962
FXUS63 KMQT 152351
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
651 PM EST Mon Dec 15 2025

.KEY MESSAGES...

- Expect temperatures to continue warming, with highs above
  freezing on Tuesday.

- Windy conditions are expected late Tuesday into Tuesday night,
  especially in the Keweenaw where there is a 50-75% chance for
  wind gusts exceeding 45 mph.

- Multiple gale events could be seen across Lake Superior this
  week, with the next one expected Tuesday into Wednesday
  morning. A Storm Force Wind and Heavy Freezing Spray event
  could be seen on Thursday.

- A strong Clipper low could bring high winds and a flash freeze
  setup across the area Thursday into Thursday night. Continue
  to monitor the forecast as impacts could change depending on
  the strength and track of the low.

&&

.DISCUSSION...
Issued at 404 PM EST Mon Dec 15 2025

The forecast remains active including a multitude of mid level
waves, increasing in strength and vigor, as they traverse the Upper
Great Lakes this week. The pattern change to a more zonal flow
across the CONUS, which allows better periods of warm air advection
to support precip, but also results in widespread above freezing
temps returning for the first time in weeks on Tuesday/Thursday.
Beyond this coming weekend, temps hover around normal and ensemble
guidance leaves potential for several weak disturbances around the
holiday timeframe, but with lesser impacts and much lower confidence
in timing/track. Starting this afternoon, GOES water vapor imagery
shows a broad mid level ridge over the west CONUS. Closer to home, a
shortwave is observed descending over the eastern UP/Lake Superior.
At the surface, ~1014 mb ridging is extending over the Upper Great
Lakes from a ~1030 mb high over the southeastern U.S. This ridge
overhead gives way to the east and southerly winds increase
overnight into Tuesday. Lingering light LES showers diminish this
evening. Additional accumulations will be minimal with a few tenths
at best given limited moisture and inversion heights already below 5
kft. Temps mainly hold in the teens, hitting their lows shortly
after midnight tonight.

On Tuesday, a clipper system tracks across far northern Ontario.
Strong WAA brings back widespread highs in the 30s with some low 40s
in downslope flow areas. That said, the central UP will be slow to
warm given the strong low level inversion in place. Southwest winds
increase as the pressure gradient tightens, becoming breezy near
Lake Superior and in the Keweenaw. Gusts in those areas will frequent
the 25-35 mph range during the day Tuesday. Elevated instability
noted well by steep mid level lapse rates ahead of a warm front may
provide enough support for convective showers from west to east
Tuesday morning and early afternoon (15-25% chance). P-type looks to
be freezing rain/sleet, although near the lakeshores and far east a
more messy rain/snow/sleet mix could be realized. The limiting
factor will be available moisture as there is a dry layer noted on
model soundings in the low levels. Thus, even if any convection is
able to erode this dry layer and reach the surface, accumulations
will be isolated and struggle to reach 0.01" of QPF. Impacts would
be localized and limited.

Better, although still low, PoPs (20-40%) arrive overnight into
Wednesday morning when the shortwave and cold front track through.
This cooler period introduces light lake effect rain and snow
showers over the northwest wind snow belts. All measurable
accumulations at this point look marginal, if at all. Also, the
colder airmass and pressure rises in the wake of the front yield
another gusty period overnight into Wednesday with widespread
northwest gusts to 20-30 mph. There is a 30-60% chance for 40 mph
gusts near Lake Superior and a 50-75% chance for 45+ mph gusts in
the Keweenaw. Wind Advisories may be considered with the next
forecast package as isolated power outages are possible. Expect any
precip to end by Wednesday afternoon as ridging returns. Temps
settle to the mid teens to mid 20s by Wednesday morning, warming
into the upper 20s to mid 30s during the day.

This dry period will not last long as the most prominent feature of
the forecast arrives. A mid level trough over the Northern Rockies
on Wednesday tracks along the southern end of the Great Lakes Basin
late in the day Thursday into Friday, sending a strong low pressure
system over the Upper Great Lakes. While the spread in guidance on
strength and track is decreasing, there still remains substantial
discrepancies impacting the overall impacts (winds and snow). The
main story is that WAA initially warms temps above freezing into the
30s late Wednesday night into Thursday. This also kicks off a wintry
mix of rain/freezing rain/snow into Thursday, although dry low
levels should hold most precip off until Thursday morning when only
rain and snow is expected. South winds increase into Thursday, with
downslope areas near Lake Superior seeing gusts once again in the 25-
35 mph range. As the low tracks through on Thursday, a cold airmass
quickly moves in from the west transitioning precip over to snow
from west to east and eventually shifting the pattern over to LES
for Friday. This is a good set up for a flash freeze as models
indicate 15-20F changes in 6 hours or less with lows in the single
digits above to low teens by Friday morning, coldest interior west.
Any rain prior to the cold front could create hazardous roads and
sidewalks should this pan out. The strong pressure gradient/pressure
rises on the back side with CAA support strong northwest winds,
potentially as high as 50 mph across the Keweenaw and along the
eastern Lake Superior shoreline (20-40%). These strong winds, in
conjunction with any ice and snow accumulation that occurs during
the event could result in some power outages and minor lakeshore
flooding and beach erosion to the Lake Superior shoreline late
Thursday into Friday morning.

