Mesoscale Discussion 1957

Issued

Dec 5, 2021, 4:22 AM CST (10:22 UTC)

Expired

Dec 5, 2021, 10:15 AM CST

In force

6 hr

Issued by

the Storm Prediction Center

Concerning

Heavy snow

The Duluth radar (KDLH), 81 km from the middle of the area, began a volume at 10:23 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.

876 
ACUS11 KWNS 051022
SWOMCD
SPC MCD 051022 
MIZ000-WIZ000-MNZ000-051615-

Mesoscale Discussion 1957
NWS Storm Prediction Center Norman OK
0422 AM CST Sun Dec 05 2021

Areas affected...central and northeastern Minnesota into northern
Wisconsin/western Upper Michigan

Concerning...Heavy snow 

Valid 051022Z - 051615Z

SUMMARY...A band of moderate to heavy snowfall will shift gradually
eastward and northward across central and northeastern Minnesota,
northern Wisconsin, and into western Upper Michigan.  Rates
exceeding 1" per hour are expected in heavier bands.

DISCUSSION...A mid-level vort max -- now crossing southern and
eastern North Dakota per water vapor imagery -- is forecast to dig
east-southeastward with time.  As this occurs, a north-northwest to
east-southeast zone of warm advection/isentropic ascent will
persist, as southerly low-level flow near 50 kt shifts eastward
across the upper Mississippi Valley region through midday.  This
ascent will allow a band of moderate to heavy snowfall -- currently
ongoing from north-central North Dakota to east-central Wisconsin --
to continue.  With time, the band is expected to drift slowly
northward, focusing from central/northeastern Minnesota to northern
Wisconsin/western Upper Michigan through late morning.  As this
occurs, some increase in intensity of the band is expected,
corresponding with some enhancement in snowfall rates with time. 
Within the heaviest portions of the band, snowfall rates in the 1"
to 1 1/2" per hour range are expected.  As the upper system
advances, a gradual west-to-east shift of the area of heaviest
snowfall is expected, tapering with time across North Dakota, and
spreading across Lake Michigan toward northern Lower Michigan
through late morning.

..Goss.. 12/05/2021

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

ATTN...WFO...MQT...GRB...DLH...ARX...MPX...FGF...

LAT...LON   47329481 47759350 47889178 47819051 47178983 46218744
            45528718 45068746 44908945 45539075 46569332 46669485
            47329481

Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Minnesota, 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.