560
FXUS63 KMQT 271951
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
351 PM EDT Wed Aug 27 2025

.KEY MESSAGES...

- Scattered showers and a few thunderstorms continue across the
  UP tonight, clearing southeast by Thursday morning.

- Gusty westerly to southwesterly winds 20-30 kts persist this
  evening in western Lake Superior and the Keweenaw Peninsula
  with occasional gale force gusts to 35 kts.

- Winds turn N to NE behind a cold front tonight, leading to
  hazardous swimming and boating conditions on Lake Superior
  Thursday.

- Frost is likely Thursday night across portions of the
  interior.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 349 PM EDT Wed Aug 27 2025

GOES Satellite imagery and RAP analysis reveal troughing atop much
of the eastern CONUS with a few embedded shortwaves within the
longwave feature. One of these waves is currently diving southeast
through N-central Ontario. The attendant mid-level confluence
overhead the northern Great Lakes has led to scattered showers and a
few thunderstorms this afternoon across the UP, though t-storm
activity has been mainly confined to the western arm of Lake
Superior and a bit further upstream in northern MN where better
(albeit still meager) instability lies. Additionally, gusty W to WSW
winds have been the rule, largely in the Keweenaw where winds down
the long fetch of the Superior and efficient mixing into 30-40 kts
gusts aloft have been able to bring down a few 40 mph gusts at CMX.

Tonight, the trough axis moves through the Upper Lakes, sending a
stout cold front across Lake Superior and quickly veering winds to
the N-NE. Reinforced CAA over the lake will make for a windy
Thursday on the Lake Superior shoreline with frequent gusts 20-25
kts. Wave heights building 3-6 ft will make for hazardous boating
conditions. Otherwise, increasing sfc high pressure and subsidence
drying via ridging aloft will help to scatter out low level
moisture, leading to increasing sunny skies though the afternoon.
Cool northerly flow will keep daytime highs in the 50s to low 60s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 349 PM EDT Wed Aug 27 2025

On the western flank of the shortwave diving into the NE US, a cool
airmass will descend into Upper Michigan Thursday alongside a
surface high and dry air. The cool and dry airmass, characterized by
850mb temps falling to ~2-5C and PWATS near or below 0.5 inches,
will support effective radiational cooling. Near Lake Superior and
by the lakeshore of Menominee County, overnight lows may fall into
the 40s while the rest of the forecast area falls into the 30s.
Given the light rainfall today and that previously anticipated
cooler nights yielded many RAWS sites dipping into the low 30s,
suspect frost will be a bigger concern Thursday night. 50th
percentile statistics suggest widespread mid to low 30s in the
interior west while, what appears to be a more likely scenario given
the pattern, the 25th to 10th percentile yields widespread low 30s
including a few patches of upper 20s. Time-height profiles across
the interior west suggest varying degrees of low level cloud cover
hanging around Thursday night into Friday morning, which may stymie
efficient radiational cooling, thus keep temperatures closer to or
above the 50th percentile of NBM guidance and lower frost potential.
Regardless, with the potential for frost, those aware from the
lakeshores with sensitive vegetation may want to consider protective
measures.

Otherwise, daytime temperatures Thursday favor upper 50s to low 60s.
A slightly warmer airmass looks to settle into the area afterwards
where 60s Friday increase to low to mid 70s Saturday and Sunday.
Overnight lows, save for Thursday night, will largely fall into the
40s interior and 50s lakeside.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 128 PM EDT Wed Aug 27 2025

Scattered light rain showers persist this afternoon and evening as a
cold front swings down from the north. Ahead of this front, gusty W
to SW winds upwards of 25-30 kts are being observed at CMX.
Elsewhere, winds remain sub 15 kts but may push 15-20 before
tapering down this evening. Also of note, a few GOES satellite
imagery has detected a few stray lightning flashes/strikes near Isle
Royale and further upstream into far N MN. Not anticipating any
thunderstorms at any TAF sites tonight. As showers continue south
and east late tonight into the morning hours, VFR conditions begin
to deteriorate to near IFR at SAW/IWD. Low cigs should begin to lift
in the morning post cold front as drier air filters into the region.

&&

.MARINE...
Issued at 349 PM EDT Wed Aug 27 2025

A low pressure trough and associated cold front dropping down from
Ontario, in combination with high pressure just to our south, is
leading to a tight pressure gradient over the lake this afternoon.
So far, SW wind gusts to around 20-30kts are most common, though
some gale-force gusts up to 35kts have been observed at times across
the western half of the lake generally between the Keweenaw and Isle
Royale. Meanwhile, showers and storms continue to move across the
lake ahead o the front. After the front moves through later this
evening, winds shift to the northeast behind the front which then
persist into early Friday. Winds may briefly fall below 20kts the
first half of the night, but then pick up to around 20-30kts across
most of the lake late tonight into Thursday as high pressure begins
to build into the region. Winds lighten below 20kts Thursday evening
and through the weekend. These light winds look to hold through at
least Tuesday.

&&

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

&&

$$

SHORT TERM...BW
LONG TERM...BW
AVIATION...BW
MARINE...LC