Depending on how far north/south the low ends up tracking will
impact p-types and accumulation amounts. A more north track would
likely see more rain with a delayed onset of snow, leading to less
snow accumulation (supported solution in the EPS members). The
opposite is true if the low takes a further south track (GEFS/GEPS).
This uncertainty is captured well by the NBM percentiles. The 75th
percentile has 4-8 inches over the northwest wind snowbelts while
the 25th struggles to reach 1 inch. What does seem more certain is
the winds with this system. The winds will moreso depend on the
strength of the low, which the canadian and NAM have been notably
weaker than the GFS/ECMWF by around 5-10 mb. Regardless, there is
increasing confidence in impacts, and impacted parties should
continue to monitor the forecast.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 651 PM EST Mon Dec 15 2025

IR satellite imagery shows clouds beginning to scatter out across
the western U.P. including KIWD as of 00z in the wake of a departing
disturbance. Low clouds have been more stubborn to erode farther
east as IFR/low end MVFR cigs prevail at KCMX and KSAW. Increasing
southwest winds will eventually clear out the rest of the U.P to VFR
06-12z as a strong LLJ with winds of 50+ kt at FL020 introduces low
level wind shear to the terminals through the remainder of the TAF
period. An isolated freezing rain shower or two is possible on
Tuesday morning but probabilities are too low to include in the TAF.

&&

.MARINE...
Issued at 404 PM EST Mon Dec 15 2025

Northwest winds fall below 20 kts this evening as a weak ridge moves
through. A stronger clipper system moves across far northern Ontario
on Tuesday, once again increasing southwest winds Tuesday morning to
20-30 kts lakewide. Winds strengthen to gales of 35-45 kts by the
afternoon, strongest winds between Isle Royale and the Keweenaw.
Winds veer northwest Tuesday night as the cold front progresses
through, with strongest winds to 35-45 kts now over the east. Winds
weaken once again to 20 kts or less by Wednesday afternoon as
another ridge quickly passes through the area. Upgraded the Gale
Watch to a Gale Warning, but maintained the same timeframe.

The main concern of the forecast occurs Wednesday night continuing
through Thursday night. A strong low pressure system is progged to
track across the Upper Great Lakes on Thursday. South winds increase
lakewide to 20-30 kts as the pressure gradient strengthens, but
gales to 35-40 kts are possible over the east half into Thursday
morning (30-60% chance). As the system tracks through, a strong
surge of cold air moves in from the west and winds quickly turn
north by Thursday night; chances for 40+ kt gales increase lakewide
to 50-75%. Depending on where the storm tracks will impact the
strength of the winds and timing of wind shifts, but latest
probabilities of storm force winds are around 30% over the central
and eastern waters Thursday afternoon and night. Widespread moderate
to heavy freezing spray is anticipated with this system alongside
significant wave heights of 10-15 ft over the west and 12-22 ft over
the east.

A high pressure moves across the Upper Great Lakes on Friday,
briefly returning winds to around 15-25 kts, but this quickly is
replaced with another low pressure from the west over the weekend
with more 20-30 kt winds and gale potential (33% chance of at least
35 kts over the east). That said, there is plenty of timing and
track uncertainty at this point in the forecast.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning from 7 AM EST /6 AM CST/ Tuesday to 1 AM EST
     /midnight CST/ Wednesday for LSZ162.

  Gale Warning from 4 PM EST /3 PM CST/ Tuesday to 4 AM EST /3
     AM CST/ Wednesday for LSZ241-242.

  Gale Warning from 1 PM Tuesday to 7 AM EST Wednesday for
     LSZ243-244.

  Gale Warning from 4 PM Tuesday to 7 AM EST Wednesday for
     LSZ245>248-265.

  Gale Warning from 1 AM to 7 AM EST Wednesday for LSZ249.

  Gale Warning from 10 AM Tuesday to 7 AM EST Wednesday for
     LSZ250-251-266-267.

  Gale Warning from 7 AM Tuesday to 4 AM EST Wednesday for
     LSZ263.

  Gale Warning from 7 AM Tuesday to 7 AM EST Wednesday for
     LSZ264.

Lake Michigan...
None.

&&

$$

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