416
FXUS63 KMQT 061717
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1217 PM EST Sat Dec 6 2025

.KEY MESSAGES...

- General weather pattern of Clippers followed by lake effect
  snow continues for the next week, perhaps beyond.

- Gusty NW winds this morning will help reduce visibility within
  snow showers and will cause some blowing and drifting snow. A
  few brief gale force gusts are possible (~50%) over the east
  half of Lake Superior this morning.

- Cooler than normal temperatures, with highs in the teens to
  20s and lows as low as the negative single digits
  (particularly Monday AM).

&&

.DISCUSSION...
Issued at 443 AM EST Sat Dec 6 2025

Early morning KMQT radar returns show a number of NW/SE-oriented
bands of snowfall. Some of the bands have penetrated impressively
far inland over the interior central UP, though CAMs show that bands
will retreat to the more typical NW wind LES belts. Lake Superior
remains around 5 C despite the constant cool air over the lake, and
850mb temperatures will remain 50-90% likely to be in the negative
double digits of degrees C throughout the entire forecast period, so
thermodynamic support for LES will be present throughout, regardless
of wind direction. Aloft, expansive and stubborn ridging off the CA
coast contrasts expansive and stubborn troughing over Hudson Bay,
with the resulting flow in between those features being northwest
flow over much of the CONUS. With neither longwave feature in a
hurry to move or deform any time soon, forcing for the sensible
weather over the UP well into mid December will come from two
sources: ridge-riding shortwaves that pass through the Canadian
Rockies and spawn Alberta Clippers, and embedded shortwaves within
the Hudson Bay trough that send periodic cold fronts/surface troughs
over the UP. Except for the strongest of these features, the
synoptic forcing will be generally too weak to provide impactful
winter weather for the UP. However, the cold air and cyclonic
surface flow in the wake of each disturbance will bring enhanced LES
setups periodically which depending on the available moisture,
inversion heights, and DGZ depth, may be worth consideration for
winter impacts.

Today, LES potential will be limited by a drying near-surface layer,
shallow inversion heights (5 kft or less), and limited DGZ
depth/moisture. HREF chances of 1"/6hr is only around 30% in the
strongest bands over the east, so no Winter Weather Advisory will be
necessary. Still, with winds up to 35 mph mixing down to the surface
(per KP59 and KCMX ASOS obs), some reduced visibility has been
observed even in the "weaker" bands and some blowing/drifting snow
may be observed, so some extra care may be needed for the morning
commute. As the pressure gradient relaxes today, expect winds to
relax in kind and become more westerly.

Tonight into Sunday, a confluence of one of each of the
aforementioned types of shortwaves is forecast to occur over the
Midwest, sending a weak surface low well south of the UP. CAMs
bring 15-30% chances of some system snow for the southern half
of Menominee County, but even the 95th percentile of the HREF
only shows an inch of snowfall for that area. Of perhaps more
impact will be the cool northwesterly flow behind the shortwave
supporting further LES. The HREF shows chances of 48-hour snow
totals exceeding 6 inches to be around 30-50% for the Munising,
Grand Marais, and Tahquamenon Falls areas, though as the snow
will be falling at a slow pace over an extended time period, no
headline is anticipated to be issued.

To kick off the work week, high pressure moving south of the region
will help decrease the coverage and intensity of LES with one
notable exception: a weak shortwave will help cause some localized
convergence which could bring some relatively rare SW-wind LES off
of Lake Michigan to Schoolcraft County east of Manistique and Luce
County south of M-28. This feature may bear some monitoring for
brief travel disturbances along the US-2 and M-28 corridors, though
uncertainty still exists in regards to the details of such a
mesoscale feature beyond 48 hours out.

Attention then turns to a pair of clipper lows: a weak one around
1006mb approaching the western UP overnight Monday into Tuesday and
then a much stronger one below 990mb Tuesday night into Wednesday.
Chances of a widespread 1+" of snow are high with the first feature
(~70%), though the ceiling of impacts is low as the chances of over
2" is only 20-40%. The second feature has similar probabilities to
deliver a safe floor of an inch of snowfall, but the ceiling is
higher, with around 20% chances of 4+" of snow by midday Wednesday
along the MI/WI state line.

Ensemble spread then grows in the details of the pattern evolution,
but little broad-scale changes in the weather pattern are expected
until at least mid-December, perhaps longer. Long-duration cool
continental NW flow aloft will help keep temperatures cooler than
normal, with NBM highs generally in the teens to 20s and lows in the
teens near the shores to single digits above and occasionally below
0. The coolest temperatures will come in the interior west where
breaks in the clouds can allow for efficient radiational cooling to
occur. One such example will be Monday morning, where clearing skies
in the interior west allow for NBM lows to fall to around -6 for
Iron County. Mercifully, the coolest temperatures also line up with
high pressure and thus the weakest winds, so wind chill concerns are
low.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1217 PM EST Sat Dec 6 2025

Lake effect snow episode continues in this period, resulting in
flight categories at all sites. Generally light showers are
expected, although an increase in intensity may occur tonight.
Overall, lowest flight categories are expected at KCMX, which is
likely to experience MVFR ceilings and IFR visibilities at times.
KIWD may dip into IFR tonight while KSAW is expected to improve to
VFR later this afternoon/evening. Gusty winds near 20-25kts at KCMX
are also expected today.

&&

.MARINE...
Issued at 443 AM EST Sat Dec 6 2025

A few brief NWerly gale force gusts are possible (~50%) in the east
half of the lake this morning, but a relaxing pressure gradient with
approaching high pressure will allow for gusts to fall to 20 kt or
below by this afternoon. A disturbance aloft will help focus NW
winds tonight into Sunday morning, with NW gusts to 25-30 kt for
Sunday before high pressure once again relaxes the gusts below 20 kt
for Sunday night. A pair of Clipper Lows passing through the Great
Lakes in the first half of next week will bring gusts up to 30 kt,
first out of the southwest Monday PM, then out of the northeast to
north Wednesday AM. Chances of prolonged gales with these Clippers
is currently around 20%, though the chances of more isolated, brief
gale force gusts is higher (~40%). Not much change in the weather
pattern is expected well into the middle of the month, with
occasional Clippers bringing chances for low-end gales, and the
combination of long-duration NWerly winds and cool air mass will
cause occasional moderate freezing spray.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

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