, Anoka, Benton, Carlton, Carver, Cass and 25 more | 118 min |
| Sep 16, 5:57 PM CDT | Tornado Watch | SPC | Aitkin, Carlton, Crow Wing, Kanabec, Lake, Mille Lacs and 4 more | 4 hr |
| Sep 16, 6:39 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Brown, Chippewa, Cottonwood, Isanti, Kandiyohi and 14 more | 4 hr |
Nearby
Mesoscale Discussions in Minnesota, 2021Mesoscale Discussions in South Dakota, 2021Mesoscale Discussions in Iowa, 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.