743
FXUS63 KMQT 021957
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
357 PM EDT Tue Sep 2 2025

.KEY MESSAGES...

- A cold front will move through the region tonight and Wednesday.
This will bring widespread light to moderate rain to Upper Michigan
and breezy winds in the Keweenaw.

- A cool airmass will build over the Upper Great Lakes late this
week, providing the region below normal temperatures all the way
to the week`s end.

- A few gale force gusts are expected over Lake Superior Wednesday
into Wednesday night, mainly west and north of the Keweenaw
Peninsula.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 356 PM EDT Tue Sep 2 2025

Warm southerly flow brought temperatures into the 70s this afternoon
over much of the U.P. with mainly sunny skies over much of the
central and east other than a few fair weather cumulus. Over
the west a decaying convective system was spreading cloud cover
into the area along with a few showers. An upper level low
pressure was over north central Manitoba moving towards the
Great Lakes and a cold front extended from northern and western
Ontario into the northern Plains. This system will be ushering
in fall like weather for the remainder of the week.

For tonight...as the remnants of the convective system push through
the western and central U.P showers and a few thunderstorms are
expected to develop this evening. More widespread showers and
thunderstorms will move across the U.P late tonight into the early
morning hours as the cold front moves though the area. The
atmosphere will be lacking instability and shear so not expecting
any strong thunderstorms. Rainfall amount will generally be less
than a half inch.

Temperatures will fall over the western U.P behind the cold front to
around 50 with 60s for lows in the east.

An upper level low pressure will dive south from Ontario to Lake
Superior on Wednesday. It then takes on a negative tilt, deepens and
lifts to the north before weaking and stalling/retrograding over
northern Ontario Thursday. The accompanying cold front will continue
to sweep across the U.P early on Wednesday bringing showers and a
few thunderstorms with it. Temperatures over the central and east
may start out in the low 60s but expect falling temperatures into
the 40s and 50s by afternoon. As cold air aloft overspreads the area
lake effect rain showers will develop in the northwest wind belts.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 356 PM EDT Tue Sep 2 2025

It will feel much like fall into at least the early weekend with
cool, breezy conditions along with lake effect rain showers at
times. A stronger cliper-like low could bring a round of widespread
rain to the U.P Thursday night into Friday as it moves through the
area. Winds will shift westerly on Thursday with most lake effect
shifting into the west wind belts.

Thursday night into Friday a clipper-like low will swiftly move
southeast out of Alberta into the the Upper Midwest and Great Lakes
region. There is still uncertainty with the exact track of the low
but overall impacts should be low with this system.

Expecting lingering lake effect showers to diminish though the day
on Saturday with dry and cool weather for Sunday. Monday will be see
temperatures moderating into the 60s for most of the U.P.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 140 PM EDT Tue Sep 2 2025

VFR conditions are expected this afternoon with conditions
deteriorating this evening and overnight. A cold front will move
through the area from west to east tonight into early Wednesday
bringing a period of showers and thunderstorms. Expect MVFR and
possibly IFR conditions with the showers/storms ahead of the front
this evening into the overnight. Behind the front CIGs will fall to
IFR and LIFR through the remainder of the TAF period.

&&

.MARINE...
Issued at 356 PM EDT Tue Sep 2 2025

Deepening low pressure will dive into Lake Superior tonight. Once it
moves into the lake, it will quickly lift northeast, reaching
Ontario by Wednesday morning. The low will pull a cold front through
the lake during this period, resulting in southwesterly winds
shifting north-northwesterly to northwesterly. Mostly anticipating
20-25 kt winds in this southwesterly flow, but a stronger low level
jet setting up east of the Keweenaw tonight may support winds
upwards of 30kts with isolated gale gusts. Mixing at the lakeshore
is also anticipated to result in localized downsloping accelerations
in areas where terrain is perpendicular to the wind direction. This
could enable these stronger winds near the Lake Superior lakeshores
between Big Bay and Grand Marais. Thunderstorms ahead of the front
will also be possible. Behind the front Wednesday and Wednesday
night, cold air advection and pressure rises will result in north-
northwesterly to northwesterly increasing to near 30kts lakewide.
Guidance continues to present mixed signals for gales; however,
confidence isn`t high enough to warrant a warning at this time.
Significant wave heights build to 5-8ft north and east of the
Keweenaw Wednesday.

Winds become more westerly then southwesterly Thursday. Relaxing
pressure gradient and advection aloft will allow winds to fall to
near 20kts by Thursday night. These winds again increase Friday as a
clipper-like low presses quickly into Minnesota/Wisconsin Thursday
night. This low will reach northern Lake Michigan Friday morning
before entering Quebec Friday evening. Westerly to northwesterly
wind increasing to near 30kts is expected, with similarly to
tonight, low potential (~25% or less) for gales. Expecting winds to
gradually relax Saturday, then fall back below 20kts Sunday night.
These lighter winds hold into at least midweek next week.

&&

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

&&

$$

SHORT TERM...NL
LONG TERM...NL
AVIATION...NL
MARINE...JTP