145
FXUS63 KMQT 172325
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
725 PM EDT Fri Oct 17 2025

.KEY MESSAGES...

- Rain chances return late today in the west, then rain becomes
  more widespread this evening and tonight across the east
  half.

- Rain and breezy winds are expected across eastern Lake
  Superior and Upper Michigan Sunday. A Gale Watch has been
  hoisted for eastern Lake Superior.

- Rain returns Monday night through the middle of next week.
  Expect breezy conditions on Tuesday.

&&

.DISCUSSION...
Issued at 258 PM EDT Fri Oct 17 2025

After this morning`s warm front and rain, Upper Michigan has been
parked within the warm sector of a closed and near-vertically
stacked low positioned near Lake Winnipeg. Within this region,
southwesterly flow has warmed the region into the 60s so far.
Upstream, a cold front is analyzed extending south of the system`s
triple point into Minnesota and into the east-central Plains. Rain
ahead of the front this morning was generally light and fast moving
toward the northeast over western Lake Superior, the Arrowhead, and
northwestern Wisconsin. As the rest of today progresses, the front
will inch into Upper Michigan, likely resulting in additional shower
development. Enough elevated instability will be in place to support
some weak thunderstorm activity by evening. As the front pushes
eastward this evening, rain will end in the west and then become
more widespread in the east in part due to the elevated instability,
but also because increasing synoptic forcing from an associated jet
streak aloft. Rain will gradually end in the east Saturday morning,
followed by a mostly dry day for the forecast area save for isolated
or scattered passing rain showers in the east. Overnight lows
tonight fall into the 40s west and low to mid 50s east, Keweenaw,
and by the lakeshores. Daytime highs Saturday climb into the mid 60s
to low 70s.

Colder air will eventually pour into the area Saturday evening/night
behind a secondary cold front. The front may support rain along the
boundary while a shortwave aloft takes on a negative tilt in
response to an amplifying jet streak at 300mb over the central
Mississippi River Valley, resulting in a surface low developing near
Chicago. There continues to be spatial differences in ensemble
clustering, but the general idea is for the low to lift northeast
through Lower Michigan to near or east of Drummond Island by Sunday
afternoon while deepening to around 989mb, then to near James Bay by
Sunday evening. The intensifying nature of the system and increasing
cold air aloft will result in rain become widespread over eastern
Upper Michigan and winds increasing through the day. Wind speeds of
near 25-30 mph will be common across the east half near the
lakeshores of Lake Superior per LREF/NBM 4.2. Inland areas should
also expect gusty winds through the day to at least 20mph; should
the surface low end up being further west though, winds closer to 30
mph may be widespread across the east half. QPF in the various
deterministic solutions varies thanks to the spatial disparities,
but the GEFS and ECS suggesting probabilities for >1 inch increasing
above 30% in and east of Luce County looks realistic. Rainfall ends
Sunday night as a ridge builds into the region. Daytime highs Sunday
look to peak in the 50s and bottom out in the low 40s to low 30s,
coolest interior west.

Dry conditions prevail into at least Monday afternoon, potentially
into the evening. An amplifying shortwave is expected to press east
or eastsoutheast through south-central Canada/northern CONUS Sunday
night while a surface low organizes in northeastern Wyoming. As
Monday progresses, the surface low will lift into northeast North
Dakota or Minnesota, eventually filing into the Upper Great Lakes
Monday night through Tuesday evening/night. Considering its still a
ways out, there is fairly good clustering in the various ensemble
systems with this evolution, which gives me higher confidence in
widespread rain across the forecast area. The pressure gradient
forces and cold air advection suggested by all deterministic packages
also suggests breezy to windy conditions as well, but confidence is
lower in this given the more nebulous consensus in the depth of the
system and magnitude of these parameters. Weak ridging returns
Wednesday with another system on its heels in the Thursday/Friday
time frame.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 725 PM EDT Fri Oct 17 2025

VFR conditions prevail at all terminals throughout the forecast
period. However, with a passing cold front, a few showers will be
possible at SAW over the next few hours. That said, impacts should
be limited. Meanwhile, breezy southwesterly winds will persist into
tonight at CMX, with gusts to around 20-25kts. Some 20kt gusts will
also be possible through the first half of the night at SAW. Expect
partly cloudy and quiet weather into Saturday before clouds spread
in again late in the day.

&&

.MARINE...
Issued at 258 PM EDT Fri Oct 17 2025

Southerly winds of 15-30 kts have been observed across Lake Superior
today, with the higher end reports coming from high platforms like
STKM4. Winds may increase this afternoon and evening ahead of and
behind a passing cold front, but generally remain 25kts or less
tonight. By Saturday, light winds below 20kts are expected. A
passing cold front Saturday night will help elevate winds back to
near 25kts across the west half and be the focus for a developing
low pressure near Chicago. This low will lift northeast along the
front as it deepens through the day Sunday, resulting a tight
pressure gradient developing around the low. There are still
questions about the exact track, but the model consensus is that it
should lift to near Drummond Island or just east of there by Sunday
afternoon, then to James Bay Sunday evening/night. With the
increasing cold air spilling into the region, at least low end gales
look good for the east half of Lake Superior. This is further
supported by deterministic guidance`s suggestions of 35-45kt 925-
850mb winds. Opted to go ahead and issue a Gale Watch with this
forecast package for this potential.

Winds are expected to lighten Sunday night back below 20kts. The
next system begins moving into the region Monday/Tuesday. The
signals are there for another gale, perhaps high end if the track is
right. Given the uncertainty in the track and thus where all the key
conditions would line up, I`m currently not confident in anything
more than low end gales. Recommend those transiting Lake Superior
Monday night/Tuesday to monitor future forecasts.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from Sunday morning through Sunday evening for
     LSZ249>251-266-267.

Lake Michigan...
None.

&&

$$

DISCUSSION...JTP
AVIATION...LC
MARINE...JTP