Alert archive / Minnesota / Mesoscale Discussions in 2021
Mesoscale Discussion 1378
The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2021, 5:09 PM CDT for 13 counties in Minnesota; 11 counties in Wisconsin. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 28, 2021, 5:09 PM CDT (22:09 UTC)
- Expired
- Jul 28, 2021, 7:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...tornado watch likely
- Chance of a watch
- 95%
All 24 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, Pine County, MN, Ramsey County, MN, Sherburne County, MN, Washington County, MN, Barron County, WI, Bayfield County, WI, Burnett County, WI, Chippewa County, WI, Douglas County, WI, Dunn County, WI, Polk County, WI, Rusk County, WI, Saint Croix County, WI, Sawyer County, WI, Washburn County, WI
The radar
The Duluth radar (KDLH), 94 km from the middle of the area, began a volume at 22:12 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, 10.2 hours before the alert went out and 167 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
- 1458 J/kg
- Mixed-layer CIN
- -205 J/kg
- Mixed-layer LCL
- 1435 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 1 m²/s²
- 0-3 km storm-relative helicity
- 154 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
The text
As transmitted.
354
ACUS11 KWNS 282209
SWOMCD
SPC MCD 282209
WIZ000-MNZ000-290015-
Mesoscale Discussion 1378
NWS Storm Prediction Center Norman OK
0509 PM CDT Wed Jul 28 2021
Areas affected...portions of east-central and northeast
MN...northern WI
Concerning...Severe potential...Tornado Watch likely
Valid 282209Z - 290015Z
Probability of Watch Issuance...95 percent
SUMMARY...Rapid development of supercell thunderstorms is
anticipated in the next few hours, with a risk for very large hail,
damaging winds, and potentially a few tornadoes. A Tornado Watch
will likely be issued prior to 00z.
DISCUSSION...A warm front extended south/southeast across
central/southern MN at 22z, and this front will continue to move
east through this evening as a weak surface low moves east across
central MN. Latest visible imagery reveals moderate/towering cumulus
over central MN north of the Twin Cities area, embedded within a
larger area of clouds over central/northern MN and northern WI.
Current expectations are for thunderstorms to develop in the next
few hours near the warm front and move southeast during the evening.
Northwesterly deep-layer shear of 45-55 kts in the vicinity of the
front will support intense supercells initially, and
locally-enhanced 0-3 km SRH will be favorable for low-level rotation
and potential for tornado development. Steep mid-level lapse rates
will also support a risk for very large hail, and damaging winds are
also expected. Current thinking is that the tornado threat will
warrant a Tornado Watch for the first few hours after initiation
given the near-storm environment, with eventual transition into a
fast-moving MCS with widespread damaging wind potential later this
evening/overnight.
A Tornado Watch will likely be coordinated with affected NWS Weather
Forecast Offices prior to 00z.
..Bunting/Goss.. 07/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DLH...ARX...MPX...
LAT...LON 45009333 45859421 46629429 47149383 47309309 46959223
46869141 46549074 46259042 45789046 45209061 44779106
44629200 45009333SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 7:33 PM CDT | Mesoscale Discussion | SPC | Dakota, Dodge, Fillmore, Freeborn, Goodhue, Houston and 8 more | 87 min |
| Jul 27, 8:03 PM CDT | Severe Thunderstorm Watch | SPC | Dakota, Dodge, Fillmore, Freeborn, Goodhue, Houston and 8 more | 6 hr |
| Jul 27, 10:35 PM CDT | Mesoscale Discussion | SPC | Dodge, Fillmore, Houston, Mower, Olmsted, Winona | 55 min |
| Jul 28, 2:48 AM CDT | Mesoscale Discussion | SPC | Big Stone, Chippewa, Douglas, Grant, Kandiyohi, Lac qui Parle and 12 more | 2 hr |
| Jul 28, 10:28 AM CDT | Mesoscale Discussion | SPC | Aitkin, Beltrami, Cass, Clearwater, Hubbard, Itasca | 2 hr |
| Jul 28, 12:59 PM CDT | Mesoscale Discussion | SPC | Koochiching, Lake, Lake of the Woods, Saint Louis | 2 hr |
| Jul 28, 3:32 PM CDT | Mesoscale Discussion | SPC | Beltrami, Clearwater, Lake of the Woods, Mahnomen, Red Lake | 118 min |
| Jul 28, 12:50 AM CDT | Mesoscale Discussion | SPC | Grant, Iowa, Lafayette, Richland | 55 min |
Nearby
Mesoscale Discussions in Minnesota, 2021Mesoscale Discussions in Wisconsin, 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.