822
FXUS63 KMQT 300810
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
410 AM EDT Tue Sep 30 2025

.KEY MESSAGES...

- A mostly dry and low impact weather pattern with near to above
average temperatures holds this week.

&&

.DISCUSSION...
Issued at 409 AM EDT Tue Sep 30 2025

Early this morning an upper level ridge of high pressure extended
from the lower Mississippi Valley north into the Upper Great Lakes
and then northwestwards into northern Manitoba and Saskatchewan. A
shortwave was over Oklahoma with moisture streaming north along the
west side of the ridge up into WI and the U.P. With ample dry air in
the low to mid levels the main effect of the moisture was high level
bands of clouds traversing the area. Temperatures had stayed warmer
overnight compared to the last few nights, with mainly 50s and 40s
in the usual cold spots. Fog had developed along the Green Bay and
Lake Michigan shorelines and close to the MI/WI border. Overall
visibility was not low enough to warrant any mention of dense fog
but there certainly could be a few isolated/localized areas with
dense fog this morning.

High pressure building into Ontario and Quebec will continue to
bring easterly flow into the U.P today. This, and increased
cloudiness, should help hold temperatures down today compared to
previous days (60s to mid 70s), still above average by several
degrees. Elevated instability will skirt the western U.P but dry sub-
cloud layer air should limit any precipitation from reaching the
ground with any elevated showers that form.

On Wednesday winds begin to turn southeast with temperatures
remaining similar to Tuesday with somewhat cooler air coming in from
the east. Cloudiness will also help limit heating some with
shortwave energy continuing to skirt the area as it lifts north
along the back side of the ridge.

The amplitude of the ridge will begin to lessen late in the week
through the weekend with a strengthening upper level jet from the
southwestern U.S through the Northern Plains into Ontario.
Temperatures will be on the rise for the late week into the weekend
with many areas over the central and western U.P breaking 80F on
Friday. The NBM cools things back into the 70s over the weekend with
low probabilities (30%) for 80F+.  However, looking at raw
deterministic models and given downsloping I wouldn`t be surprised
to see forecast highs trending up for the weekend as we get closer.
Either way, temperatures will be well above average.

We will see the chance for precipitation come back into the forecast
starting Friday as shortwaves move around the top of the ridge and
low level moisture and instability increased over the area. The GFS
sets up a frontal boundary over Lake Superior on Friday into
Saturday with showers over the northern U.P. Other deterministic
models have the frontal boundary further north keeping most of the
precipitation north of the area. The NBM generally has 20 to 40%
PoPs Friday through the weekend. Instability could be sufficient for
at least a few thunderstorms.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 123 AM EDT Tue Sep 30 2025

Predominantly VFR conditions are expected during the 6Z TAF period
as high pressure extends overhead. Where this could deviate a bit is
potential BR early this morning. Best chances for periods of MVFR
vis to develop ahead of sunrise are at SAW, but low chances (10-25%)
are noted at both IWD/CMX. That said, the dry antecedent airmass
should help limit coverage and prevent significant vis restrictions
with any BR. Otherwise variable winds increase out of the E to SE
this morning with gusts up to around 20 kts anticipated at CMX today.

&&

.MARINE...
Issued at 202 PM EDT Mon Sep 29 2025

Calm S to SW winds prevail this evening ahead of a backdoor cold
front that slides through tonight, veering winds to the N to NE
tonight before upticking to 15-25 kts by sunrise tomorrow morning,
persisting through the afternoon mainly across the western arm of
the lake and around the Keweenaw Peninsula. Winds fall below 20 kts
Tuesday night before veering S to SE Wednesday and becoming gusts to
25 kts again. These gusty southerly winds persist through the late
week.

&&

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

&&

$$

DISCUSSION...NL
AVIATION...Jablonski
MARINE...BW