785
FXUS63 KAPX 051034
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
634 AM EDT Sat Jul 5 2025

.KEY MESSAGES...

- Hot and muggy today; a few records in jeopardy

- Isolated pop-up showers possible this afternoon east of I-75, but
better chance for showers/storms with a front this evening/tonight.
Locally heavy rain possible.

- Shower/storm chances continue into Sunday, and off and on into
next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 344 AM EDT Sat Jul 5 2025

PATTERN SYNOPSIS/FORECAST:

Southwesterly flow across the central US...with shortwave in the
flow stretching from upper low over the PacNW...into the central
Plains. Ridge axis stretches from TX northeastward into the Upper
Midwest. Northern stream energy crossing central Canada taking the
peak off the ridge axis; additional trough energy stretches up the
length of the East Coast. Better tap of monsoonal moisture attm:
Pwat on the 0z/05 sounding here was 1.45in...compared to 0.33in at
0z/04...so we have moistened up, as the increasingly muggy air (and
midnight temps in the upper 60s and low-mid 70s) attests, though
there is a slight dip in deeper moisture just upstream over WI.
Surface high pressure still trying to hold on here...with flow
remaining pretty light away from the perimeter of the ridge to our
west/northwest and attendant WSW-ENE oriented cold front, stretching
from the northern Plains toward Hudson Bay.

Upstream trough axis over the Upper Midwest looks to shear out a bit
as it sinks eastward today...dragging an attendant surface trough
into the UP/WI this afternoon...and eventually into northern
Michigan tonight through Sunday. Expecting a toasty summer day
today, with highs reaching into the 90s for much of northern Lower
(heat indices approaching 100F in spots). A few records in jeopardy
today, most notably, Traverse City (old record: 96 in 2012), Alpena
(old record: 96 in 1955), and perhaps Pellston (old record: 93 in
1988), where downsloping could boost temps a bit more. (Lake breeze
development/timing could disrupt this idea at Alpena in
particular...but think SW flow will prevail.) A few showers/storms
may try to pop up today, esp over NE Lower this afternoon, with
somewhat better chances coming largely this evening into tonight,
with that front moving in from the west.

Primary Forecast Concerns through Tonight:

Shower/storm potential today...there is a shot for some activity to
try to develop across the area this morning, with potential for some
early-day diurnal heating in this air mass to develop instability,
though not sure we will have any good boundaries to kick anything
off. Better chances for pop-ups should be closer to the Sunrise Side
this afternoon, where there is a better shot of low-level
convergence to kick things off...especially if the lake breeze kicks
in, though not sure if background flow will be light enough to
support much inland motion today...and still wondering if the cap
aloft will be too strong to overcome. Some guidance suggests we may
see some kind of negative-theta-e advection from west to east this
afternoon (there are some notable hints at a plume of somewhat
aggressive drying to cross the area today, which could drop Tds into
the lower 60s rather than mid-upper 60s)...which could put a cap on
afternoon pop-ups across at least northwest Lower...though it is
less clear if this could act as a boundary for development east of I-
75.

Will be looking for the weak cold front to approach from the west
toward after 20z, approaching the I-75 corridor toward 0z, which
should kick off a somewhat better chance for showers/storms...though
think things will be more scattered in nature (i.e., not a total
washout), especially early on. Instability attm seems to largely
trail the front, which could hinder the intensity of storms;
additionally, deep-layer shear will be marginal along the boundary,
which also is not terribly favorable for better organization...but
suppose it isn`t completely impossible there could be a stronger
storm or two. Primary concern will be potential for heavy rain, as
pwats will ramp up significantly along the front...likely in excess
of 2in. If we end up drying more aggressively this afternoon, have
to wonder if this will limit QPF to some degree, especially assuming
we lack any real good focus for forcing/moisture convergence with
this front, at least in our area...and better rainfall totals will
likely remain further north in our area, closer to the Yoop, where
prob guidance hints at a 30-50 percent chance at an inch in 6hrs.
This being said...if any zonal boundaries end up cropping up (e.g.,
outflow boundaries, or a more zonal component to the front itself
across the Tip of the Mitt/Northern Lower (which is not impossible
tonight)), will need to watch that heavy rain potential much more
closely. Still wondering if we will again end up with the bulk of
the rain chances splitting around us with this event, though, as
it`s possible the better forcing/moisture convergence remains north
tonight...and better instability/moisture to our south Sunday.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 344 AM EDT Sat Jul 5 2025

Days 2-3 (Sunday-Monday)...Lingering trough axis Sunday morning to
continue to sink through the area through the day...likely exiting
the Saginaw Bay region toward mid/late afternoon...with generally
cooler temps expected, though it will be warmest across the Saginaw
Bay region ahead of the front. Still some timing uncertainty...and a
faster solution could lead to a cooler day across the whole CWA, and
keep potential activity tamped down to our south. A bit of energy
tries to slip into the Upper Midwest Sunday night into Monday,
though lack of better moisture may preclude any development...as
Canadian high pressure looks to set up over Ontario for the start of
the week. Another bit of PV trekking across southern Canada toward
our area Monday night...which could have a bit better moisture with
it.

Days 4-5 (Tuesday-Wednesday)...Surface high pressure should still be
trying to hold on, despite additional niblets of energy zipping
through the flow along the International Border. Think Tuesday`s
niblet could bring some shower chances back into the picture.
Upstream...ridge axis looks to rebuild across the Desert SW into the
western US...which suggests troughing may end up settling into the
eastern half of the US going into at least midweek.

Days 6-7 Outlook (Thursday-Friday)...Watching a potentially more
potent bit of PV to dig into western Canada mid to late week next
week...which should shift the ridge axis around a bit, perhaps into
our area going into the end of the week? Certainly not impossible we
could be looking at a period of warmer weather if the ridge axis
does end up shifting overhead ahead of PV max.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 635 AM EDT Sat Jul 5 2025

VFR thru most of today, then worsening beginning late evening.

Mainly quiet on Saturday. An incoming cold front will start to
push SHRA/TSRA eastward toward northern MI. This activity may
reach northern/western TAF sites (everyone but APN) toward/by
midnight. Have MVFR cigs/vsbys in -SHRA (and VCTS for several
hours). And by daybreak Sunday, IFR conditions progged at
CIU/PLN/MBL.

Sw winds will become breezy today, weakening somewhat tonight.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 10 AM this morning to midnight EDT
     tonight for LHZ345-346.
     Small Craft Advisory from 2 PM this afternoon to 8 PM EDT this
     evening for LHZ349.
     Small Craft Advisory from 10 AM this morning to midnight EDT
     tonight for LMZ323-341-342-344>346.

&&

$$

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