644
FXUS63 KMQT 091115
AFDMQT

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

.KEY MESSAGES...

- Winter Weather Advisories remain in effect 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 today, bringing heavy snowfall rates of
  1-2"/hr. Marquette and Alger counties remain in a Winter
  Storm Warning as accumulations climb to 8+ inches in the axis
  of heaviest snowfall.

- 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 405 AM EST Sun Nov 9 2025

KMQT radar returns show lake effect snow ongoing across the Lake
Superior-adjacent counties of the UP. The strongest returns have
suggested 1"/hr rates, though those rates have not been focused over
any given location for an extended period of time and have been
isolated to scattered so far. A couple of mesovorticies have been
noted on radar over the last few hours, which is expected given not
the strongest flow over Lake Superior and the strong thermodynamics
present as 850mb temperatures have fallen to -13C over a Lake
Superior that`s running a couple C warmer than normal at around 9C.
Any mesovorticies that do make landfall going forward will carry the
threat of 1+"/hr snowfall rates and potentially hazardous travel
conditions.

Aloft, the 500mb pattern consists of an elongated closed low
extending across James Bay from northern Ontario to Quebec,
contrasting with tall longwave ridging over the Rockies. Over the
next couple of days, the closed low will split, with the Quebec
portion slowly retrograding to the north and northwest while the
northern Ontario section rotates through the Great Lakes basin today
and Monday. The latter section will bring significant PVA which will
add even more forcing to the already ongoing lake effect setup.
While a discrete surface low is not expected to form with this lobe
of the closed low, the impact on the surface wind field is still
felt as a convergent wind pattern is expected to set up. Synoptic
ascent, local convergence, and supportive thermodynamics (soundings
showing saturated inversion heights to nearly 14 kft and around 1000
J/kg of lake-induced CAPE) will provide a prime setup for a strong,
dominant lake effect snowband which will have the potential to bring
impactful winter weather today and tonight. The 00Z HREF suite is
almost unanimous in showing a dominant band impacting western Alger
County this morning, then drifting west across Marquette County to
near the Marquette/Baraga line this afternoon and evening before
drifting back across Marquette County towards Alger County overnight
tonight. With this dominant band comes 20-40% chances of 1+"/hr
snowfall rates and 10-20% chances of 2+"/hr rates. Orographic lift
will also help the forcing as this band intersects the steep Lake
Superior-facing terrain of Marquette County. Outside of the dominant
band, scattered lake effect showers are expected in the north wind
lake effect snow bands, bringing 1-6 additional inches of snowfall
for most of the UP, except for the south-central. While some
clarity was provided in the expected solution with this forecast
package, no changes have been made to the headlines with this
package as the impacts match the headlines pretty well already.

The UP becomes positioned in the wake of the mid level shortwave
overnight into Monday, but a weak low level/surface trough drops
south across the area, shifting winds and LES out of the northwest
and once again reinvigorating shower coverage, though with less
local convergence, drier air, and lower inversion heights, a
dominant band is not expected and snow rates/impacts should be less.
Despite this, with 1-3"/6hr rates still expected along Lake
Superior, headlines remain warranted for the Monday period,
especially as the Monday commutes nudge the impact potential higher.
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,
though the HREF does hint at up to 40% chances of exceeding 30 mph
over the Keweenaw and in Marquette County. This wind, while not
extreme, could further complicate travel conditions.

Uncertainty then grows into the middle portions of next work week as
the split upper troughs reconcile into longwave troughing that
gyrates throughout eastern Canada and the eastern CONUS, with
individual embedded shortwaves influencing the precipitation
forecast. Because the lake is so warm and the current airmass is so
cool, the lake-850mb deltaTs remain 40-70% likely to support lake
enhanced to lake effect precipitation throughout the week even with
a warmer airmass moving overhead. However, with the aforementioned
warming, not all of the lake effect precipitation will fall as snow,
as temperatures will warm to above freezing for portions of the
mid to late week. The gradual warming trend continues into next
weekend as the ridging over the central CONUS is expected to
encroach into the region in some fashion. The CPC gives over 50
percent chances that the interior west will see above normal
temperatures in the 8- 14 day period, with the rest of the UP in
the 40-50 percent range.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 614 AM EST Sun Nov 9 2025

Lake effect snow showers will continue to impact all TAF sites in
this period bringing primarily MVFR categories under northwesterly
to northerly flow. Periodic LIFR can`t be ruled out at KCMX this
morning and IFR at KSAW this morning and afternoon given the
potential for stronger snow bands. As the day progresses, activity
will focus into western Upper Michigan, allowing KSAW to improve
categories, potentially to VFR. Snow showers return tonight though,
bringing the terminal back to MVFR/IFR.

&&

.MARINE...
Issued at 405 AM EST Sun Nov 9 2025

Given a strong gradient between high pressure over the Plains and
low pressure passing south of the Great Lakes today, wind gusts out
of the northwest to northeast will be in the 20-25 kt range today.
Tonight, expect winds to become more uniformly out of the north to
north-northwest, with a few gale force gusts to 35 knots possible
(around 20-30%), but primarily in the 25-30 kt range. During this
time, wave heights build to 4-7 ft, locally to 8+ ft just north of
the tip of the Keweenaw Peninsula. As ridging shifts over the UP by
Monday night, winds fall below 20 kt and waves fall below 4 ft.
Tuesday, a low pressure passing north of the lake will build winds
to near gale-force, though uncertainty is high given spread in the
modeled strength and track of this low. The active pattern continues
through the work week as periodic disturbances will occasionally
build wind gusts to 20-30 kt and waves up to 4-7 ft, and potentially
up to 8-10 ft if strong winds can persist in a given direction.

&&

.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...GS
AVIATION...JTP
MARINE...GS