645
FXUS63 KMQT 090520
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1220 AM EST Sun Nov 9 2025

.KEY MESSAGES...

- Winter Weather Advisories remain in effect beginning tonight
  through Monday for a widespread 2-4 inches of snowfall for all
  except the south-central UP.

- The formation of a strong lake effect band impacting the
  central UP is expected late tonight into Sunday, bringing
  heavy snowfall rates of 1-2"/hr. Upgraded Marquette and Alger
  counties to a Winter Storm Warning.

- Another round of moderate to heavy lake effect snow is
  expected on Monday, but confidence is lower regarding timing
  and placement.

- While snowfall rates fall off significantly late Monday into
  Tuesday, active weather pattern continues through the work
  week with a slight warmup expected to bring periodic rain and
  snow showers to the forecast.

&&

.DISCUSSION...
Issued at 359 PM EST Sat Nov 8 2025

Afternoon RAP analysis and GOES water vapor imagery show the broad
mid level troughing pattern over eastern CONUS/Canada with a ridge
building over the west coast. Embedded in the pattern includes a
closed low over far northern Ontario and two main shortwaves
orbiting along the periphery of the Great Lakes Basin. Mesoscale
analysis indicates 850 mb temps at around -12C over a average Lake
Superior surface temp of 9C, supporting widespread lake effect cloud
cover and lake effect snow showers noted on the radar, mainly over
the east at this time. The drier low level airmass limiting precip
will erode this afternoon and evening, allowing for activity to
increase for tonight. Highs generally are expected in the 30s this
afternoon.

The main focus and challenge of the forecast is tonight through
Monday. The closed low begins to elongate, sending a shortwave
across the area early on tonight and bringing 850 mb temps down to
between -13C to -15C. Low level moisture fills in and inversion
heights rise to ~7kft. This results in an uptick in LES shower
coverage between 1-3Z Sunday over the west and Keweenaw. The wave
makes it to the north-central between 3-6Z while showers in the far
west begins to wean a bit; scattered coverage over the east
maintains during the entire period. Temps tonight settle into the
mid teens to upper 20s, coldest interior west where some single
digit wind chills are expected.

Sunday morning and afternoon, a more vigorous shortwave dives over
the west half, re-invigorating shower coverage there once again.
Meanwhile, low level convergence over central Lake Superior early on
Sunday will support development of a dominant LES band extending
from the northern Lake Superior buoy, east of the Keweenaw
Peninsula, and over the central UP: between Skandia, Munising, and
as far south as the Gladstone. With deep moisture, inversion heights
increasing to between 10-15 kft, and BUFKIT soundings indicating
lake educed instability reaching up to as high as 800-1000 J/kg,
plenty of ingredients will be in place for significant lake effect
snowfall rates of 1-2"/HR underneath this band. The 11/8 12Z HREF
probabilities of at least 1"/HR are between 40-70% on Sunday,
highest over far eastern Marquette County and western Alger County
where the band initially develops and maintains over for a few
hours. These probabilities drop off into Sunday afternoon as lower
level winds shift more easterly, pushing this band westward. A lull
in showers is then expected over the east and parts of the central
UP into Sunday night while scattered showers continue over the west
and Keweenaw. Subtle differences in the wind field and placement of
this low level convergence could slightly shift this band around
Sunday morning affecting snowfall amounts, but confidence was high
enough in the morning period for impacts and for areas of
significant snowfall accumulations up to 10-12" to upgrade Marquette
and Alger Counties to a Winter Storm Warning. Widespread amounts of
1-4" is expected over the north to northwest wind snow belts;
accumulations in the south central mainly hold below 2". Locally
higher amounts to 6-8" in the west are expected under persistent LES
bands; sharp snowfall gradients are expected. Intensity of LES will
greatly vary over short distances, resulting in rapidly changing
visibility and road conditions. Impacts to weekend travel are
expected and likely again during the Monday morning commute as well.
Otherwise, highs are expected in the upper 20s to mid 30s.

The UP becomes positioned in the wake of the mid level shortwave
Sunday night into Monday, but a low level/surface trough drops south
across the area shifting winds and LES out of the northwest and once
again reinvigorating shower coverage. Confidence in exact placement
of heaviest LES drops during this period, but supportive conditions
for additional heavy snowfall rates remains (particularly in the
central UP) and impacts are likely (75% chance) during the Monday
morning commute. It will also be a bit gusty along Lake Superior and
in the Keweenaw on Monday. The current forecast reflects 20-30 mph
in those areas, but there is a 40-70% chance for gusts exceeding 35
mph (highest chances in the Keweenaw). Winter Weather Advisories and
the Winter Storm Warnings continue through Sunday night/Monday,
dropping off from west to east as precip and impacts diminish with
drier air and ridging building in. Temps Sunday night are expected
in the mid teens to mid 20s, warming on Monday into the 30s.

15-40% chances for LES continue over the east Monday night into
Tuesday, although accumulations will be limited to a few hundreths
and be more isolated as cyclonic flow weakens and moisture is more
limited. A shortwave Tuesday and Tuesday night may bring a clipper
low through the area, but some guidance keeps this low track further
north through northern Ontario. Regardless, PoPs remain in the
forecast much of the remaining work week over the northwest flow
continues supportive delta-Ts. A wintry mix of snow and rain lake
effect showers is possible during this period before another high
pressure and mid level ridge move in. This also gradually brings
temps back above normal by next weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1220 AM EST Sun Nov 9 2025

Lake effect snow showers will produce variable VFR/MVFR conditions
at Upper Michigan terminals tonight, with N-NW winds around 10 kt.
Snow showers will ramp up in intensity as dominant lake effect snow
bands set up over the far western and north-central U.P. Sunday
morning, with conditions trending down to IFR/low end MVFR in
heavier snow showers at KIWD and KSAW after 12z Sun. Expect
conditions to improve back towards MVFR/VFR with a relative lull in
shower activity after 21z Sun.

&&

.MARINE...
Issued at 359 PM EST Sat Nov 8 2025

A pair of disturbances transit the region tonight, increasing
northerly winds to 20-25 kts. Winds over the east half on Sunday
shift northeast while the west half holds northerly, between 20-30
kts by the end of the day. Winds across the lake increase to 20-30
kts by early Monday morning; strongest winds are expected over the
central third of the lake where there is a 15-30% chance for gale
force gusts to 35 kts Monday morning. This results in waves
increasing to around 4-8 ft on Monday. Winds quickly fall below 20
kts Monday evening, shifting southwest for Tuesday.

The active pattern continues through next work week, increasing
chances of gales (40-60%) Wednesday into Thursday as a low pressure
system tracks to the north.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 1 PM EST Monday for MIZ001-003-
     004-084.

  Winter Weather Advisory until 7 AM EST /6 AM CST/ Monday for
     MIZ002-009.

  Winter Storm Warning until 7 PM EST Monday for MIZ005-006.

  Winter Weather Advisory until 7 PM EST Monday for MIZ007-013-
     085.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

DISCUSSION...77
AVIATION...CB
MARINE...77