004
FXUS63 KAPX 021047
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
647 AM EDT Tue Sep 2 2025

.KEY MESSAGES...

- Isolated showers and storms today.

- Rainy and colder Wednesday

- Cold and unsettled weather continues through the weekend

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 318 AM EDT Tue Sep 2 2025

PATTERN SYNOPSIS/FORECAST:

Ridging still hanging out over the western US...with general/broad
troughing over the eastern US (subtle PVs in the Midwest and a more
notable one over NY)...and a bit of PV embedded over the central
CONUS/Mid MS Valley between the ridge and trough. Weak flow over
much of the CONUS, and a few col regions noted, particularly over
western Canada/Pacific Northwest and in the Midwest. Stronger and
much more progressive flow across central and northern
Canada...where sharp baroclinic zone and attendant surface cold
front hangs out between warm air to the south...and dramatically
colder air to the north (0C line at 850mb creeping down into Hudson
Bay and Ontario). Some deeper moisture with this, though better
moisture stretches down through the central Plains into the Gulf,
which is currently not open for business for our purposes.

As upstream system begins to sharpen up across the Canadian Prairies
today/tonight...expecting flow to start moving again across our
region...with a little bit more westward motion in the upper levels
than the last couple days...though surface high pressure holds on
here for one more day, with a shot at some afternoon popcorn
showers/(storms?). PV maxima to track southeastward across the
Canadian Prairies today/tonight...approaching our region by early
Wednesday morning...bringing our next shot at appreciable,
widespread rainfall.

Primary Forecast Concerns through Tonight:

Rain/storms this afternoon...Atmosphere continues to look more
supportive of convection today vs yesterday. Subtle signals for
cooling in the mid-levels this afternoon should help weaken
stability aloft and allow for better/deeper buoyancy
overall...particularly over the EUP. Think there will be a better
area of lake-breeze-related convergence over interior northern
Lower/EUP and NE Lower MI later this afternoon, particularly as flow
starts to take on more of a westerly idea than it has the last
couple days. However...some guidance soundings suggest potential for
a deep mixed layer across northern Lower (perhaps up toward 700mb),
which could keep the low-level environment overall too dry for much
convection to generate...and think this idea has at least some
merit, looking at the 0z/02 sounding (some moisture between 700-
850mb, but quickly drying before 700mb...which, if we do tap this
latter layer, will keep things much drier and quieter).
Overall...expectation will be for isolated to scattered showers and
storms this afternoon; most should stay on the tame side, though
some small hail could be possible with the most vigorous convection.
Given potential for these to be slow-moving...localized heavy rain
concerns could become an issue.

Otherwise...rain chances will be sneaking eastward toward the area
late tonight, encroaching on the Lake Michigan coast and the central
Yoop by around 9z or so...potentially with a few rumbles of thunder.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 318 AM EDT Tue Sep 2 2025

Days 2-3 (Wednesday-Thursday)...

Heavy rain concerns Wednesday; cold lows ahead...

Cold front screams in from the west Wednesday as the incoming PV
makes a beeline for the Upper Great Lakes, swinging through during
the day into the overnight...with a reinforcing shot in the evening
trying to sweep out some of the deeper moisture, which could leave
us prone to drizzle Wednesday night and perhaps Thursday? In
the meantime...guidance suggests the column will saturate quite
quickly late tonight/early Wednesday, resulting in rain (perhaps
a few rumbles of thunder) sweeping in Wednesday morning.
Abundant upper level/synoptic forcing with this feature,
combined with pwats well above an inch (closer to the high end
of climo for late September), suggests potential for another
round of better rainfall across the area. Probabilistic guidance
is again hinting at rainfall totals of around an inch, perhaps
more, especially across the EUP and Tip of the Mitt regions,
where forcing and weaker stability with the system should be
most favorable. (Hi-res probabilistic guidance suggests a decent
shot (as high as 50-60 percent) at 1-inch/6-hr rainfall rates
through Wednesday afternoon.)

Winds turn west to southwest Thursday as this initial blow of PV
quickly pivots northeastward...as a second PV screams down out of
northern Alberta/Saskatchewan going into Thursday night. This could
leave things overall quiet(ish) Thursday...though think the fall
idea with some daytime showers are possible, noting we will
definitely have overlake instability, with the 0C isotherm at 850mb
drooping near or overhead. Winds may remain light enough to allow
waterspouts to become a hazard again...though there is some
potential the cloud layer could remain too shallow for much to
evolve. Think Thursday night could be problematic for frost/freeze
concerns given this very cold regime...particularly where it is able
to stay clearer longer (most likely the Yoop, though not a
certainty). Potential saving grace could be that next system already
advecting mid and upper level moisture into the area by Thursday
night from the southwest.

Days 4-7 (Friday-Monday)...

Cold and unsettled fall weather through the weekend...

Another potent storm system looks to barrel into the Upper Midwest
Friday, driven by another shot of PV sweeping down from northern
Canada. This one could also have some interest for us, as there are
currently some signals for the system to strengthen/occlude as it
crosses our area...and could leave us open for another round of
better rainfall to wrap up the work week. Also looks like this
system will have much better wind fields aloft, and expect potential
for more wind with this system somewhere across the region. For
now...think this will be all rain attm...but can`t help but notice
how close the 5400m "stereotypical" rain/snow thickness line gets to
northern Michigan (potentially hanging out just north of Lake
Superior over Ontario into this weekend).

Think things will remain unsettled and fall-like overall across the
region with aforementioned cold air mass in place...and periodic
niblets of PV passing through longwave troughing over the eastern
US...at least, into the weekend, with some potential for ridging to
try to build into the Midwest going into early next week. This could
bring high pressure back to the area...though the downside is the
potential for frost/freeze concerns given the antecedent cold air
mass from this weekend. Not impossible we could have to deal with
this sooner rather than later, despite potential cloud cover and
breezier conditions at times later this week...but better chances
should come with high pressure (in theory, anyway).

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 647 AM EDT Tue Sep 2 2025

IFR still possible til 14Z at APN, 13Z at MBL. Otherwise VFR
thru this evening. A stray -SHRA is possible in interior
portions of northern lower MI, mainly inland of all the TAF
sites. Light winds today, with a southerly breeze picking up a
touch late tonight.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

SHORT TERM...FEF
LONG TERM...FEF
AVIATION...JZ