432
FXUS63 KMQT 171829
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
229 PM EDT Thu Sep 17 2026

.KEY MESSAGES...

- Chance of rain (30-50%) for the south half of the U.P. Friday
  afternoon into at least Saturday morning. There is a slight
  chance (~10-25%) of amounts exceeding an half an inch, mostly
  limited to Menominee County south of US-2.

-There is uncertainty in how far north the precipitation will
 reach, but totals are expected to be low if precipitation does
 occur in the northeastern U.P.

-Temperatures are expected to remain at or just below average
 through midweek.

&&

.DISCUSSION...
Issued at 228 PM EDT Thu Sep 17 2026

Latest visible satellite imagery shows cumulus clouds developing
thanks to diurnal heating over the central and western U.P., with
scattered midlevel cloud cover across Lake Superior. The latest
water vapor imagery shows a fairly dry zonally-oriented airmass
across the U.P. and much of the eastern US-CA border, which is
reflective of the generally zonal flow across the area at 500mb.
Lows tonight are expected to fall into the mid to low 40s, which
could result in some patchy fog in the southwestern U.P.

As the 500mb low currently over northern Manitoba continues to
progress eastward this evening, 500mb ridging is expected to build
over central Canada. Combined with the effects of the high pressure
center currently centered over AR, this will result in ridging over
the central US and generally northwesterly upper level flow across
the western Great Lakes region tonight through Friday morning. A
shortwave trough is expected to move across the largescale ridge to
our west tonight, arriving just south of the CWA by Friday afternoon
and bringing our next best chance of rain. The NBM continues to keep
the heaviest rainfall south of the U.P., which is in agreeance with
the latest CAMs guidance. LREF chances for 24-hour rain totals
greater than 0.01 inches between 00z Saturday and 00z Sunday are
between 20-40% for the northern and eastern U.P., and increase to
upwards of 60% for the central southern U.P. Probabilities decrease
significantly with increasing totals, with a 10-25% chance of totals
exceeding 0.5 inches for Menominee County.

On Sunday, a 500mb ridge is expected to build over MN in advance of
an eastward-moving 500mb low currently over northern CA. This ridge
will progress over the area Monday, bringing clearing skies.
Tuesday, the aforementioned low weakens due to the influence of the
ridge as it progresses into our region and split flow develops
around the weakening low and amplifying ridge.At this time, there is
still some uncertainty as to the exact track of this split flow,
however, the U.P. is currently projected to be under generally high
pressure, which would result in dry weather and seasonable
temperatures through midweek.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 143 PM EDT Thu Sep 17 2026

VFR conditions expected through the TAF period as surface high
pressure strengthens over Upper Michigan through Friday. Can`t rule
out some patchy fog in the west tonight, including at KIWD where
there is a ~30% chance for MVFR visibility into early Fri morning.
Winds remain below 10 kt through the period, turning easterly Fri
afternoon ahead of a system passing south through Wisconsin.

&&

.MARINE...
Issued at 228 PM EDT Thu Sep 17 2026

Lake Superior: Tonight, winds remain below 20kts and are expected to
shift from westerly to northerly around 04z Friday. On Friday, winds
are expected to become easterly at up to 20kts. On Saturday, expect
a shift to southeasterly winds slowing to under 15kt for the east,
remaining easterly and up to 20kts in the west, especially the
western arm of Superior, which could see winds exceeding 25 kts near
Duluth. On Sunday, northeasterly winds are expected to reach 20-
30kts in the south and west. Uncertainty remains as to whether winds
will exceed gale conditions in the southern portion of the western
arm, with the latest NBM run projecting around a 30-40% chance of
exceedance. Wave heights are expected to remain below 3ft until
Sunday, when they build up to 3-6ft. For Monday and Tuesday, the
strongest winds (up to 30kts) will remain in the western arm of the
lake, while most areas will see winds at or below 20kts.


Northern Green Bay and Northwestern Lake Michigan: Winds remain
under 15kts and generally northerly until Saturday morning,
when they strengthen to around 15kts and shift to easterly. On
Sunday, northerly winds return, with speeds up to 25kts
possible. On Monday, winds will weaken slightly to around 20kts
and shift easterly, with similar conditions expected to last
through midweek. Wave heights are not expected to exceed 2ft
until Sunday, when they build to 3 ft. 2-3ft waves remain in the
forecast through Tuesday, and reduce to 1-2ft or less
Wednesday.

&&

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

&&

$$

DISCUSSION...LH
AVIATION...CB
MARINE...LH