732
FXUS63 KAPX 070721
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
321 AM EDT Sun Jul 7 2024

.KEY MESSAGES...

- Mainly quiet weather today with rain chances, rumbles of
  thunder returning tonight.

- Rain/storms Monday and Monday night/Tuesday.

- Potential for Beryl`s Remnants to Impact Northern Michigan
  Wednesday and Beyond.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 316 AM EDT Sun Jul 7 2024

Pattern Synopsis:

Short wave ridging will continue to slide over the Great Lakes this
morning into this afternoon, providing subsidence aloft that will
slowly build surface high pressure east of the region through the
period. Meanwhile, longwave troughing will progress from the Great
Plains over the Midwest by Monday morning, generating enough forcing
aloft to create a weak, broad surface pressure response across the
region.

Forecast Details:

Mainly quiet today, rain chances/thunder tonight -- With high
pressure in place across the Great Lakes, mainly quiet weather is
expected through this evening. Morning fog should dissipate shortly
after sunrise as diurnal heating/mixing ensues. While a few showers
cannot be entirely ruled out during daylight hours, subsidence aloft
and relatively dry low-level profiles lead to very low chances (10%
or less) at this time. The main chances for rain and the potential
for a few rumbles of thunder will return late this evening and
tonight as aforementioned troughing/surface pressure falls work into
the Great Lakes. Severe storms are not expected with weak buoyancy
and shear in place. Otherwise, temperatures look to warm into the
low 80s for most areas this afternoon with mild overnight
temperatures in the low to mid 60s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 316 AM EDT Sun Jul 7 2024

PATTERN SYNOPSIS/FORECAST:

Longwave troughing continues to overtake the central
continent...with rather nebulous flow/generalized high pressure
overall hanging over the northern US/southern Canadian Prairies,
including northern Michigan. Even so, a handful of pv niblets in the
flow, including a well-defined swirl over SD/MN with attendant
convection ahead of this...and a surface cold front stretching back
into WY. Additional niblet over the central Plains with better theta-
e advection and 20+kt LLJ with its own surface reflection over
Nebraska/KS. Otherwise...primary BCZ over the nation stretches from
New England down to southern TX with a 100+kt upper jet stretching
up into the eastern CONUS; bulk of the deep moisture (pwats greater
than 2in) along and south of this from the Gulf Coast up into the
Mid Atlantic. BCZ extends back northwestward into the Canadian
Rockies, with additional niblets being funneled into the NW US along
that portion of the flow ahead of anomalous ridging over the West
Coast. Otherwise...eyes remain on T.C. "Beryl" in the western
Caribbean as it eyes the TX coast.

This same general pattern to remain largely the idea going into the
start of the workweek...as upstream troughing looks to firm up over
the central Plains as Beryl makes landfall Monday morning. General
idea attm is that our upstream troughing will ultimately scoop up
Beryl and allow it to hitch a ride northeastward into the OH Valley
for midweek. While the general idea keeps it over southern Michigan
and the OH Valley...will be something to keep an eye on going
forward given some uncertainty in that portion of the forecast attm.
In the meantime...will look for a wad of PV and moisture to slip
northeastward over the Upper Midwest Monday, which should drive some
shower/tstorm activity in our general region going into Monday
night. Potential break in the action Tuesday before Beryl`s remnants
begin to track up the BCZ into the OH Valley going into midweek.
Additional energy dives into the back of troughing over the Upper
Midwest Wednesday...which looks to keep the troughy idea in place
over the region through much of the upcoming week. Meanwhile,
upstream pattern should begin to break down, with ridging looking to
spread eastward over the central continent going into the latter
half of the week, driven by a system crossing central Canada. A lot
of questions yet with the end of the forecast for the upcoming
weekend, given the potential for troughing to hold over the Great
Lakes...as well as our proximity to the eastward-expanding heat
dome. While nothing is certain by any means, suspect things should
remain generally unsettled (perhaps more than is currently in the
forecast) over some portion of the Midwest right on into next
weekend. Stay tuned.

