556
FXUS63 KMQT 201154
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
754 AM EDT Sun Sep 20 2026

.KEY MESSAGES...

- Light lake-enhanced showers will be possible (~30%) especially
along the terrain of the western and north-central UP this morning.

- Gusty northeast winds will cause hazardous swimming conditions and
rip current risks along Lake Superior today.

- Dry pattern with high pressure sets up through much of next week.
Below-average temperatures expected through Wednesday (including
morning frost potential), giving way to above-normal temperatures
late week.

&&

.DISCUSSION...
Issued at 312 AM EDT Sun Sep 20 2026

Early morning GOES-East Nighttime Microphysics RGB imagery shows a
wide variety of cloud structures, though KMQT radar returns have all
but entirely fallen off entirely. MRMS estimates of rainfall today
have been highly variable, with some locations along the state line
getting no measurable precip, but some locations as far north as
northwest Delta County and southern Marquette County seeing between
0.1 and 0.2 inches. The 500mb pattern currently consists of ridging
over the south-central US and over the West Cost separated by a
cutoff low over Wyoming with building ridging over the Canadian
Prairie. A dry shortwave is noted over northern Ontario by RAP
analysis and water vapor imagery.

Today, a cold front associated with the Ontario trough drops
southeastward over Lake Superior and into the UP. Weak forcing and a
lack of moisture will lead to spotty showers at most with the front
itself. However, the surge of cooler air aloft will cause marginally-
supportive thermodynamic profiles for some lake-enhanced or lake-
effect rainfall, with CAMs showing the orographic forcing of the
western and north-central UP being enough to force weak
precipitation, though QPF will be low. This will also come with some
gustier NE winds, with gusts of 20+ MPH forecast especially along
the Lake Superior shores. This in turn cranks wave heights up to 6
ft within 5 miles of the Lake Superior shoreline, which will
drastically increase the risk of hazardous rip currents and
challenging swimming conditions for those trying to squeeze in a
late-September Sunday beach day at Lake Superior beaches. A Beach
Hazard Statement will be issued before sunrise today, lasting until
sunset. Waves falling below 3 ft by Monday morning will cause the
hazards to wane over at least Alger County, though uncertainty still
persists in whether conditions will relax enough for Marquette
County to not need another Beach Hazard Statement to kick off the
work week. Clearing skies overnight will allow temperatures tonight
to fall to the 30s away from the shores of the Great Lakes. Patchy
frost is currently forecast as there is some uncertainty in the
timing of clearing and how effective radiational cooling will be.
However, if more certainty is granted by the day`s models, a Frost
Advisory may become necessary.

In the wake of the weekend disturbances, the ridging to the north of
the trough amplifies, causing split flow. This results in dominant
surface high pressure establishing over northern Ontario and Quebec
through much of next week, likely bringing an extended period of dry
weather to the UP. The latest NBM keeps us dry until Sunday but even
then, the precipitation signal is not particularly strong. Upstream
ridging aloft results in cooler continental flow aloft, and being on
the south/southwest periphery of a surface high results in cool
easterly to northeasterly flow at the surface off of the Canadian
Shield. This brings cool conditions for the beginning of the week
with a gradual warming trend as the week goes on. For instance, the
NBM even calls for up to 50% chances of sub-freezing temperatures
for Tuesday morning, though the LREF chances are significantly
lower. By the end of the week, NBM highs are widespread 70+. The CPC
6-10 and 8-14 day outlooks both show 50+% chances for the UP to be
in above average temperatures for the end of September and a slight
favoring of below normal precipitation (30-40% chance).

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 752 AM EDT Sun Sep 20 2026

MVFR/IFR conditions will slowly improve to VFR by early afternoon at
IWD and CMX followed by SAW later this afternoon, but this is
low to medium confidece. Once they become VFR, though, they will
stay at that level through the remainder of the TAF period.
Other impacts throughout the TAF period include strong
northeasterly winds, which will gust up to 20 to 25 kts.

&&

.MARINE...
Issued at 312 AM EDT Sun Sep 20 2026

High pressure building to the north today in addition to gusty winds
mixing down in the wake of a Hudson Bay cold front looks to bring 20-
30 kt northeast gusts to most of Lake Superior. Waves across Lake
Superior (especially in the south and the west) build to 4-6 ft.
Waves increase to near 3 feet over northern Lake Michigan and Green
Bay by Monday as well due to prolonged easterly flow approaching 20
kt. For the beginning of next week, high pressure building over
Northern Ontario opposing low pressure over the Lower Mississippi
Valley will drive some gradient wind gusts to around 20 kt out of
the east before model spread and forecast uncertainty increases late
in the week.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement through this evening for MIZ005-006.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

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