178
FXUS63 KAPX 161029
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
629 AM EDT Wed Jul 16 2025

.KEY MESSAGES...

-Hot and humid today with scattered showers and thunderstorms,
 particularly across northern lower Michigan. Potential for
 torrential rainfall and gusty winds with these storms.

-Another round of showers and thunderstorms passes through the
 area, particularly in areas along and south of M-72. Potential
 for torrential rainfall, gusty winds, and a non-zero tornado
 risk.

-Drying out and turning quite cooler Thursday. Highs likely
 range from 65 to 75 degrees.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 304 AM EDT Wed Jul 16 2025

Current Overview / Pattern Synopsis:

Departing area of surface high pressure will ease its influence
across northern Michigan as the next 24 to 30 hours trend more
active. Stationary frontal boundary currently stretching from Val
-d`Or, Quebec to North Platte, Nebraska. Zonal flow regime aligns
well with the front, with a series of waves riding the boundary...
all convectively charged... one over northeast Ontario, another
associated with repeated rounds of storms across the Wisconsin
Highlands and western upper Michigan, and another developing across
South Dakota and Nebraska. Strong area of surface high pressure in
Canada will move south and east with time, forcing the frontal
boundary south and east toward northern Michigan. Subtle diffuse
moisture boundary / wind shift draped across eastern Wisconsin,
turning southeast toward Muncie, Indiana and Columbus, Ohio.

This boundary will be drawn northward as large scale ascent
increases, leading to a surge in moisture content across the region.
Minimal forcing will lead to a disorganized convective mode in the
afternoon, consisting of pulse dominant convection in a moist (1.5+
PWATs) profile. Then, as the front works closer, an upstream wave
originating from the aforementioned South Dakota / Nebraska
convective complex works closer, bringing potential for a linear
convective mode to scrape parts of northern Michigan, aided by LLJ
acceleration (25 to 40 kts), moisture intrusion (PWATs swell as high
as 2.0 after 00z), and just enough lingering surface instability to
keep the potential for storm maintenance from coast to coast across
portions of lower Michigan, possibly impacting the southern few rows
of counties of the APX CWA.

Forecast Details:

There will be two distinct convective episodes across the region. As
far as outlooks go for today... northern Michigan (especially
northern lower) is squarely within a Marginal Risk for Excessive
Rainfall (via WPC) today, with a Slight Risk poking into the
southern CWA. Much of northern lower is in a Marginal Risk for
Severe Storms (via SPC), with a Slight Risk poking into Manistee
County.

Scattered showers and storms later this morning into the afternoon:
Starting off largely dry, with the best chances for a shower by
daybreak favoring eastern upper along the immediate surface
frontal boundary. Rapid destabilization anticipated as deeper
moisture surges into the region, leading to widespread surface
dewpoints in the upper 60s to near 70 across northern lower.
Surface temps quickly rise well into the 70s and into the 80s,
with the most aggressive CAMs initiating convection across the
SW CWA as early as 14z. Expecting scattered showers and storms
to continue blossoming across the region through the afternoon
with a pulse dominant mode. With the aforementioned surge in
PWATs coupled with weak upper flow and bulk shear of 15 to 20kts
through the afternoon, anticipating slow-moving, torrential rain
producing storms to be the rule this afternoon, especially
along/south of a Beulah to Rogers City line. Primary hazards
with this activity will be localized rainfalls in excess of
2.50" in a short time, which may lead to marginal flooding
concerns... along with some gustier winds from any updraft
collapses into the afternoon. Radar presentation will likely be
littered with thunderstorm outflow boundaries by the afternoon
as storms pulse up and down.

Potential for a line of storms tonight: Latest CAMs continue to lay
down the potential for a convectively charged wave to progress
eastward from NE/SD through Iowa and into Wisconsin by this
afternoon. Strength of this wave remains in question due to
convective contamination in guidance, but nonetheless, it sure looks
like shower and storm development should materialize across central
into eastern Wisconsin through the afternoon, congealing into a
linear segment (and potentially) a larger bow echo that looks to
cross Lake Michigan early this evening, moving into lower Michigan
with time as we move into the overnight. Waning instability should,
from a conceptual standpoint, lead to a lessening intensity of this
feature as it progresses eastward through lower Michigan. That being
said, reinforcing LLJ acceleration to as high as 40kts on the most
aggressive of CAMs suggest that convective maintenance is possible
at the nose of this increasing LLJ field due to the presence of some
elevated instability. General theme is that this convective complex
should pass somewhere along and south of M-72, with only increasing
potential the farther south one goes. It is possible that the
greatest risk for this complex of storms to pass holds just south of
the area, but where this feature occurs will likely only show its
cards until later in the afternoon.

