787
FXUS63 KAPX 211045
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
645 AM EDT Sat Sep 21 2024

.KEY MESSAGES...

- Some dense fog this morning

- Rain/storms return very late tonight into Sunday night

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 341 AM EDT Sat Sep 21 2024

Pattern/synopsis: A slow-moving cold front bisects northern MI
from nw to se. Precip has m moved off to the east, associated
with a mid-level trof and better moisture/instability. Drier
mid-level air has ended precip, but contributed to fog. The
front progresses eastward out of the area this morning, and high
pressure will poke northward into lower MI by midday.

Forecast: Fog is the most immediate concern. Fog has been dense
in spots. Satellite imagery suggests the most substantial fog in
in the tip of the mitt counties, and in the far se. Was thinking
a couple hours that a fog advisory was likely...but for now, the
number of surface ob sites indicating dense fog is limited. (At
this moment: PLN/MGN/MBL/Y31). That`s fewer than two hours ago
(for example, CAD-HTL have improved). Would think things would
still tend to worsen thru sunrise (though the pressure gradient
is a touch tighter in nw lower MI vs southern lower). For now,
just have an SPS out mentioning fog. Will continue to monitor
satellite and surface ob trends.

Satellite does hint at much of our fog/stratus being on the
shallow side. The exception is in parts of eastern upper MI
(including just w of our area at ISQ-ERY). Expect fog/low clouds
to mix out somewhat faster in the south than in the north.
Places south of M-32 should be comfortably mostly sunny by
midday, but it may take thru early or even mid afternoon to the
north. Building 500mb shortwave ridging will sharply limit Cape,
and diurnal convection is not expected here.

Max temps mid 70s north to mid 80s far se.

Tonight, the upper ridge gets shunted east across Lk Huron, with
weak energy lifting ene-ward into the central lakes. A quick
shot of return flow gets going tonight, in advance of another
cold front approaching western sections by Sunday morning.
Warm/moist advection in low levels, and some troffing aloft,
will contribute to marginal destabilization. This instability will
be very marginal here (MuCape values struggling to reach triple
digits), but more substantial just w of Lake MI (where MuCape
values reach high triple-digits. Deep convection should initiate
later today in the far upper MS Valley. Stronger/more organized
convection should tend to turn se-ward with time tonight, as
storms search for better instability/inflow. But some
pre-frontal convection will fight its way into the region
tonight, eventually overcoming the drier air initially in place.
There could be a stray shower in the far west by midnight, but
better pops arrive later. By late overnight, chancy pops are
found nw of a line from CAD to Onaway, including the eastern
UP. The highest pops will be in western Chip/Mack Cos. A rumble
of thunder is possible, but severe wx is not expected, given the
lack of significant instability.

Min temps mid 50s to near 60f.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 341 AM EDT Sat Sep 21 2024

Pattern Synopsis and Forecast:

Midlevel split flow over the CONUS will continue chances of active
weather to the Great Lakes region for the first part of the long
term. Current above average temperatures influenced by southern
branch flow will eventually advect southward. A more active
northern branch will allow for cooling temperatures next week.

The first shortwave trough currently over the Canadian/Montana
boarder will make its way to the Great Lakes region at the start of
the Long Term. No impactful weather is expected at this time, but
showers and storms could persist across the CWA (at times) through
the first half of the forecast period. Upstream ridging eventually
returns surface high pressure and sunny skies during the second half
of next week around the Wednesday timeframe, but northern branch
flow will keep Fall-like temperatures for the entire week.

Primary Forecast Concerns/Key Messages:

Cooler temperatures move into the Great Lakes region next week:
No high impactful weather to discuss during the long term.
Biggest story will be the end of warmer than average
temperatures as northern branch flow advects southward this
Monday. Current daytime highs in the 80s will lower into the
upper 60s to low 70s for most areas next week, finally returning
temperatures somewhat closer to normal.

Showers and storms return this Sunday: Aformentioned troughing
will move in this Sunday while developing a weak surface cold
front at the same time. While most areas can expect minor QPF
amounts (roughly a half inch or so) localized areas that undergo
more efficient convection could see locally higher amounts as
PWATs climb to well above normal and a warm, deep cloud layer
could result in locally higher totals. Additional small showers
could continue into Tuesday as strong flow aloft moves through
the Ohio Valley, but substantial QPF is not expected at this
time.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 645 AM EDT Sat Sep 21 2024

Widely varying conditions early this morning, though improvement
is expected across the board after sunrise. Fog/stratus
impacting most sites to a greater or lesser degree (except for
TVC). Conditions will be slower to improve up at CIU, fast at
APN, with PLN/MBL in between. But all sites should be VFR by
early afternoon. Then we stay VFR tonight, with increasing mid-
high clouds transitioning to some -SHRA as we head into the day
Sunday.

Light winds.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EDT this morning for MIZ025>029-
     031>036-041-042.
MARINE...None.

&&

$$

SHORT TERM...JZ
LONG TERM...SJC
AVIATION...JZ