750
FXUS63 KMQT 031147
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
747 AM EDT Thu Sep 3 2026

.KEY MESSAGES...

- Rain chances (up to 50%) return to the western UP Thursday evening
into Friday morning, along with low thunderstorm chances (20%) along
the WI border.

- Above-average temperatures will persist through Labor Day Weekend,
with high temperatures in the mid to upper 70s.

&&

.DISCUSSION...
Issued at 357 AM EDT Thu Sep 3 2026

This early morning, 06Z RAP analysis shows a wedge of 1012 mb
surface high pressure extending across the UP, while in Canada GOES
water vapor imagery shows that tonight`s Quebec low resides just
east of James Bay. Local observations show that temperatures have
decreased into the 50s (60s if in proximity to a Great Lake), and a
look out the window indicates a clear sky with visible stars and a
waning gibbous moon.

These clear-sky conditions are expected to change throughout the day
today as a pair of shortwaves ride through the region tonight into
tomorrow morning. Embedded within WNW`ly gradient flow and grazing
the WI border Thursday afternoon, measurable precipitation from this
first wave is anticipated in the southern reaches of the UP near
Marinette, which may receive up to 0.10" and a thunderstorm or two.
The second shortwave arrives in the overnight hours of early Friday
morning, traversing the western UP within NW`ly flow. While most of
the action from this impulse will manifest south of the UP, CAMs at
24 hours out indicate considerable spread in the exact placement of
thunderstorm development. While PoPs range from 20-50% across the UP
with up to 0.20" (best and highest chances south and west), a strong
thunderstorm can`t be ruled out along the WI border or down in
Menominee County. Notable with this system is strongly veering wind
profile with elevated CAPE; low-end easterly surface winds give way
to ~40 kts of WNW`ly flow at 6 km, and some soundings indicate
elevated CAPE upwards of 500 J/kg for locations along the WI border.

As the Quebec low progresses eastward, it will be replaced by
significant upper-level ridging over the central CONUS, resulting in
northwest flow across the Great Lakes for the weekend. High
temperatures are expected to remain above-normal in the mid to upper
70s at least through Sunday due to the influence of this ridging
pattern. Early next week brings the next best chance for
precipitation, with current model guidance indicating a 40-60%
chance of at least 0.25 inches of rain by 8am Wednesday, however,
uncertainty is still high at this time for the timing and extent of
precipitation. Breezy conditions are anticipated as this system
moves through. NBM probabilities of wind gusts at or above 40mph are
between 30-60% in the Keweenaw, highest on Wednesday in the wake of
the cold front.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 747 AM EDT Thu Sep 3 2026

VFR conditions are anticipated at all TAF sites until precipitation
from this evening`s approaching shortwave lowers ceilings and
visibilities. Given light winds and overnight timing, fog formation
in the wake of precip is indicated for IWD & SAW, but was left out
of TAF for now due to low LAMP probs and uncertainty in spread of
precipitation. For IWD, LAMP probabilities for MVFR ceilings are
holding steady at 50% for last few model runs, so MVFR included at
end of period for this site. At CMX, easterlies set in and increase
throughout the day, remaining slightly elevated overnight. Given
track of precipitation, confidence is higher for MVFR ceilings at
SAW, which was confirmed by LAMP probabilities trending upward at
the end of the TAF period.

&&

.MARINE...
Issued at 239 PM EDT Wed Sep 2 2026

Lake Superior: Winds generally remain under 15 kts through Thursday
as a low departs to the northeast. High pressure builds over Ontario
and troughing deepens over the Northern Plains, resulting in a
tighter pressure gradient over the west half of the lake. This
yields periods of east to northeast winds of 15-25 kts late Thursday
through Friday over the western waters. Stronger high pressure
overhead keeps winds light (20 kts or less) lakewide through the
weekend, then 20-30 kt winds return next week with a more prominent
system lifting to the northeast of Lake Superior. Wave heights are
largely expected to remain at 3ft or less through the weekend,
increasing to 2-6ft as winds increase early next week.

Northern Green Bay and northwestern Lake Michigan: Winds generally
remain 15 kts or lower through this weekend as high pressure slowly
builds overhead. A more prominent system lifting northeast over
Manitoba and northwest Ontario early next week increases winds to
around 15 kts with gusts up to 20-25 kts. Wave heights are expected
to remain below 1ft through the weekend, increasing to 2-4ft with
increasing winds early next week.

&&

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

&&

$$

DISCUSSION...RE/LH
AVIATION...RE
MARINE...LH/77