Mesoscale Discussion 1593

Issued

Aug 24, 2021, 2:02 PM EDT (18:02 UTC)

Expired

Aug 24, 2021, 3:30 PM EDT

In force

88 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Benzie County, MI, Kent County, MI, Lake County, MI, Manistee County, MI, Mason County, MI, Mecosta County, MI, Montcalm County, MI, Muskegon County, MI, Newaygo County, MI, Oceana County, MI, Osceola County, MI, Ottawa County, MI, Wexford County, MI

The Grand Rapids radar (KGRR), 68 km from the middle of the area, began a volume at 18:03 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.

656 
ACUS11 KWNS 241802
SWOMCD
SPC MCD 241802 
MIZ000-241930-

Mesoscale Discussion 1593
NWS Storm Prediction Center Norman OK
0102 PM CDT Tue Aug 24 2021

Areas affected...western lower Michigan

Concerning...Severe potential...Watch unlikely 

Valid 241802Z - 241930Z

Probability of Watch Issuance...20 percent

SUMMARY...A band of storms along the western shores of Lake Michigan
may pose some risk for damaging wind gusts as they cross the lake
and move onshore into Lower MI. Uncertainty on convective evolution
is very high.

DISCUSSION...As of 1750 UTC, regional radar imagery showed a line of
thunderstorms in the vicinity of Green Bay, WI moving offshore onto
Lake Michigan. Ahead of a weak mid-level disturbance, these storms
have produced occasional strong gusts (41 kt @ KMTW) over eastern WI
in the last couple of hours. SPC mesoanalysis indicates around
2000-3000 J/kg of MUCAPE is present with slightly less buoyancy
available downstream over lower MI. Vertical shear ahead of the weak
mid-level shortwave is not overly robust around 25-30 kt, but should
be adequate for continuation of the ongoing multicell line. 

Uncertainty on storm evolution remains high as storms approach and
cross Lake Michigan. Latest CAM guidance suggests rapid weakening of
ongoing storms may occur given downstream inhibition and weakening
vertical shear over the lake and lower MI. However, recent cumulus
development and SPC mesoanalyis hint at better potential for
downstream destabilization and storm longevity. Given the magnitude
of buoyancy available, a few damaging wind gusts cannot be ruled out
as storms cross the lake and move onshore into MI though uncertainty
remains very high.

..Lyons/Kerr.. 08/24/2021

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

ATTN...WFO...APX...GRR...

LAT...LON   42678551 42568578 42568664 43148674 43878699 44598668
            44738635 44448559 44078524 43638510 43248508 42798517
            42678551

Mesoscale 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.