531
FXUS63 KMQT 040508
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
108 AM EDT Sat Oct 4 2025

.KEY MESSAGES...

- Marine Dense Fog expected over central Lake Superior the rest
  of this afternoon to tonight. A Dense Fog Advisory has been
  issued.

- Spotty showers and storms linger throughout the daytime hours
  today before we dry out again for the weekend.

- Unseasonable warmth continues to this weekend with daytime
  highs 15-20 degrees above normal on Saturday. Max high
  temperature records could be broken across several spots this
  weekend.

- Warm, breezy, and dry weather may lead to limited fire weather
  conditions this weekend.

- Southerly gales are possible across Lake Superior Sunday
  afternoon into Sunday evening.

&&

.DISCUSSION...
Issued at 317 PM EDT Fri Oct 3 2025

As weak warm air advection returns to the area from the south-
southwest this afternoon, moisture-rich air with some help the lake
breeze boundaries moving in have allowed some isolated showers and
thunderstorms to develop across the U.P. this afternoon behind the
`cold front` that left earlier today. With winds being lighter today
than yesterday, no fire weather concerns are expected this
afternoon, even though high temperatures are still projected to get
into the 70s to lower-80s this afternoon across Upper Michigan. Once
the sun sets and the diurnal heating goes away, expect the last of
the showers and storms to dwindle away and end across the U.P. this
evening. While drier air begins to advect into the area from the
south tonight into Saturday, we could see some fog develop over the
central U.P. tonight depending on how much (if any) rainfall
occurs); although most spots are shouldn`t see all that much (a
tenth of an inch or less), areas under the heaviest showers and
storms could see a wetting rainfall (0.10-0.25+ inch) this afternoon
and thus some patchy fog tonight; the area that has the greatest
chance for a wetting rainfall and thus patchy fog is the south
central.

Moving into Saturday and even Sunday, expect even warmer
temperatures that what we`re feeling today, with record-tying or
breaking highs expected on Saturday across the entire area and
potentially even into Sunday too as a low pressure system lifts from
the Plains into northwestern Ontario. As this occurs, expect the
winds to pick up from the south across the region, gusting up to 30+
mph at times Saturday and potentially even over 40 mph at times on
Sunday. While min RHs are projected to remain above 30%, given that
temperatures will be 15 to 20 degrees above normal, the strong
winds, and the lack of recent rainfall across most of the area,
elevated fire weather concerns cannot be ruled out across large
portions of Upper Michigan for this weekend at this time; expect
highs Saturday to soar into the 80s, with some of the downslopes
near Lake Superior like Ontonagon potentially flirting with 90(!)
degrees for a high. While temperatures won`t be as warm on Sunday,
highs in the upper 70s to lower 80s are still expected.

Eventually the cold front of the aforementioned low moves through
the region late Sunday to Monday. While there is a low (~20%) chance
that we could see some showers and storms along and just ahead of
the front, the best chance for rainfall looks to be just south and
east of the U.P. on Monday. Thus, the best chance for seeing
rainfall looks to happen over the eastern half on Monday when the
cold front is leaving the area and high pressure is quickly moving
in from the west. Expect the windy conditions along and immediately
behind the front to calm down rather fast Sunday night into Monday
morning due to the rapidly approaching high pressure. In addition,
temperatures are expected to be much more normal by Monday, with
highs only expected to be in the upper 50s to mid 60s (warmest in
the south central and east). The near-normal temperatures are
expected to continue through to the middle of next week as flow
becomes more zonal Monday into Tuesday. Another shortwave low
dropping down from Canada could bring some lake effect rain showers
to the U.P. come late Tuesday into Wednesday. However, with medium
range guidance increasing high pressure at the sfc in conjunction
with the cold air advection with the low, I`m beginning to think
that we may just see nothing more than stronger winds and cooler
temperatures for the middle of next week. Expect a slight warming
trend for late next week as another system could impact the area to
end the forecast period.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 108 AM EDT Sat Oct 4 2025

VFR conditions will prevail through the TAF period. Expect light
winds through the early morning hours. Gusty southerly winds are
expected to pick up Saturday afternoon and will continue through the
end of the TAF period.

&&

.MARINE...
Issued at 326 PM EDT Fri Oct 3 2025

Light winds of around 20 knots or less continue over the lake this
afternoon into this evening as weak high pressure ridging scoots
through the area. In addition, some dense marine fog is being seen
across the central lake, with guidance showing it persisting into
the overnight hours (thus a Dense Fog Advisory has been hoisted for
the north central lake until 6z tonight). However, as a troughing
pattern begins to move into northwestern Ontario Saturday with a low
lifting from the Plains into northern Ontario Sunday, expect the
winds to pick up from the south and for the fog to vanish by the
morning hours, getting up to 20 to 30 knots by Saturday evening and
increasing to 25 to a few gale force gusts up to 35 knots by Sunday
morning. Ahead of and immediately behind a cold front passing
through the lake late Sunday, south to southwest gales up to 40
knots could potentially occur, with the strongest winds expected
near the Keweenaw, near Isle Royale, and the eastern open waters. As
of the time of this writing, the chances for low-end (35 knot) gales
or greater are around 30 to 70%, with the highest chance for gales
over the eastern open lake. In addition to the winds, an isolated
thunderstorm or two cannot be ruled out, but chances for
precipitation are low (~20%) at this time. The exception is over the
eastern lake where chances increase to around 50% as some diurnal
heating could help convection develop Monday.

Once the cold front passes, expect winds to rapidly weaken, becoming
generally 20 knots or less again by Monday afternoon. Westerly zonal
flow from Monday into Tuesday could allow winds to pick up to 20 to
25 knots between the Keweenaw and Isle Royale Monday night into
Tuesday before another shortwave dropping a cold front through the
lake sometime Tuesday/Tuesday evening brings west to northwest winds
of 20 to 30 knots back over the lake.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from Sunday afternoon through late Sunday night for
     LSZ162-242>250-263>266.

  Dense Fog Advisory until 2 AM EDT early this morning for
     LSZ263-264.

Lake Michigan...
None.

&&

$$

DISCUSSION...TAP
AVIATION...RM
MARINE...TAP