656
FXUS63 KMQT 291934
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
334 PM EDT Fri Aug 29 2025

.KEY MESSAGES...

- Patchy dense fog is possible tonight across interior western
  and central portions of Upper Michigan.

- A calm and pleasant Labor Day weekend is in store!

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 332 PM EDT Fri Aug 29 2025

Afternoon RAP analysis has a 1022mb high centered over the Upper
Great Lakes with a mid level trough over Quebec extending some
cyclonic flow aloft. Another cooler than normal day is ongoing under
NW flow with temps in the upper 50s to 60s under a diurnal-cu field
over the S-Central and E, mostly clear elsewhere.

With mostly clear skies, high pressure, and calm winds continuing
through tonight, cool temps are expected in the 40s to low 50s; a
few typical low lying spots may settle into the 30s. Some patchy FG
development is expected by Sat morning given the strong inversion
set up from radiative cooling accompanied by low level moisture.
Some dense fog is possible late tonight interior W and central (~20-
45% chance).

The warming trend continues through Sat with N flow weakening and a
warmer airmass slowly meandering in from the W. Highs will be in the
upper 60s to mid 70s with temps lowering into the mid 40s to upper
50s by Sun morning. A cold front over N Ontario remains well to the
N, but some -SHRA might advect out over W Lake Superior into Sat
night (10% chance or lower...mainly only noted in the NAMNest).
Otherwise dry weather persists with light winds around 10 mph or
less during the day becoming calm overnight. Additional patchy FG is
possible Sat night into Sun morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 332 PM EDT Fri Aug 29 2025

The latter half of the holiday weekend will be influenced by the mid
level ridge setting up over the Great Lakes with associated high
pressure strengthening at the sfc near S Ontario/Quebec. Shortwave
energy stretching out over the Plains and Mid MS Valley limits
moisture advection into the region, but gradual/weak SW flow will
bring warmer temps with highs back in the 70s and lows in the 50s. A
few diurnal -SHRA and rumbles of thunder can`t be ruled out (mainly
on Labor Day over N-Central and W), but impacts should be low given
limited shear and inconsistent instability in model guidance.
Current PoPs are less than 20% for Labor Day. For the most part,
this provides pleasant weather with light winds and plenty of
sunshine to close out the holiday period.

Attention then turns to a trough upstream over central Canada on
Tue. This trough digs S over Manitoba/Ontario Tue and Tue night,
settling into the Upper Great Lakes on Wed. From here, differences
in positioning and propagation grow into the weekend, however the
general consensus is for a few embedded wrap around shortwaves to
pass over the region as this trough slowly makes its way toward
Quebec for Sun. This sends a sfc trough and cold front across our
region Tue night and Wed, a cold airmass over the Great Lakes for
late next week, and likely another cold front and shortwave pair on
Fri. SHRA and maybe some rumbles of thunder accompany the first cold
front round late in the day Tue into Wed, but instability is low (a
few hundred j/kg of MUCAPE at best). 850mb temps quickly fall near
0C for Wed - Thu, bringing back lake effect -SHRA. A secondary cold
front toward the end of next week brings the last hurrah of PoPs in
the fcst before high pressure briefly returns for the weekend to
gradually bring back drier weather. This colder pattern brings temps
back below normal with highs only in the 50s to low 60s and lows in
the 30s and 40s. An uptick in N becoming W winds is also expected in
the latter part of next week with gusts in the Keweenaw in the 20-30
mph range Wed/Thu.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 149 PM EDT Fri Aug 29 2025

Primarily VFR conditions are expected during the 18Z TAF period as
high pressure becomes centered over the Great Lakes. Where this may not be
the case is patchy BR/FG late tonight into early Sat, primarily at
SAW/IWD. Confidence is low given probabilities of BR/FG are around
20-45%. However, if development occurs, patchy dense FG down to
IFR/LIFR would impact those respective sites. Opted to continue
mention of MVFR for now at IWD and added it to the SAW TAF. Any
BR/FG should lift around 12-13Z on Sat with only a few mid level
clouds drifting over the UP during the day. Otherwise light winds
mainly remain under 10 kts during the period.

&&

.MARINE...
Issued at 332 PM EDT Fri Aug 29 2025

High pressure residing over the Great Lakes keeps winds below 20 kts
across the lake through the holiday weekend. A cold front and sfc
trough approaching from the NW on Tue increase S to SW winds to 10-
20 kts during the day, strongest winds are expected over the W half
of the lake. Winds quickly veer NW, increasing to 20-30 kts Tue
night as the cold front presses SE across the lake. A cold airmass
overhead midweek continues N becoming W winds in the 20-30 kt range.
Current probabilities for gales to 35 kts are around 25-50%, highest
over the central third of the lake Tue night through Wed afternoon.

&&

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

&&

$$

SHORT TERM...Jablonski
LONG TERM...Jablonski
AVIATION...Jablonski
MARINE...Jablonski