Alert archive / Minnesota / Mesoscale Discussions in 2021

Mesoscale Discussion 1374

July 28, 20214 counties in Minnesota

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2021, 12:59 PM CDT for 4 counties in Minnesota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 28, 2021, 12:59 PM CDT (17:59 UTC)
Expired: Jul 28, 2021, 3:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch possible
Chance of a watch: 40%

Counties Koochiching County, MN, Lake County, MN, Lake of the Woods County, MN, Saint Louis County, MN

The radar

The Duluth radar (KDLH), 215 km from the middle of the area, began a volume at 17:57 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

International Fa, MN (KINL), launched 12:00Z, 6.0 hours before the alert went out and 27 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 285 J/kg
Mixed-layer CIN: -422 J/kg
Mixed-layer LCL: 1229 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 109 m²/s²
0-3 km storm-relative helicity: 190 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted.

573 
ACUS11 KWNS 281759
SWOMCD
SPC MCD 281759 
MNZ000-282000-

Mesoscale Discussion 1374
NWS Storm Prediction Center Norman OK
1259 PM CDT Wed Jul 28 2021

Areas affected...North-Central/Northeast MN...MN Arrowhead

Concerning...Severe potential...Watch possible 

Valid 281759Z - 282000Z

Probability of Watch Issuance...40 percent

SUMMARY...Large hail is possible this afternoon from north-central
MN through the MN Arrowhead.

DISCUSSION...Recent surface analysis places a cold front from far
southeast Saskatchewan southwestward across far northwest MN and
through southeast ND. A surface low resides along this boundary
about 15 miles east of GFK. A warm front extends arcs southeastward
from this low across north-central MN and then back more southward
across east-central MN. A secondary low exists over far southeast
ND, with another warm front extending southeastward across southwest
MN. This second warm front is demarcated well by the 75 deg F
isodrosotherm. 

Moderate low-level southwesterly flow is in place within the warm
sector of MN, and the attendant warm-air advection across the
northern warm front is contributing to thunderstorm development.
Much of this activity is north of the International Border. However,
some more southerly development has occurred, including one fairly
strong storm moving across Koochiching County. Persistent warm-air
advection could result in additional development across this region.
The overall environment is characterized by steep mid-level lapse
rates and strong flow aloft. Recent mesoanalysis estimates bulk
effective shear over the region exceeds 50 kt. As a result, any
updrafts that can persist should be able to organize/rotate, with an
attendant threat for large hail.

..Mosier/Hart.. 07/28/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DLH...FGF...

LAT...LON   49349520 49199414 48219030 47579086 47229234 48349542
            48869578 49349520

SPC 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, 3:32 PM CDT	Mesoscale Discussion	SPC	Beltrami, Clearwater, Lake of the Woods, Mahnomen, Red Lake	118 min
Jul 28, 5:09 PM CDT	Mesoscale Discussion	SPC	Aitkin, Anoka, Benton, Carlton, Chisago, Crow Wing and 7 more	2 hr

Nearby

Mesoscale Discussions in Minnesota, 2021 Every 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.