Mesoscale Discussion 938

Issued

Jun 12, 2021, 6:19 PM EDT (22:19 UTC)

Expired

Jun 12, 2021, 8:15 PM EDT

In force

116 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

5%

The Grand Rapids radar (KGRR), 52 km from the middle of the area, began a volume at 22:22 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.

018 
ACUS11 KWNS 122220
SWOMCD
SPC MCD 122219 
MIZ000-OHZ000-INZ000-130015-

Mesoscale Discussion 0938
NWS Storm Prediction Center Norman OK
0519 PM CDT Sat Jun 12 2021

Areas affected...Michigan...northern Indiana...and far northwest
Ohio

Concerning...Severe potential...Watch unlikely 

Valid 122219Z - 130015Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated strong, to perhaps severe, thunderstorms will
continue to be possible through the evening hours. Storms will
primarily pose a hail and damaging wind threat. A watch is not
expected.

DISCUSSION...Regional radar imagery shows additional convection
developing along outflow and lake breeze boundaries across northern
Indiana and northern Michigan. Despite a weak frontal intrusion,
strong daytime heating has yielded temperatures in the upper 80s and
low 90s amid dewpoints in the mid-upper 60s. As a result, MLCAPE
values between 1000-2000 J/kg are in place across the region, which
will continue to support new thunderstorm development through at
least sunset and the onset of diurnal boundary-layer cooling. While
the thermodynamic environment is supportive of strong to severe
storms, deep-layer shear is rather modest with only 30-40 knot flow
noted above 6 km in regional VWPs. RAP mesoanalysis and forecast
soundings support this idea with estimates of 25-35 knots of
effective bulk shear. This will limit the potential for a more
robust severe threat, but may support one or two severe storms that
will pose primarily a wind/hail risk (as evidenced by an ongoing
organized supercell in central MI). Given the limited nature of this
threat, a watch is not expected.

..Moore/Dial.. 06/12/2021

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

ATTN...WFO...DTX...APX...IWX...GRR...IND...

LAT...LON   44448540 44658476 44478401 43578397 43028372 42328378
            41808397 41068457 40698509 40528571 40528618 40738668
            41048691 41448674 41728616 42118583 42848561 43708573
            44238558 44448540

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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.