Mesoscale Discussion 1362

Issued

Jul 27, 2021, 4:00 AM CDT (09:00 UTC)

Expired

Jul 27, 2021, 6:30 AM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Minneapolis radar (KMPX), 69 km from the middle of the area, began a volume at 09:01 UTC, the scan nearest the moment this went out.

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817 
ACUS11 KWNS 270900
SWOMCD
SPC MCD 270900 
WIZ000-MNZ000-271130-

Mesoscale Discussion 1362
NWS Storm Prediction Center Norman OK
0400 AM CDT Tue Jul 27 2021

Areas affected...Portions of central/eastern MN and far western WI

Concerning...Severe potential...Watch unlikely 

Valid 270900Z - 271130Z

Probability of Watch Issuance...20 percent

SUMMARY...A threat for mainly isolated large hail may exist early
this morning with elevated storms. The coverage and intensity of
these storms remain uncertain, and watch issuance appears unlikely
at this time.

DISCUSSION...A couple of storms have recently developed across parts
of east-central MN in a low-level warm advection regime
characterized by 25-35 kt of west-southwesterly flow in the 0-2-km
layer AGL per recent VWP estimates from KMPX. This convection is
currently located near a surface front/composite outflow boundary
from earlier storms across WI, and is likely slightly elevated. If
these storms can be maintained and move southward over the next
couple of hours, they will encounter a rather unstable airmass with
MUCAPE around 1500-3000 J/kg. The flow above the boundary layer
veers quickly to northwesterly while also strengthening, and about
45-50 kt of effective bulk shear will easily support supercell
structures. Steep mid-level lapse rates noted on the 00Z ABR/MPX
soundings, coupled with the rather favorable thermodynamic and
kinematic environment, suggest an isolated threat for large hail
with any supercell that can be sustained. Occasional strong to
severe wind gusts also appear possible given the moderate to strong
instability south of the boundary. However, considerable uncertainty
remains regarding storm coverage and intensity, as large-scale
forcing for ascent at mid levels remains nebulous. Given these
uncertainties, watch issuance appears unlikely at this time, but
observational trends will be closely monitored.

..Gleason/Edwards.. 07/27/2021

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

ATTN...WFO...DLH...ARX...MPX...

LAT...LON   45209477 46019475 46359388 46269314 45799236 45309152
            44589185 44449361 45209477

Mesoscale Discussions in Minnesota, 2021Mesoscale Discussions in Wisconsin, 2021Every mesoscale discussion in 2021

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.