049
FXUS63 KAPX 170735
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
335 AM EDT Tue Jun 17 2025

.KEY MESSAGES...

- Storms possible this afternoon, including a stronger storm or two

- Heavy rain and strong storms possible Wednesday

- Wet/active and warmer for late week into the weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 333 AM EDT Tue Jun 17 2025

PATTERN SYNOPSIS/FORECAST:

Ridge axis over the Great Lakes slowly fading eastward as punch of
PV treks through the Upper MS Valley...attendant to a surface low
swirling over the nose of Lake Superior as of 4z, with an area of
convection swirling north through the tip of Minnesota into
Ontario/Lake Superior; a bit of convection holds on across central
WI. Southern stream ridge axis centered over the GA coast...with
excellent return flow into the OH Valley as troughing maintains its
hold on the length of the MS Valley. A baroclinic zone remains
stretched through the OH Valley...holding the better moisture off to
our south attm. Progressive west-southwest flow across the western
US, with several niblets of energy trekking through the flow,
including one into NV and another into Saskatchewan. Elevated mixed
layer continues to spread eastward into the central Plains/MS Valley
as a result. Here in the Upper Great Lakes...dry air still tries to
cling to the area in the low-levels, especially across NE Lower,
though moisture aloft is on the increase...and mid/high clouds are
starting to deepen over the area, with potentially even a few
showers crossing northern Lake MI as of midnight.

Surface low to deepen as it crosses northeastward into
Ontario...ultimately dragging a cold front into the region today. A
little timing uncertainty with this still...but expectation is for
it to cross around midday or so, before stalling out across
central/southern Lower tonight. Another PV rides up this boundary
into the region Wednesday, deepening another surface low across the
Lower Great Lakes Wednesday night. This will bring a threat for
additional convection to the region Wednesday, including a threat
for heavy rain up in our neck of the woods. Brief northerly flow
Wednesday night into early Thursday to cool things down one last
time...before the ridge axis begins to build across the eastern US
for late week. Think this will bring another threat for convection
at times late this week...with temperatures likely turning much
warmer into early next week as strong ridge axis sets up over the
Eastern Seaboard. Southwesterly flow across the central US supports
potential for additional activity through the remainder of the
period.

Primary Forecast Concerns through Tonight:

Thunder Threat Today...Think we could see a few showers/storms this
morning ahead of a narrow theta-e axis progged to cross the area
through 15-18z. Best timeframe for more noteworthy storm development
looks to be largely around or after 18z through 21z, though could
start as early as 15z across NW Lower...and hang on across Saginaw
Bay through 0z. Threat will be greatest across northeast Lower
Michigan, as it will have the best chance to achieve warmer temps to
aid instability ahead of the cold front. One concern is the amount
of dry air still present across NE Lower, which could keep some (or
much) of the rain from reaching the ground, in addition to limiting
instability potential. This being said...dry air could have
potential to accelerate downward motion and boost the threat for
gusty winds with storms. Wind fields aloft are not terribly exciting
(generally 30-40kts in the mid-levels), but enough bulk shear could
be present to allow for a stronger storm or two.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 333 AM EDT Tue Jun 17 2025

Potential for strong storms Wednesday...Still a bit of uncertainty
in exactly where the boundary stalls out tonight, and where surface
low pressure will spin up. Positions of both of these will be
relevant to threat of additional low-level directional shear to add
more spin to the atmosphere with a much more dynamic environment
present as wind fields aloft further increase (500mb winds
approaching or exceeding 50kts near the PV max that will drive the
surface low). Not impossible the front lifts back northward toward
the US-10/M-55 corridor, or perhaps further north, which would
increase our severe threats and add the threat of tornadoes into the
mix...though for now, signals seem to point toward the boundary
remaining further south across central/southern Lower MI.

Heavy rain threat Wednesday...potentially more pressing concern for
our area is heavy rain, particularly if we remain north of the front
and northeast of the surface low. With pwats increasing to or above
1.5inches Wednesday across the area...in the presence of better jet-
level forcing and mid level deformation axis...suspect a more
widespread heavy rain threat will be in play for some portion of the
area. Certainly possible this area of forcing sticks around for much
of the day, perhaps into Wednesday night, which could further
enhance the threat for an area of heavy rainfall...though if the
system ends up being more progressive, totals would be limited. Do
have some concerns about the antecedent dry air mass limiting
totals, too...but think that eventually, the unusually high amount
of moisture moving in should be able to overcome it...at least, to
some degree. Probabilistic guidance attm suggesting moderate-high
confidence in at least an inch of rainfall in 24-hrs; 2-3 inches by
Thursday morning may not be out of the question
either...particularly if/where activity gets better focused.

Additional storm/heavy rain potential late week...broad ridge axis
still expected to build to our west across the Plains/International
Border as we close out the workweek. Setup favors strengthening
low/mid-level flow which should a) advect elevated mixed layers
further northeast into the MS Valley/Midwest compared to the current
event... and b) feed Gulf moisture orthogonally into a boundary...
both of which suggest a threat for better convection/heavy rain
potential across the Upper Midwest into the Great Lakes late this
week.

Heat this weekend/early next week...Ridge axis ultimately looks to
build eastward, moving nearly overhead by the end of the weekend
into early next week...setting up the potential for our first real
hot weather of the summer...with potential for highs to touch the 90
degree mark, pending clouds/precip.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 124 AM EDT Tue Jun 17 2025

A few showers will transit the area overnight, perhaps
impacting CIU. Better precip chances arrive Tuesday, ahead of a
cold front. Showers and a few TSRA are expected. Some MVFR cigs
are expected to be associated with this activity, mainly at
CIU/PLN this afternoon. Brief vsbys restrictions are possible
with heavier showers.

Breezy sw winds develop Tuesday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 9 AM this morning to 5 PM EDT this
     afternoon for LHZ345.
     Small Craft Advisory from 9 AM this morning to 5 PM EDT this
     afternoon for LMZ323-341-342-344>346.

&&

$$

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