289
FXUS63 KMQT 170656
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
256 AM EDT Mon Aug 17 2026

.KEY MESSAGES...

- Showers and thunderstorms will be possible (up to 50%) along a
cold front tonight into Tuesday.

- Temperatures will be close to seasonal averages most days through
next week, with highs in the 70s and lows in the 40s and 50s.

&&

.DISCUSSION...
Issued at 256 AM EDT Mon Aug 17 2026

GOES-East Nighttime Microphysics imagery shows just some patches of
low to mid level clouds over the UP now that the previous day`s
showers are all east of the region. Scattered METAR reports of 1/2
mile to 1 mile visibility have been reported, but are not consistent
spatially or temporally, so no advisory is planned, however, will
continue to monitor in case the coverage becomes enough to impact
the Monday morning commute.

Per RAP analysis, the upper air pattern consists of an expansive
500mb high over much of the southern CONUS with deep troughs off of
each coast and one in northern Manitoba. Through Tuesday afternoon,
a 500mb trough will deepen and become a closed low as it swings
along the Hudson Bay shoreline from Manitoba to far northwest
Ontario. Falling 500mb heights ahead of this closed low will lead to
the formation of a surface trough that will once again bring rain
shower chances to the UP tonight. CAMs show some convective activity
in Minnesota and northwest Ontario ongoing at 00Z Tuesday, though
there is significant spread on the continuity of the line of showers
along the front as well as the intensity therein. If convection
survives crossing the lake and reaching the UP, it will be moving
into stable air (HREF mean MUCAPE between 100-250 J/kg), though it
will be a shear-rich environment as HREF mean 0-3km SRH balloons to
100-200 and deep speed shear is present (including the presence of a
100+kt jet at 250mb). Model soundings show meager lapse rates but
plentiful deep moisture (LREF mean PWAT grows to about 1.25 inches,
around the 75th percentile of climatology). Thus, if any
thunderstorms can get going, some heavy rain rates could be
observed, but severe thunderstorms seem unlikely given the timing of
the showers not lining up well with diurnal destabilization and the
best forcing being displaced from the UP. Unfortunately for the
areas of growing drought for the UP, this rainfall does not look to
be widespread, as LREF probabilities of 0.1 inch of rain by 00Z
Wednesday are 20-40% for the west half and 40-65% for the east half.

Another dry spell then kicks off early Wednesday morning through at
least Thursday evening. Models diverge significantly for the late
week period, though the passage of another deep trough from the
northwest looks to be the next mechanism for bringing shower and
thunderstorm chances to the UP late this week into next weekend.
With the continued background northwesterly flow aloft pattern,
temperatures generally remain seasonal with highs in the 70s and
lows in the 50s.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 130 AM EDT Mon Aug 17 2026

Primarily VFR conditions are expected at the TAF sites this period.
Notable exceptions are temporary FG to LIFR at IWD which has already
been observed as well as the approximately 40 percent chance of
at least MVFR visby at SAW with patchy FG this morning. PROB30s
have been introduced to IWD/CMX tonight with an approaching
front, with precip holding off at SAW until closer to 12Z
Tuesday. Winds generally out of the west at 5-10 kt (higher at
CMX) will become southerly tonight ahead of the front.

&&

.MARINE...
Issued at 256 AM EDT Mon Aug 17 2026

Wind gusts around or less than 20 kt on Lake Superior this morning
last through tonight (with the notable exception of southwesterly
wind gusts funneling between Isle Royale and Thunder Bay Monday
afternoon to 20-25 kt). A cold front passing over the lake tonight
into Tuesday will have gusty westerlies for the east-central portion
of the lake to 20- 25 kt for Tuesday afternoon. Winds falling below
20 kt again Tuesday night will remain thus until the next
disturbance arrives late in the week.

&&

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

&&

$$

DISCUSSION...GS
AVIATION...GS
MARINE...GS