Mesoscale Discussion 433

Issued

Apr 27, 2021, 11:05 AM CDT (16:05 UTC)

Expired

Apr 27, 2021, 1:30 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Menominee County, MI, Clark County, WI, Door County, WI, Eau Claire County, WI, Langlade County, WI, Marathon County, WI, Marinette County, WI, Menominee County, WI, Oconto County, WI, Shawano County, WI

The Green Bay radar (KGRB), 79 km from the middle of the area, began a volume at 16:09 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.

484 
ACUS11 KWNS 271605
SWOMCD
SPC MCD 271605 
MIZ000-WIZ000-271830-

Mesoscale Discussion 0433
NWS Storm Prediction Center Norman OK
1105 AM CDT Tue Apr 27 2021

Areas affected...Portions of northern/central WI and the U.P. of MI

Concerning...Severe potential...Watch unlikely 

Valid 271605Z - 271830Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated large hail may occur with elevated storms over
the next couple of hours. Watch issuance appears unlikely.

DISCUSSION...A few supercells have recently developed over
northeastern WI to the north of a surface front. These storms will
likely remain elevated, and appear to be focused along a temperature
gradient at 850 mb. The 12Z sounding from GRB shows the presence of
steep mid-level lapse rates (8.3 C/km in the 700-500 mb layer),
which is clearly supporting robust updrafts given the ongoing strong
to severe convection. Even though low-level moisture is expected to
remain quite limited north of the front, there is enough mid-level
moisture combined with steep lapse rates aloft to support weak
elevated instability. Large-scale forcing is somewhat nebulous, with
this recent activity probably tied to a low-amplitude shortwave
trough traversing parts of the Upper Midwest per recent water vapor
satellite imagery. There is uncertainty with how much additional
robust convection will develop in this regime, especially to the
west of the ongoing storms into central WI. But, occasional large
hail will likely remain a concern with the strongest storms in the
short term across parts of northeastern WI and the far southern part
of the U.P. of MI. Given expectations for a fairly isolated severe
threat through the early afternoon, watch issuance is unlikely at
this time.

..Gleason/Hart.. 04/27/2021

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

ATTN...WFO...MQT...GRB...ARX...MPX...

LAT...LON   44699136 44959093 45678787 45738712 45648633 45278644
            44968676 44728732 44479129 44699136

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.