Keweenaw Bay, Michigan Weather Forecast Discussion

663
FXUS63 KMQT 071937
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
337 PM EDT Sun Sep 7 2025
.KEY MESSAGES...
- Patchy frost is possible across the interior-western UP tonight.
- Dry weather persists through Monday before a warm front brings
showers and thunderstorms late into Tuesday.
- A warming trend is set for this week with daytime high temps
climbing back into the 60s to low 70s and overnight lows averaging
near 50.
&&
.SHORT TERM /THROUGH MONDAY/...
Issued at 336 PM EDT Sun Sep 7 2025
Afternoon RAP analysis and GOES water vapor reveal deep midlevel
troughing over the Lower Great Lakes with a subtle embedded
shortwave dropping southeast of the UP. Meanwhile, a midlevel ridge
continues to build over the western CONUS, supporting sprawling
surface high pressure over the Midwest that is inducing ridging into
our area behind the aforementioned wave. Visible satellite still
shows plenty of lake clouds over the area in spite of dwindling lake
effect rain showers, but as winds back more to the W/SW the rest of
today with the ridge building in, expect lake clouds to diminish
from west to east the rest of today into the evening. Still, some
high cloud cover may continue to spill into the area another vort-
max dropping through Ontario this evening into tonight.
Meanwhile, temperatures remain chilly with most of the area only
peaking in the lower/mid 50s. Winds are staying elevated as well,
particularly across the eastern half of the UP given a longer fetch
off of Superior and a tighter pressure gradient there. However, look
for winds to fall back as we head into the evening hours.
Temperatures across most of the area drop into the mid/upper 30s
tonight, and in the mid 40s near the shorelines of the Great Lakes.
There is a potential for some patchy frost to develop across the
interior-western UP late tonight, but confidence remains too low for
an advisory as cloud cover may prove a limiting factor in coverage
of frost.
Dry weather persists for most of Monday as the surface high shifts
into the Lower Midwest and another trough begins to drop out of the
Canadian Prairies. Strengthening southerly flow aloft ahead of the
approaching shortwave will pump in a warmer airmass, with
temperatures reaching well into the 60s for much of the UP.
Otherwise, expect increasing clouds with chances for showers and
perhaps a few rumbles of thunder finally reaching the far western UP
later in the evening. Winds turn breezy again during the afternoon,
with gusts to around 20mph across most of the area.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 336 PM EDT Sun Sep 7 2025
Dry weather gives way to a quick period of wet weather beginning
Monday night as the shortwave drops out of the Canadian Prairies. An
initial batch of PoPs kicks off across the western UP Monday night a
the warm front begins to lift into the UP and a strengthening LLJ
becomes directed towards the area. Another batch of PoPs will be
right on its heels as the cold front sweeps through during the
daytime hours of Tuesday. With weak instability, some thunder will
be possible Monday night through Tuesday, though modest shear will
limit concerns for strong/severe convection at this point. Guidance
continues to suggest healthy rainfall amounts upwards of around 0.30-
0.60" area wide by the time showers exit the eastern UP Tuesday
evening, with the 75th to 90th percentile of 24hr QPF highlighting
portions of the central UP receiving near an inch, which may be
possible where elevated thunderstorms persist. Additionally, the S
to SW oriented 30-40kt LLJ over the area late Monday into Tuesday
points towards gusty conditions for the typical downsloping
locations of the central and eastern UP, as well as hazardous marine
weather in northern Lake Michigan and eastern Lake Superior.
Ensembles continue to highlight a 20-40% chance for 35 kt gusts in
the aforementioned areas Tuesday morning and afternoon. This may be
underdone as previous WAA high wind events have overachieved along
the eastern shores of Lake Superior and off of the Keweenaw
Peninsula.
By midweek, deepening midlevel low pressure will be spinning over
the Pacific Northwest and Quebec, with ridging recovering atop the
central CONUS. This will keep the U.P under a northwest to westerly
upper level flow through the latter half of the week while surface
high pressure expands over the region, favoring a return to mainly
dry weather for the rest of the work week. Ridging breaks down into
next weekend with PoPs returning to the forecast. Temperatures trend
warmer this coming week, with highs in the 60s to lower 70s Monday
onwards.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 138 PM EDT Sun Sep 7 2025
Primarily VFR conditions are expected during the 18Z TAF period as
high pressure takes hold over the Great Lakes. W to NW winds taper
off through this evening, increasing out of the SW to S around 10-12
kts by Mon afternoon.
&&
.MARINE...
Issued at 336 PM EDT Sun Sep 7 2025
NW winds continue to gust to around 20kts in the eastern half of
the lake, but winds to the west are already backing over to the
southwest. Winds shift over to the W/SW in the eastern half of the
lake this evening. Wind gusts briefly fall back to around 15-20kts
early this evening, but then more persistent gusts around 20kts are
expected tonight into early Monday across the western half of the
lake - mainly between the Keweenaw and Isle Royale. Winds fall below
20kts Monday morning. Then, a shortwave low moving through the lake
brings southerly winds of 20 to 25 knots back over the eastern lake
Monday night into early Tuesday; a few gusts up to 30 knots cannot
be ruled out at this time, and given the strong LLJ overhead (up to
45 knots in some models), there is a 30% chance that the southern
shoreline over the eastern lake could see a gale-force gust or two
up to 35 knots. In addition to the gustier conditions, some showers
and storms associated with the shortwave low look to move over Lake
Superior late Monday through Tuesday; no severe weather is expected
as storms look to remain elevated. Once the shortwave low passes
Tuesday morning, expect the winds to die-down to 20 knots or less
again by the afternoon hours, with winds remaining light to the end
of the work-week as high pressure ridging slowly makes its way
through the Upper Great Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement until 8 PM EDT this evening for MIZ006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...LC
LONG TERM...LC
AVIATION...Jablonski
MARINE...LC

NWS MQT Office Area Forecast Discussion