Alert archive / Minnesota / Mesoscale Discussions in 2020
Mesoscale Discussion 1421
The Storm Prediction Center issued this mesoscale discussion at Aug 7, 2020, 11:25 PM CDT for 13 counties in Minnesota; Burnett County, Polk County, Wisconsin. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- Aug 7, 2020, 11:25 PM CDT (04:25 UTC)
- Expired
- Aug 8, 2020, 1:00 AM CDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 420
Counties Aitkin County, MN, Anoka County, MN, Benton County, MN, Carlton County, MN, Chisago County, MN, Crow Wing County, MN, Isanti County, MN, Kanabec County, MN, Mille Lacs County, MN, Morrison County, MN, Pine County, MN, Sherburne County, MN, Stearns County, MN, Burnett County, WI, Polk County, WI
The radar
The Duluth radar (KDLH), 129 km from the middle of the area, began a volume at 04:26 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
Minneapolis, MN (KMPX), launched 00:00Z, 4.4 hours before the alert went out and 141 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
- 933 J/kg
- Mixed-layer CIN
- -82 J/kg
- Mixed-layer LCL
- 1112 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 160 m²/s²
- 0-3 km storm-relative helicity
- 260 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 9.3
The text
As transmitted.
641
ACUS11 KWNS 080426
SWOMCD
SPC MCD 080425
WIZ000-MNZ000-080600-
Mesoscale Discussion 1421
NWS Storm Prediction Center Norman OK
1125 PM CDT Fri Aug 07 2020
Areas affected...east-central Minnesota and adjacent northwestern
Wisconsin
Concerning...Severe Thunderstorm Watch 420...
Valid 080425Z - 080600Z
The severe weather threat for Severe Thunderstorm Watch 420
continues.
SUMMARY...Local severe risk persists with one or two of the more
intense/remaining storms, but will continue to gradually diminish
over the next 1 to 2 hours.
DISCUSSION...Latest radar loop shows a small cluster of storms
persisting in conjunction with the continued eastward advance of a
well-defined mesoscale circulation/MCV, now approaching the
Arrowhead region of Minnesota. Instability diminishes steadily
downstream from the ongoing storms into Wisconsin and western Lake
Superior, which suggests a continued decrease in convective
intensity. The strongest storms remain now on the southern and
southwestern flanks of the MCV circulation, where greater
instability is combining with a southwesterly low-level-jet-induced
zone of warm advection to yield this favored zone of persistent
convective redevelopment.
With that said, as the system shifts eastward with time, and capping
continues to increase with respect to surface-based parcels, storms
will continue to weaken and trend toward becoming more elevated.
This suggests that the notable decrease in convective intensity
which has occurred over the past hour will continue, and should
preclude any need for a new WW beyond the scheduled 06Z expiration
of WW 420.
..Goss.. 08/08/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DLH...MPX...FGF...
LAT...LON 46909410 46739196 45469206 45159304 45309468 46399482
46909410SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 7, 8:02 PM CDT | Mesoscale Discussion | SPC | Aitkin, Becker, Benton, Carlton, Cass, Chisago and 10 more | 118 min |
| Aug 8, 12:06 PM CDT | Mesoscale Discussion | SPC | Becker, Big Stone, Cass, Chippewa, Crow Wing, Douglas and 11 more | 114 min |
| Aug 8, 1:26 PM CDT | Mesoscale Discussion | SPC | Blue Earth, Brown, Carver, Chippewa, Cottonwood, Le Sueur and 7 more | 94 min |
| Aug 8, 5:00 PM CDT | Mesoscale Discussion | SPC | Dakota, Dodge, Fillmore, Freeborn, Goodhue, Houston and 9 more | 2 hr |
Nearby
Mesoscale Discussions in Minnesota, 2020Mesoscale Discussions in Wisconsin, 2020Every mesoscale discussion in 2020
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.