Mesoscale Discussion 861

Issued

Jun 6, 2021, 5:57 PM CDT (22:57 UTC)

Expired

Jun 6, 2021, 7:30 PM CDT

In force

93 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Minneapolis radar (KMPX), 137 km from the middle of the area, began a volume at 22:56 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.

098 
ACUS11 KWNS 062258
SWOMCD
SPC MCD 062257 
MNZ000-WIZ000-070030-

Mesoscale Discussion 0861
NWS Storm Prediction Center Norman OK
0557 PM CDT Sun Jun 06 2021

Areas affected...Portions of the upper mississippi valley

Concerning...Severe potential...Watch unlikely 

Valid 062257Z - 070030Z

Probability of Watch Issuance...20 percent

SUMMARY...A conditional threat for isolated severe thunderstorms
exists this evening across portions of Minnesota and far
northwestern Wisconsin. If storms develop and can persist, then
isolated damaging winds and large hail will be possible. A Weather
Watch appears unlikely due to limited overall storm coverage.

DISCUSSION...Latest surface analysis at 2230Z shows an
eastward-advancing cold front draped from near/south of
International Falls Minnesota southward to Huron South Dakota and
into portions of Nebraska. Strong diurnal heating has occurred
along/east of the cold front, with temperatures generally in the
upper 80s to low 90s (cooler to the north). While low-level moisture
is somewhat modest, 50-60F surface dewpoints are contributing to
MLCAPE values near 500-1500 J/kg. 

While some cumulus congestus clouds and a few radar echoes have
developed over the past hour or so per radar and satellite imagery,
uncertainty remains regarding convective coverage/maintenance due to
the stronger frontal forcing and large-scale ascent remaining to the
north over Canada and only a narrow corridor with little-to-no
convective inhibition. If storms can develop and sustain themselves,
then some transient storm organization would be possible due to
effective bulk shear around 25-30 knots (along/near the front).
Isolated to widely scattered damaging winds would be the primary
threat in the strongest storms due to deep, well-mixed sub cloud
layers. Though, some threat of large hail would also exist with the
strongest updrafts. 

A Weather Watch appears unlikely due to the isolated nature of the
any threat that could develop. Though, trends will continue to be
monitored.

..Elliott/Thompson.. 06/06/2021

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

ATTN...WFO...DLH...MPX...FGF...FSD...

LAT...LON   45829545 48599263 48359056 47379110 45659324 44209543
            44189578 44459613 45829545

Mesoscale Discussions in Minnesota, 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.