215
FXUS63 KMQT 161734
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
134 PM EDT Wed Sep 16 2026

.KEY MESSAGES...

- Seasonably mild highs of 65-75 today and Thursday will cool a bit
with mainly 60s expected Friday into the weekend.

- Rain becomes likely (>60% chance) for the south half of the UP
Friday afternoon into at least Saturday morning, where there is a
moderate chance (40-60%) of amounts exceeding an inch. There is
uncertainty in how far north the precipitation will reach.

&&

.DISCUSSION...
Issued at 1249 PM EDT Wed Sep 16 2026

Midlevel flow pattern is dominated by 600 dam high over the southern
Appalachians. A few areas of enhanced moisture are noted along the
N/NW periphery of this circulation, although none are resulting in
impacts to the sensible weather over the UP at this time. This is
due to high pressure building into Lake Superior/the UP from the
northwest, leading to a seasonable and pleasant day. A northern
stream midlevel trough is pushing eastward across the southern
Prairie Provinces, and will continue to do so tonight. This will
shift the surface high east overnight, and teaming up with some of
the midlevel moisture noted over the central/northern Plains, brings
the potential for a few light showers overnight. This potential is
brief and non-impactful, as time-height sections indicate the
midlevel moisture exiting once saturation occurs at lower levels.

Midlevel ridging, as an extension of the 600 dam high, will build
over the northern Plains Thursday before flattening out on Friday
due to vort maxes ejecting eastward from a western US trough. This
will result in another surface high building from the northwest
Thursday, leading to another pleasant and seasonably mild day with
highs of 65-75.

By Friday, surface low associated with the ejecting vort maxes will
develop over the central Plains and move slowly eastward through
Saturday. Meanwhile, surface high will remain anchored over Ontario
while slowly drifting eastward. Seasonably strong 30-40kt southerly
LLJ with Gulf connections will be found over the Plains, resulting
in healthy poleward theta-e advection. These ingredients point to a
prolonged heavy rain potential due to overrunning at the nose of the
LLJ, but also a sharp gradient in the precipitation shield due to
the dry airmass associated with the high. There is still
considerable uncertainty in the track of the relevant features and
the swath of the heaviest rainfall. In a system-relative sense, the
heaviest swath and resulting flooding concerns will be south of the
UP, but there is still potential for beneficial rainfall amounts to
alleviate existing drought conditions over roughly the southern half
of the UP, where probabilities of exceeding an inch of rain are 40-
60 percent. Some higher end totals cannot be totally ruled out, with
the 90pctl of the NBM showing 2.5-3.5 inch amounts; however, the
flip side of this is the 10pctl is less than 0.25 inches. The window
for this rain is Friday afternoon into Saturday morning, although
there is moderate potential for some showers to linger into Saturday
afternoon. A dry forecast is favored by Sunday as another high
builds in from the north. Highs will cool back into the 60s for the
Friday into the weekend period.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 133 PM EDT Wed Sep 16 2026

VFR conditions will prevail at all three sites this period. Winds
will be light, shifting slowly from roughly north to roughly south
over the next 12 hours. A transient boundary on the back end of
today`s high pressure will generate increased cloud cover and low
precip chances tonight. LAMP guidance shows all sites with <15%
chances of VLIFR ceilings and visibility during this time. Though
tonight`s light winds favor fog, with the forecast trend of
decreasing precip chances to less than 15% at all sites, low-level
moisture is unlikely to be high enough to catalyze fog
formation. Thus mention of fog and precip omitted.

&&

.MARINE...
Issued at 1249 PM EDT Wed Sep 16 2026

High pressure keeps winds below 20 kt through Thursday night. Friday
and Saturday, low pressure passing by to the south combined with a
high to the north will result in prolonged northeasterly flow into
the western arm of Lake Superior, with winds increasing to 20-30 kt
and waves of 3-4 feet. A stronger high building to the north on
Sunday looks to expand coverage of 20-30 kt winds to much of the
southern half of Lake Superior, with probabilities of gales near 40%
over the western arm. Waves increase to near 3 feet over northern
Lake Michigan and Green Bay on Saturday as well due to prolonged
easterly flow approaching 20 kt.

&&

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

&&

$$

DISCUSSION...Thompson
AVIATION...RE
MARINE...Thompson