353
FXUS63 KAPX 021807
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
207 PM EDT Tue Sep 2 2025

.KEY MESSAGES...

- Isolated shower/storm this afternoon.

- Increasing rain chances and turning cooler Wednesday.

- Chilly and unsettled weather continues at times through the
  weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 200 PM EDT Tue Sep 2 2025

Pattern Synopsis/Forecast: Ridging evident over the Intermountain
West this afternoon with broad troughing over the eastern half of
the CONUS. At the surface, ~1019mb sfc high pressure overhead will
gradually trek east toward the eastern seaboard tonight. Focus
quickly turns to Wednesday with anomalously strong closed upper-
level low pressure barreling southeast out of Canada, along with
associated sharp low-level baroclinic zone that will become the
focus for surface low development over the western Great Lakes. As a
result, increasing chances for showers, maybe a few rumbles of
thunder, and a return to much cooler weather is on tap.

Forecast Details: Still low chances for an isolated shower/storm
this afternoon along inland penetrating lake breezes. Already
seeing this across parts of Emmet into western Cheboygan County
as of 2 PM. That said, still think that vast majority of the
forecast area remains dry.

Moisture steadily increases late tonight into Wednesday morning in
advance of approaching cold front set to trek across northern
Michigan during the day. PWs progged at or above 1.25" combined with
abundant forcing should yield pretty widespread/beneficial rain for
much of the forecast area. Hi-res probabilistic guidance still on
the order of 50-60% chance of rain amounts exceeding an inch by 00z
Thursday across parts of northwest lower and the eastern U.P.
Similar probabilities for an inch or more across north-east lower by
12z Thursday. Suppose an embedded rumble of thunder can`t be ruled
out with this activity given fumes of instability, but no severe
weather is anticipated, despite increasingly favorable deep layer
shear. Aside from wet weather, will be a notable return to
cooler/fall-like temperatures that really becomes evident Wednesday
night and beyond.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 200 PM EDT Tue Sep 2 2025

Pattern Forecast: By Wednesday evening, sfc low pressure expected to
be situated near the south end of James Bay with associated cold
front now largely off to our east. Strong cold advection in that
boundary`s wake through Wednesday night with continued chilly/fall-
like air remaining in place through the upcoming weekend. Additional
periods of wet weather expected through the long term forecast
period, as well, with a favorable over-water thermal gradient
yielding lake effect processes ramping up, lingering wrap around
moisture tied to slowly departing low pressure, and an occasional
mid-level wave(s) rounding the base of parent troughing overhead
(most notably Friday).

Forecast Details: Wednesday night, strong cold advection continues
and while the bulk of deep layer moisture is expected to be exiting,
suppose we could see some lingering drizzle/light showers at times.
Low temps Wednesday night largely in the low-mid 40s with a
prevailing northwest wind. Winds Thursday turn southwesterly, breezy
at times. While there`s not a lot of deep moisture to work with, a
favorable over-water thermal gradient yields plenty of over-lake
instability, which should lead to at least some scattered lake
induced rain showers across parts of forecast area -- most
numerously in the typical southwest lake belts of northwest lower
stretching into Mackinac County. Highs Thursday largely in the 50s
(some lower 60s near Saginaw Bay) only to be made a few degrees
cooler given breezy winds.

By late Thursday night/Friday, another mid-level wave is expected to
be trekking through larger scale troughing aiding to produce another
round of more numerous showers. Cool, showery and occasionally
breezy conditions progged to continue at times through the remainder
of the weekend -- with most numerous in the lake belts.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 138 PM EDT Tue Sep 2 2025

Cloud cover will breifly dissipate this evening then begin to build
overnight tonight. KAPN will continue gusty easterly winds
from Thunder Bay this evening until diminishing around 03Z tonight.
Cigs will lower Wednesday to MVFR and IFR along with developing
shower and scattered storm chances. Gusty southwest winds will
develop around midday Wednesday eventually turning northwest
just beyond the end of the forecast period.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 8 AM to 11 PM EDT Wednesday for
     LHZ345>349.
     Small Craft Advisory from 2 AM to 11 PM EDT Wednesday for
     LMZ323-341-342-344>346.

&&

$$

SHORT TERM...MJG
LONG TERM...MJG
AVIATION...SJC