243
FXUS63 KMQT 181136
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
736 AM EDT Sat Oct 18 2025

.KEY MESSAGES...

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

- Rain returns Monday night through the middle of next week.
  Expect breezy conditions on Tuesday. North to northwest gales
  of 35 to 40 knots are possible over Lake Superior on Tuesday.

&&

.DISCUSSION...
Issued at 334 AM EDT Sat Oct 18 2025

While the last of the rain showers associated with an initial cold
front ends over the eastern U.P. this morning, expect clearing skies
over the rest of the area through this morning ahead of an
approaching secondary cold front dropping in from the west later
this evening. Most spots over the past 24 hours or so have seen
around a few hundreths to tenths of an inch of liquid, which hasn`t
done too much to alleviate drought concerns. However, the greatest
rainfall indicated by radar occurred in Delta and southern
Schoolcraft counties, where up to an inch or more fell in spots.
While the rain showers have practically all but wrapped up over
there as of the time of this writing, the rainfall that has fallen
over there will help to put a serious dent in the D0 drought
conditions that recently appeared.

Moving into the daylight hours today, expect generally light
southwesterly winds, with remnant warm air and sunny skies allowing
highs to get back into the 60s to potentially even around 70 in the
south central and east. As a shortwave low lifts from the Mid-
Mississippi Valley through Lower Michigan to James Bay tonight
through Sunday, rain showers start to move back into the area this
evening. While there is still a chance for rain showers over the
west tonight (30 to 50% chance), more of the medium to mesoscale
range guidance though has shifted the range of the rain showers
further east (mostly starting over the central or east) as the track
of the low is now expected to generally run through Lower Michigan
into Saginaw Bay and Lake Huron Sunday morning. Should this occur,
the western half of the U.P. may miss out on rain showers entirely
Saturday night through Sunday. With cold air advection behind the
shortwave low bringing 850mb temperatures of around 0C across the
U.P., we could see some weak lake enhanced/effect rain showers
develop over the northwest wind belts, mainly the east half late
Sunday. However, the chances for this happening are 10 to 30%
(highest over the east), and this looks to end fairly quickly
(Sunday evening) as weak high pressure ridging moves in Sunday night
into Monday morning.

While more seasonable temperatures are expected from Sunday onwards
behind the secondary cold front, the drier weather brought on by the
shortwave ridging looks to leave the U.P. by late Monday afternoon
into Monday evening as troughing over the Plains conglomerates
and coalesces into a stacked low over the Upper Great Lakes by
Tuesday. This brings rain back over the Upper Peninsula Monday
afternoon through Tuesday. As the low elongates over the Upper
Great Lakes towards James Bay late Tuesday, expect to see a
transition to lake enhanced rain showers over the north wind
belts. With shortwaves rotating around the low aiding in
bringing cold air advection and 850mb temperatures down to -4C
across the region, we could see lake effect rain showers
continue through the middle of next week until the end of the
work week; in addition, while no accumulations are expected,
there may be a few snowflakes that mix in with the lake effect
rainfall Wednesday and Thursday as temperatures are projected to
trend to below normal (highs in the mid to upper 40s and lows
around 30F in the interior areas). With robust cold air
advection cycling over the Upper Great Lakes, expect gusty north
to northwesterly winds Tuesday and Tuesday evening. Troughing
and lake effect rain showers look to continue across our area
until late in the work week when ridging returns and brings
calmer weather back to Upper Michigan.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 735 AM EDT Sat Oct 18 2025

VFR expected for most of Upper Michigan through the period as
showers wind down across the east this morning in the wake of a
departing cold front. Light winds give way to WNW winds around 8-10
kt at the terminals this afternoon. Will carry PROB30 at IWD and CMX
near the end of the period as a few showers may develop across the
west 03-06z Sun. Focus shifts to the eastern half after 06z Sun as a
low tracking north across Lower Michigan into Lake Huron brings
rain, potentially making it as far west as SAW by Sunday morning.

&&

.MARINE...
Issued at 334 AM EDT Sat Oct 18 2025

As southwest winds weaken back down to 20 knots or less this morning
behind a cold front, expect them to remain over Lake Superior until
late tonight/early Sunday morning when a shortwave low lifting from
the Mid-Mississippi Valley moves through the Lower Peninsula into
Lake Huron; this causes winds to increase from the north-northwest
to 20 to 30 knots by Sunday morning, with the winds potentially
increasing to northwesterly gales of 35 knots over the eastern lake
by the afternoon hours as the shortwave low lifts to the east of
Drummond Island towards James Bay. While my confidence in the gales
is not quite as high as the previous shift, with model guidance
soundings suggesting we are able to mix down gale force gusts
up to 35 knots from time to time and the 18z REFS suggesting a
50 to 60% chance for gales, decided to keep the Gale Watch going
for the eastern third of the lake from 11 AM EDT Sunday to 11
PM EDT Monday. As the cold air advection behind the low ceases
and weak high pressure ridging moves back into the region Sunday
night into Monday morning, expect the winds to calm back down
to 20 knots or less again over Lake Superior before dawn Monday
morning.

Don`t expect the light winds to last all that long over Lake
Superior on Monday as a troughing pattern over the Plains
conglomerates and coalesces into a stacked low pressure over
the Upper Great Lakes by Tuesday. As this occurs, expect the
winds to intensify over Lake Superior from the southeast late in
the day Monday to 20 to 25 knots. As the low develops and
passes nearby the lake, expect the winds to shift to the
north/northwest and potentially invigorate to gales of 35 to 40
knots on Tuesday (40 to 50% chance according to the LREF and
NBM). It`s advised, then, that mariners keep an eye on the
forecast and keep up with the latest updates for Lake Superior
if they are traversing the waters Monday night through Tuesday
given the potential for dangerous winds and waves. While the
winds look to weaken a little bit Tuesday night as the strongest
punch of cold air advection leaves the area, we could still see
gusty winds impact Lake Superior the rest of the mid week as
shortwave lows rotate over the region and cycle some shots of
cold air advection back across the region.

&&

.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...TAP
AVIATION...CB
MARINE...TAP