Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 052342
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
542 PM CST Sun Dec 5 2021

.DISCUSSION...(This evening through Saturday)
Issued at 434 PM CST Sun Dec 5 2021

Summary: A winter system continues to pivot across the Northland
this evening bringing widespread snowfall. As the low passes across
the region winds will switch to out of the northwest and become very
strong with gusts upwards of 45 mph at times. Blowing snow will be a
concern. Additionally, temperatures will plummet with the departing
low and early morning wind chills across our western counties may
drop to -25F.

Our first large winter storm continues to churn across the region
this evening. The surface low pressure is centered over west central
MN. Radar also depicts a band of heavy snow traversing St. Louis
County and along the the North Shore. Winds continue to remain
strong as the surface low continues to deepen as it slides east.
Snowfall has exponentially ramped up along the North Shore as the
lake effect component combines with a very deep DGZ. Webcams show
difficult travel conditions along HWY 61 and the rest of the
Arrowhead with the roads being completely covered in snow.

We have had a few issues pop up with this particular storm system.
Water vapor reveals a dry slot aloft that is causing freezing
drizzle to fall over portions of the region. This change in
precipitation type has eaten away at some of our snow totals and
with this forecast package we have tried to capture the lower snow
totals. As the night progresses the low will pass across Duluth
heading east. On the backside of this low is an extremely tight
pressure gradient. Very gusty winds will be expected with speeds
upwards of 45 mph possible. This will lead to areas of blowing snow
and snow drifts. With the strong NW winds filtering in on the
backside of the low the chances of a gravity wave forming in the lee
of the North Shore are high. This lingering feature could bring an
additional couple of inches across northern WI and the Bayfield
Peninsula.

With the winds shifting to out of the northwest we will see lake
effect snow showers transition from the North Shore to the South
Shore overnight as well. Iron, and Ashland are under the gun for an
additional 3 to 6 inches after midnight.

Putting snow aside there is concern about the arctic air that
plunges in behind the system. Overnight lows for tonight are
expected to bottom out around -5F along our western edge. However,
the strong northwest winds could lead to wind chills around -25F in
the morning. A wind chill advisory may be needed. These cold
temperatures stick around through Monday with Tuesday morning also
expected to be on the chilly side.

By the midweek point temperatures begin to trend up once again with
highs climbing above freezing on Thursday. Additionally, Thursday
will bring our next chance for precipitation across the Northland
again. At this time it is too soon to narrow down in snow totals.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 542 PM CST Sun Dec 5 2021

The large system that brought the wintry mix of precipitation types,
along with some accumulating snow, will depart the region Monday.
This will bring a gradual end to the precipitation for much of the
area. Gusty northwest winds will affect all terminals tonight
through Monday. Cigs and vsbys will vary based on the intensity of
the snow, and run from LIFR/IFR/MVFR, improving to VFR by Monday
afternoon.

&&

.MARINE...
Issued at 434 PM CST Sun Dec 5 2021

A deepening low pressure is approaching the head of the Lake this
evening with Gales along portions of the North Shore. As the low
crosses there will be a brief lull (and a winds shift) before an
extremely strong pressure gradient develops in the wake of the
system. To account for this we have a Storm Watch out for Monday.
Waves will respond accordingly to the strong winds and will build
in excess of 10 feet today and into Monday downstream of the
prevailing wind direction as the winds shift around the center of
the area of low pressure.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH   5  11  -5  14 /  80   0   0   0
INL  -4   3  -9  10 /  70  10   0   0
BRD   1   5  -3  18 /  50   0   0   0
HYR  10  18  -5  16 /  70  10   0   0
ASX  13  22  -2  16 /  80  40   0   0

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning until 6 AM CST Monday for WIZ001>003-009.

     Winter Weather Advisory until 6 AM CST Monday for WIZ006>008.

     Winter Storm Warning until noon CST Monday for WIZ004.

MN...Winter Storm Warning until 6 AM CST Monday for MNZ010>012-
     018>020-025-026-035-037.

     Winter Weather Advisory until midnight CST tonight for MNZ033-
     034-036-038.

     Blizzard Warning until 6 AM CST Monday for MNZ021.

LS...Storm Watch from 9 PM CST this evening through Monday morning
     for LSZ121-140>148-150.

     Small Craft Advisory until 9 PM CST this evening for LSZ121-
     142>148-150.

     Gale Warning until 7 PM CST this evening for LSZ140-141.

&&

$$

DISCUSSION...Britt
AVIATION...GSF/LE
MARINE...Britt


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