Primary Forecast Concerns:

Rain/storms Monday and Monday night... Expecting an initial round of
elevated, warm advection convection to slip through during the
morning hours Monday. Some uncertainty in the timing/position of
this, though, with potential for the primary bout of rain to stay
further north across the Yoop...or further south, more or less
focusing over central Lower and West Michigan. Either solution is
possible from the pessimistic viewpoint that convection tends to
split around northern Michigan (and Gaylord in particular)...though
in this case, not so sure it will be a split as much as dependent on
timing...and could honestly see it going either way:  a quicker
solution would have a tendency to trend more south and east
(particularly if convection is at all organized and the right-
leaning Coriolis force comes into play, though signals for well-
organized convection are not strong attm), while a solution that
slows the wave would more likely focus rain/storms across the
eastern/central Yoop, perhaps as far south as NW Lower into the Tip
of the Mitt region. Given the wildcard of Beryl...do have to wonder
if the slower solution will ultimately win out...but for now will
lean a little more toward the quicker/more southern solution.

Think we`ll be looking at potential for redevelopment in the
afternoon with increased diurnal heating and continued slow movement
of a weak SW-NE oriented BCZ ahead of the trough aloft. Deep layer
shear attm appears a little better, perhaps approaching 20-
30kts...but think that low-level wind fields will be weak
enough to support lake breeze development (particularly along
the Lake Huron coast), which could further focus mesoscale
convergence over NE Lower. The slightly better deep layer shear
suggests convection may try to get a little more beefy/better
organized, which could be problematic along the lake breeze
boundary with an increased potential for turning of the low-
level winds with height (i.e., more potential for rotation) and
perhaps enough low-level instability to accelerate upward
motion/boost stretching of vorticity. For now, though, think any
tornadic threat is on the lower side...but will be something to
keep an eye on, particularly given that the last couple
tornadic events up here haven`t necessarily been classically
impressive. Otherwise, do think gusty winds could be a threat
again with some potential for low-level dry air that could
enhance evaporative cooling/downbursts with convection, despite
winds aloft not being terribly impressive as far as exact severe
thunderstorm (50kts/58mph) wind criteria goes. Hail threat may
not be overly impressive with a lack of sub-freezing cloud
depth...but certainly even small/sub-severe hail could help the
cause of downbursts.

Other threat with the activity Monday is heavy rain, with warm rain
processes remaining in play amid increasingly anomalous moisture
over the area. While slightly better wind fields aloft could
certainly lead to slightly quicker storm motions than we`ve seen the
last couple days or so...do think it`s not out of the question some
areas could see training/backbuilding storms along mesoscale
boundaries (e.g., the Lake Huron lake breeze)...which could produce
a localized significant amount of rainfall in a short period of
time. Probabilistic guidance suggests that 24-hr rainfall totals by
8am Tuesday could be an inch or greater on the worst case scenario
end of things. Think the broader focus for these heavier rainfall
totals will be NE Lower Monday into Monday night...and think
activity should hang on into at least part of Monday night, with the
boundary likely a bit slower to move through over there. If the
boundary ends up hanging out over NE Lower...think another round of
pop-up showers/storms could be in the works for Tuesday.

Potential for Beryl`s Remnants to Impact Northern Michigan?... This
may be the trickiest part of the forecast attm...given uncertainty as
it gets scooped up by our northern stream troughing early this week.
There are decent signals for additional northern stream energy to
dive into the back of the trough Wednesday...which could buckle
things further northwest than currently anticipated (at worst case
scenario). Do think there could be a tight gradient on the north
side of this system...with high pressure potentially settling in to
our north...which bears watching as well, as it could help drive the
northern edge of the precip shield further south. Even so...with
tropical moisture and well-organized surface system crossing the
Ohio Valley...think at least some portion of our area (even our more
vulnerable hydrological areas toward Saginaw Bay) could be in a
favorable position for a prolonged period of steady/heavy rain.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1008 PM EDT Sat Jul 6 2024

Still anticipating the formation of MVFR to IFR producing
fog/mist and stratus early this morning, especially targeting
KCIU and KMBL. Expect fog/mist and stratus to rapidly burn off
after sunrise, leaving behind VFR conditions under some
scattered high clouds and relatively high based cumulus. Light
winds with local lake breeze development this afternoon.

&&

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

&&

$$

SHORT TERM...DJC
LONG TERM...FEF
AVIATION...MSB