Lake Vermilion Area Weather– December 15-17

KEY MESSAGES

– Dense fog lingering from Cloquet up the higher terrain of the
North Shore through early tomorrow morning.

– A clipper system will bring a brief wintry mix this evening in
far northern Minnesota and then snow to the Northland tonight
through Monday. Light accumulations of up to 2″ for far
northern Minnesota.

– Colder temperatures Tuesday and beyond with occasional snow
chances, including a more potent clipper system on Thursday
with accumulating snow likely.

DISCUSSION

Issued at 331 PM CST Sun Dec 15 2024

Rest of Today through Monday:

The freezing drizzle/precipitation that was hanging around the
North Shore through much of today will comes to an end briefly
late this afternoon into early evening as drier air aloft moves
in. Temperatures have also warmed to at or just above freezing
this afternoon for the North Shore and much of the Northland.
Widespread fog has been persistent today and will continue into
the overnight hours, and linger along the North Shore into
Monday morning. The higher terrain of the Twin Ports into the
North Shore is seeing particularly dense fog due to onshore flow
off of Lake Superior and up the terrain, where a Dense Fog
Advisory remains in effect into Monday morning. Will need to
continue monitoring other portions of central into northeastern
MN for dense fog potential this evening into tonight, but HREF
probabilities are generally 50% or less for those areas at the
moment.

Attention then turns to an approaching low pressure system
currently over central North Dakota that will track into the
Lake of the Woods by 6 AM Monday and then into northwestern
Ontario daytime Monday. Precipitation with this system starts as
more of a wintry mix in north-central MN late this
afternoon/evening, before transitioning over to snow
tonight/Monday morning and continuing as snow through Monday as
precipitation spreads across the Northland. Little to no ice
accumulations are expected during the wintry mix period. Snow
amounts will be light with this system, with totals ranging from
0.5-2″ north of the Iron Range, highest near the International
Border. Accumulations around 0.5″ inches are expected for the
Iron Range to the U.S. Hwy 2 corridor, with lesser accumulations
for areas south of Hwy 2.

One more day of mild temperatures are expected for Monday with
highs in the upper 20s to around freezing on the MN side of the
Northland and low to mid 30s in northwest WI. Winds will become
increasingly gusty out of the west to northwest Monday afternoon
and Monday night behind a cold front, with gusts of 20 to 30 mph
expected. Some locations along the North Shore could see winds
gust to 40 mph Monday night given winds accelerating down the
terrain of the North Shore.

Tuesday-Wednesday:

Colder, below-average air advects into the Northland for Tuesday
and Wednesday behind the cold front. A weak shortwave trough
passing over central/southern Minnesota on Tuesday into Tuesday
afternoon and evening could bring some very light snow (quick
dusting to a couple tenths of an inch) to east-central MN and
northwest WI, though some light lake-effect snow in northern
Iron County should persist into Wednesday. Low temperatures
Tuesday night/Wednesday morning should fall into the single
digits in northeast MN and low to mid teens in northwest WI.
Wind chills are forecast to be in the single digits below zero
in northeast MN and single digits above zero in northwest WI.

Wednesday Night-Thursday Night Clipper System:

Yet another clipper system will quickly cut eastwards across the
northern Plains by late Wednesday night and into somewhere in
the central MN/northern Iowa/western WI vicinity by 12 PM
Thursday and then into the central Great Lakes by early Friday as
highlighted in the latest global ensemble suite of models.
This progression is several hours faster than the previous few
model runs, but there is still some spread in the exact track of
the low pressure system. However, forecast model soundings
suggest that the presence of colder air could lead to deeper
saturation in the dendritic growth zone with this system, which
would result in higher snow to liquid ratios and fluffier snow
with this system. Synoptic forcing with this system also looks a
bit more robust that the other clippers we have seen recently,
so there is a real possibility that this system could produce
shovelable snowfall if this system doesn`t track too far south
of the Northland. NBM 24-hr snowfall probabilities for >2″ on
Wednesday night to Thursday night are currently 30-50% for most
of the Northland, and locally higher to 60-70% along the North
Shore where southeast winds off of Lake Superior should lead to
lake and terrain enhancement to snowfall totals. >4″
probabilities are lower at 15-30% for most of the Northland,
with some locally higher probabilities of 30-45% along the North
Shore and portions of the South Shore.

Temperature-wise, Wednesday night and Thursday night lows are
forecast to primarily be in the single digits above and below
zero with wind chills around zero into the low teens below zero.

Friday-Next Weekend:

Seasonably cold weather in northwest flow should keep below-
average temperatures going for Friday into next weekend, with
morning lows in the -10F to 5F range and morning wind chills
potentially as cold as -5F to -20F depending on how strong winds
will be next weekend.

AVIATION

Issued at 543 PM CST Sun Dec 15 2024

LIFR to IFR conditions persist across the Northland this
evening, with cigs at 200 to 400ft. Expect drizzle and/or
freezing drizzle as temperatures fall, bringing vis down to
less than 1 mile at times. Light snow will move into the area
tonight, impacting terminals through Monday. Best coverage will
be near the international border, with amounts up to 2 inches.
Vis should improve with the snow, but cigs will remain in the
LIFR range. Southeasterly winds to start the forecast period
will veer to the south tonight and then southwest Monday as cold
front moves through the area. Gusts of 18kts are possible
overnight, and increase to 20-25kts Monday afternoon.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR

Issued at 331 PM CST Sun Dec 15 2024

Light southeast winds persist through tonight. Some patchy fog
is possible along the North Shore, as well, but is not expected
to be dense. For Monday, ahead of a clipper system, winds are
expected to switch to southwesterly and then westerly to
northwesterly late Monday into early Tuesday. Wind gusts up to
25 to 30 kt are expected to develop, and some gales to 35 kt are
possible in the Outer Apostle Islands and roughly from Port
Wing to Bayfield along the peninsula Monday afternoon into
Monday night. Additionally, winds are forecast to pick up to
gales of 35 knots along the North Shore Monday evening into
early Tuesday morning due to accelerating winds down the slopes
of the North Shore terrain. Gale Warnings are in effect Monday
evening into early Tuesday where wind gusts to 35 knots are
forecast. Wave heights around 4 to 8 feet are also expected in
this time period along with light/rain snow changing to snow
Monday night. After the clipper system passes through on
Tuesday, winds and waves are expected to decrease out of the
northwest on Tuesday afternoon.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.