052
FXUS63 KMQT 051801
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
201 PM EDT Fri Sep 5 2025

.KEY MESSAGES...

- Lake effect rain showers persist today for the NW to W wind
  "snow" belts.

- Blustery NW to W winds increase this afternoon. There is
  currently a 40 to 90% chance for gusts >30 mph, with the
  highest probability in the Keweenaw and W to NW exposed
  shorelines of Lake Superior.

- Gale Warnings have been issued for strong south to southwest
  winds on northern Lake Michigan and northern Green Bay this
  morning and across all but far western Lake Superior for
  strong west winds today.

- A cool airmass will remain over the Upper Great Lakes through
  the weekend, with some moderation expected early next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 351 AM EDT Fri Sep 5 2025

Early morning GOES satellite and RAP analysis reveal deep troughing
across the entire northern tier of the CONUS with a handful of
embedded shortwaves embedded within the longwave feature. At the
base of this trough extends an impressive 130kt jet streak from SD
now nosing into the Straits of Mackinac at the time of writing this
discussion. Strong synoptic lift underneath the left exit region of
this upper jet is supporting a ~994mb sfc low pressure in far
northeastern WI which continues a slight NNE trek through the UP
this morning. Aloft, stout low to mid level WAA and frontogenetic
response has forced a band of light to moderate rain that continues
to press NE this morning. Noted on WV imagery is the system`s dry
slot nosing into the S-central UP counties and shutting off
precipitation. However, so far areas of the west and central UP have
already managed to pick up a quarter to a half inch of rain. One
cant help but think this would have been an impressive quick hitting
band of snow should column temperatures have been cold enough, but
we will get there in the coming months.

Heading into the rest of the day, the shortwave aloft and sfc low
continue east through the UP before lifting NE towards James Bay
this afternoon. As this occurs, increased W to NW flow will support
CAA aloft characterized by 850mb temps falling between 0 to -3C this
afternoon. With average Lake Superior sfc temperature around 16.5C,
lake sfc to 850 delta Ts will be sufficient enough for lake effect
rain showers this afternoon across the NW to W wind "snow" belts.
Additionally, coupled with strong pressure rises (5-8 mb/6hrs
immediately behind the departing sfc low), model soundings indicate
efficient mixing into a 35-40kt LLJ which should result in an uptick
in strong wind gusts 30-40 mph through the afternoon, especially in
the Keweenaw. 00z HREF guidance suggests a 50-80% chance for gusts
>30 mph across much of the west half with pockets of >90% in the
Keweenaw and western Lake Superior shorelines. For more details
regarding winds and waves on Lake Superior, see the Marine
Discussion section below.

Otherwise, temperatures in the west and interior central UP may only
peak near 50 this afternoon, while the s-central and east manage to
climb into the low to mid 50s. Tonight, winds are expected to let up
some behind the departing system, though CAA overhead the relatively
warm lake will keep elevated winds 20-25 kts over the lake and W to
NW exposed shorelines. Lake effect rain showers persist over the
same areas through much of Saturday as chilly NW flow continues into
the weekend, though a punch of drier air aloft may limit lake effect
rain showers during the afternoon ahead of another incoming
shortwave.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 447 PM EDT Thu Sep 4 2025

Combination of short-wave energy and lake-effect in favored west to
northwest trajectory areas will continue through Sunday, but high pressure
will bring a break in the rain Sunday night into Monday. The highlight
of this period will be increased potential for frost for interior locations
late Sunday night, as temperatures drop into the middle 30s.

WAA ahead of an approaching cold front will bring showers and
a few thunderstorms to the region late Monday night into Tuesday, with
continued rain chances as the cold front moves through Tuesday night into
Wednesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 155 PM EDT Fri Sep 5 2025

Scattered lake effect rain showers persist across the UP this
afternoon within a chilly NW flow regime, producing a mix of
VFR and MVFR conditions along with 25-30 kt wind gusts at area
terminals. Expect showers to taper off and winds to gradually
diminish 02-08z tonight as an embedded mid level disturbance
rotating around the northern Ontario low departs to the east,
yielding improving VFR cigs. VFR then prevails through the
remainder of the TAF period, with winds continuing to gust to
around 25 kt at KCMX.

&&

.MARINE...
Issued at 447 PM EDT Thu Sep 4 2025

The main focus will be potential for gales late tonight into
Friday as a strong clipper-type low pressure system moves through
northern WI and the eastern Upper Peninsula.

Strong south to southwest winds develop ahead of the low over Green Bay
and northern Lake Michigan late tonight into Friday morning. Strong west
winds develop elsewhere as the low departs and CAA develops on Friday.
Probabilistic data has been keying in on the Gale potential for Green Bay,
northern Lake Michigan and eastern Lake Superior, but think that gusts
to around 35 knots are likely over most of the Lake Superior on Friday
in the strong gradient and CAA regime. Have converted Gale Watches over
Lake Superior into warnings for the Friday into Friday evening
period.

The pressure gradient will begin to weaken Friday night, with most
of the lake falling below 20 kts by Saturday morning (the exception
being near the Keweenaw where gusts to 25 kts will hold on through
the day). For Saturday night through early next week, expecting the
winds to be lighter, below 20 knots.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement until 11 PM EDT this evening for
     MIZ005-006.

Lake Superior...
  Gale Warning until 11 PM EDT /10 PM CDT/ this evening for
     LSZ162-240>251-263>267.

Lake Michigan...
None.

&&

$$

SHORT TERM...BW
LONG TERM...NL
AVIATION...CB
MARINE...NL/TAP