745
FXUS63 KMQT 120624
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
224 AM EDT Sat Sep 12 2026

.KEY MESSAGES...

- A batch of showers and storms moves through the western UP early
this morning, potentially redeveloping in the eastern UP this
afternoon.

- The potential for active weather returns early next week in the
form of widespread rain and gusty winds.

&&

.DISCUSSION...
Issued at 224 AM EDT Sat Sep 12 2026

Early this morning, water vapor reveals midlevel troughing over the
north-central CONUS, extending from a midlevel low over the Canadian
Prairie. At the surface, low pressure is tracking through far
western Ontario, dragging a cold front through the Great Lakes.
Judging by the surface wind shift, this is already reaching western
Lake Superior. A line of showers and storms has developed ahead of
it, within the right-rear quadrant of the ~40-50kt LLJ, and showers
and storms should continue to move through the western UP into the
pre-dawn hours. Most of the western UP should see totals of a tenth
of an inch or less, but will not rule out some higher amounts closer
to 0.20in where thunderstorms can hold together. CAMs continue to
show showers falling apart with eastward extent as they contend with
a drier airmass. However, convection may re-fire over the far
eastern UP as we destabilize ahead of the front, but strong storms
are not expected with lackluster CAPE and shear.

Behind the cold front, modest pressure rises and cold air advection
will make for an otherwise breezy and cooler day. Expect an
otherwise cooler day, as temperatures starting in the upper 50s and
lower 60s climb to highs in the lower to mid 70s for most. Breezy
westerlies will be the rule with gusts 25-35 mph common in the
Keweenaw, and up to 20-25mph elsewhere. Sunday, we can`t rule out
some scattered lake effect rain showers or at least lake effect
cloud cover for the NW wind snowbelt as 850 mb temps fall below 5C
(0-2C per NAM or GFS) while the lake average surface temp sits at
~17C. Some of the CAMs are showing somewhat more widespread lake
effect rain coverage, and even hints for a banded structure pointing
into Munising that may be able to provide upwards of a quarter inch
of rain. That said, with a lot of dry air noted in area soundings,
and soundings only showing decent mixing to around 6-8kft, these
higher-end amounts seem rather ambitious.

Looking into early next week, ensembles continue to hone in on a
deepening trough over the Rockies ejecting a deepening surface low
from the northern Plains northeast through Ontario Monday PM through
Tuesday. Operational deterministic models and their ensemble
counterparts are coming into better agreement regarding the track
and timing of the surface low pressure feature, but there still
remains disagreement between each ensemble and their individual
ensemble members. As the trough lifts north of Lake Superior, strong
isentropic ascent within the warm sector will be the focal point for
shower and thunderstorms development. With considerable northward
moisture transport (PWATS near 1.75-2", the 95-99th percentile of
climatology), widespread moderate to heavy rain is possible. Across
the southern half of the UP, the NBM suggests a 50-75% chance for
QPF >1.0" by Tuesday morning, however, this may be high biased as
individual ensembles and the LREF barely scrapes 15-30%.
Additionally, gusty winds are expected both Monday and Tuesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 107 AM EDT Sat Sep 12 2026

A southwesterly LLJ will bring LLWS concerns to the terminals
overnight, with model soundings depicting winds of around 45 kt at
FL020 exiting KSAW after daybreak Saturday. A cold front entering
western Lake Superior will bring scattered showers and potentially a
few embedded thunderstorms across Upper Michigan through early this
morning, prompting the use of PROB30 groups in the TAFs.
Intermittent MVFR ceilings will be possible in any stronger showers
moving over the terminals. Any lingering showers exit to the east 12-
15z Sat, leaving VFR conditions behind the front with gusty west-
northwest winds to 20-25 at at KIWD and KSAW and as high as 30 kt at
KCMX. Winds diminish below 10 kt after 00z Sun.

&&

.MARINE...
Issued at 224 AM EDT Sat Sep 12 2026

Lake Superior:

Winds remain gusty across the lake the rest of tonight and through
the daytime Saturday. Wind gusts to 20-30kts persist out of the
south so far, though winds shift westerly through the morning and
afternoon as a cold front passes through. Some isolated gales to 35
kts are possible (20-40% chance) in the afternoon in and around the
Keweenaw. NW winds linger through Sunday, gusting 20-25 kts in the
east half. More active marine weather returns early next week in the
Monday-Tuesday timeframe as models continue to bring a strong low
pressure system north of the lake. Ensemble probabilities for
southerly and western gales associated with this system are reaching
60-80%, however, there remains uncertainty regarding the gust
potential of southerly gales given the warm lake temps and low level
stability. Historically, southerly wind regimes in the late summer
and early fall tend to be vastly overdone by models in the Great
Lakes, so adjustments have been made to keep peak gusts around 35-40
kts. Ridging returns midweek next week, with winds falling back
below 20kts in response.

Northern Green Bay and northwestern Lake Michigan: Gusty SW winds 20-
30 kts persist the rest of tonight and into the morning. A cold
front moves through later this morning and into the afternoon,
turning winds more westerly with gusts diminishing between 10-15 kts
by the evening. Winds remain below 20kts through Sunday moring
before beginning to increase out of the south late in the day. Active
marine weather returns early next week with the passage of a
potentially strong low pressure system to the north. This, in turn,
will increase winds to near or above gales in the Monday-Tuesday
timeframe. Ridging returns midweek next week, with winds falling
back below 20kts in response.

&&

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

&&

$$

DISCUSSION...BW/LC
AVIATION...CB
MARINE...BW/LC