As far as hazards with this particular feature goes, torrential
rainfall, possibly aided by some echo training due to slow
advancement of this feature, is on the table with PWATs as high as
2.0, and a classic warm rain profile. In the event this overlaps
some spots that get downpours this afternoon, another flooding risk
may arise as this setup can yield impressive rain totals of 2.00"+
with ease. In addition, anticipating that there will be potential
for some damaging winds with this feature, especially if a bookend
vortex on the north end of the line can get into the CWA.
Furthermore, with low LCLs in the moist atmosphere and shear
ballooning to 40 to 45kts, suppose there is an embedded tornado
threat as well if enough surface instability can be realized. In the
event this particular feature holds south of the CWA, this will
dramatically decrease potential for severe weather across the region.

So after all that... what else is in store across the region? North
of this possible complex of storms, efficient stratiform rains are
on the table, with potential for an additional 0.50"+ of rain,
generally south of M-32. From M-32 to the Bridge, it is entirely
possible that you land in "meteorological purgatory", an atmospheric
state characterized by perhaps some lighter passing showers and
plenty of dry time. This particular region will see the lowest
overall chances for rain tonight. North of the bridge, mid level
frontogenesis may lead to a band of stratiform rain that looks to
bisect eastern upper from SW to NE. Most spots in the eastern Yoop
probably see 0.25" or less outside of this main fronto-driven band,
but areas that land under this more efficient rain band could see
over 1.00" by daybreak Thursday.

Later tonight: Once the wave and associated frontal boundary clears
the area to the south and east later tonight, expecting shower and
thunder chances to decrease from NW to SE into Thursday morning,
with just some lingering showers gradually becoming confined to
northeast lower with time through Thursday morning, with dry and
sunnier conditions largely prevailing into the afternoon. Will have
to watch Canadian wildfire smoke trends in the wake of this passage,
but latest guidance is pessimistic toward higher concentrations of
smoke over the region, so thus perhaps the occasional haze is
possible through the day. A sharply cooler airmass will be in place
Thursday... and boy howdy is it sharp. Average highs this time of
year are generally in the upper 70s to lower 80s. Anticipating
daytime highs across the region to peak anywhere from 65 to 75...
warmest in Gladwin, Arenac and Iosco counties.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 304 AM EDT Wed Jul 16 2025

Strong area of Canadian high pressure set to build through the
weekend, bringing with it quite the drop in humidity with slightly
below normal daytime highs into the weekend. As such, this will
likely allow those looking to give their air conditioners a break to
do so. With Thursday`s afternoon highs being so low, anticipating
quite the chill across the area Thursday night as winds decouple and
temperatures plummet into the 40s and 50s. Dry Friday with highs in
the low to upper 70s, overnight lows in the upper 40s into the 50s.
Another wave passes through this weekend, returning rain chances for
Saturday. High pressure returns into Sunday, with seasonable
temperatures in the 70s and 80s. Looking ahead to next week, return
flow looks to build in, which should draw in warmer and a little bit
more moist air to the region. Thus, expecting highs to peak back
into the low to upper 80s at times, with occasional shower and storm
chances not off the table, especially heading toward midweek.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 622 AM EDT Wed Jul 16 2025

Scattered showers and storms are expected to develop across the
area today, becoming more numerous this evening. While mainly
VFR conditions are expected today as cloud bases remain fairly
elevated, any storms that manage to impact a taf location will
be capable of producing brief gusty winds and vis restricting
heavy rain. Band of MVFR to IFR cigs expected to spread from
northwest to southeast across the region tonight, with the
threat for additional showers continuing.

&&

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

&&

$$

SHORT TERM...HAD
LONG TERM...HAD
AVIATION...MSB