Mesoscale Discussion 1132

Issued

Jun 30, 2021, 2:13 PM EDT (18:13 UTC)

Expired

Jun 30, 2021, 4:15 PM EDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

5%

Counties Delta County, MI, Dickinson County, MI, Menominee County, MI, Brown County, WI, Door County, WI, Florence County, WI, Forest County, WI, Kewaunee County, WI, Langlade County, WI, Marathon County, WI, Marinette County, WI, Menominee County, WI, Oconto County, WI, Outagamie County, WI, Shawano County, WI, Waupaca County, WI

The Green Bay radar (KGRB), 69 km from the middle of the area, began a volume at 18:14 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.

752 
ACUS11 KWNS 301813
SWOMCD
SPC MCD 301813 
MIZ000-WIZ000-302015-

Mesoscale Discussion 1132
NWS Storm Prediction Center Norman OK
0113 PM CDT Wed Jun 30 2021

Areas affected...Northeast Wisconsin and parts of Michigan's
Upper-Peninsula

Concerning...Severe potential...Watch unlikely 

Valid 301813Z - 302015Z

Probability of Watch Issuance...5 percent

SUMMARY...Thunderstorms may gradually intensify through the
afternoon hours and pose a damaging wind/hail risk. However, this
threat will remain spatially confined to northeast Wisconsin and the
south-central Upper-Peninsula of Michigan. A watch is not expected.

DISCUSSION...Midday water-vapor imagery shows a mid/upper-level
trough moving southward out of southern Canada into the western
Great Lakes region. Lift ahead of this wave is slowly overspreading
northern WI and the U.P. of MI where temperatures are slowly warming
into the upper 70s and low 80s amid dewpoints in the 60s. Warming
surface temperatures and gradual cooling aloft is supporting modest
instability (around 500 J/kg MLCAPE in recent mesoanalysis
estimates), but further warming should lead to a slow increase in
instability through late afternoon. 30-40 knot flow above 6 km
(sampled by the KMQT VWP) associated with the approaching wave is
providing sufficient deep-layer shear for some storm organization. 

Recent surface observations hint at a subtle boundary/surface trough
moving southward across the U.P. and northern WI, which may be the
impetus for the ongoing early convection south of Marquette, MI.
Deep-layer flow oriented along the subtle initiating boundary will
favor further upscale growth for these initial storms, which may
pose a damaging wind threat in the near-term. Additional convection
developing later this afternoon along the boundary and/or along any
lake breezes may initially be discrete and pose a hail threat before
merging into clusters. Overall, this threat is expected to remain
fairly confined to northeast WI and the south-central U.P., so a
watch is not expected.

..Moore/Thompson.. 06/30/2021

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

ATTN...WFO...MQT...GRB...

LAT...LON   44378916 44558960 44798981 45138970 45658907 46078852
            46378725 46168659 45888638 45548651 44968701 44418752
            44218787 44288844 44378916

Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Michigan, 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.