Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 1630
The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2021, 2:43 PM CDT for 4 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 28, 2021, 2:43 PM CDT (19:43 UTC)
- Expired
- Aug 28, 2021, 5:15 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 39 counties
Lyon County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Antelope County, NE, Boone County, NE, Cedar County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Knox County, NE, Loup County, NE, Madison County, NE, Pierce County, NE, Platte County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Hanson County, SD, Hutchinson County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Moody County, SD, Turner County, SD, Union County, SD, Yankton County, SD
The radar
The Sioux Falls radar (KFSD), 127 km from the middle of the area, began a volume at 19:43 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
Omaha, NE (KOAX), launched 12:00Z, 7.7 hours before the alert went out and 177 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
- 929 J/kg
- Mixed-layer CIN
- -277 J/kg
- Mixed-layer LCL
- 1419 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- 36 m²/s²
- 0-3 km storm-relative helicity
- 98 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted.
385
ACUS11 KWNS 281943
SWOMCD
SPC MCD 281943
IAZ000-MNZ000-NEZ000-SDZ000-282215-
Mesoscale Discussion 1630
NWS Storm Prediction Center Norman OK
0243 PM CDT Sat Aug 28 2021
Areas affected...southeast South Dakota...northeast
Nebraska...western Iowa...southwest Minnesota
Concerning...Severe potential...Watch possible
Valid 281943Z - 282215Z
Probability of Watch Issuance...60 percent
SUMMARY...Storms are likely to increase along a cold front after 21
or 22Z from northeast Nebraska into southeast South Dakota. Damaging
gusts and large hail will be possible.
DISCUSSION...Destabilization continues ahead of a cold front with
MLCAPE over 2500 J/kg. Meanwhile, deep-layer shear across parts of
SD has increased to 50 kt. A few cells are noted over southeast SD,
although disorganized in nature as of 20Z.
As the upper trough approaches, wind fields will increase, aiding
severe potential. Storm should increase in coverage along the front
with the air of peak heating, mainly after 21 or 22Z. Sufficient
low-level SRH ahead of the front may support a period of supercell
potential with hail before storms eventually merge into a line with
damaging wind threat. Enhanced SRH near the IA outflow boundary and
across west-central MN could conceivably support a brief tornado
should storms remain cellular.
..Jewell/Grams.. 08/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FSD...OAX...GID...LBF...
LAT...LON 41699669 41399852 41389959 41509976 41909973 42359922
43069858 43909754 44219668 44219586 44049558 43429553
42089624 41699669SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 7:59 PM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton, Fayette | 2 hr |
| Aug 27, 9:57 PM CDT | Mesoscale Discussion | SPC | Allamakee, Bremer, Chickasaw, Clayton, Fayette, Floyd and 3 more | 93 min |
| Aug 28, 3:57 PM CDT | Severe Thunderstorm Watch | SPC | Lyon, O'Brien, Osceola, Plymouth, Sioux, Woodbury | 7 hr |
| Aug 28, 5:27 PM CDT | Mesoscale Discussion | SPC | Emmet | 63 min |
| Aug 28, 2:17 AM CDT | Mesoscale Discussion | SPC | Big Stone, Stevens, Swift, Traverse | 2 hr |
| 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, 3:44 PM CDT | Tornado Watch | SPC | Cottonwood, Jackson, Lincoln, Lyon, Murray, Nobles and 2 more | 5 hr |
| 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 Nebraska, 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.