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000
FXUS63 KAPX 191045
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
645 AM EDT Mon Jul 19 2021

.NEAR TERM...(Today through Tonight)
Issued at 345 AM EDT Mon Jul 19 2021

...Increasing chances of showers and storms late tonight...

High Impact Weather Potential...Slight chance of non-severe
thunderstorms late tonight north of M-32.

Pattern Synopsis/Forecast...Strong high pressure remains centered
across the Upper Midwest and the Great Lakes region early this
morning. Strong subsidence and dry air thru the column are
maintaining mainly clear skies across this entire region...although
a thick layer of smoke at high levels via upstream Canadian
wildfires continues to result in very milky/hazy skies and filtered
sun and moon light. Temps are falling thru the 60s...on their way
down to early morning lows in the upper 50s to near 60 degrees.

As we head into today and tonight...high pressure center overhead
will slowly drift southeastward over the next 24 hours...as a weak
moisture-starved cold front drops south out of Canada and into
Northern Michigan by late tonight. Narrow band of instability right
along the front combined with weak lift and limited moisture will
provide a chance of showers and possibly a thunderstorm to Eastern
Upper and far Northern Lower Michigan after 06Z tonight.

In the meantime...expect another day of filtered hazy sunshine
across our Northwoods...with little in the way of cloud cover
expected but plenty of upper level smoke holding overhead. Weak lake
breeze boundaries may interact with daytime instability to kick off
a few showers and maybe a thunderstorm across interior sections of
Eastern Upper and NE Lower Michigan...but these chances are rather
small and expect overall dry conditions for our CWA today. Afternoon
high temps will warm into the 80s across our entire CWA. Overnight
lows will cool back into the upper 50s and lower 60s.

&&

.SHORT TERM...(Tuesday through Wednesday)
Issued at 345 AM EDT Mon Jul 19 2021

High Impact Weather Potential: Minimal attm...

Pattern Synopsis/Forecast:

Could almost cut and paste the start of last night`s short term
discussion...as the troughing off the coast of British Columbia
will be holding on...and anomalously strong ridging will be
holding on as well ahead of it, through the western US/Canada. Here
in the Great Lakes region...will be looking for a weak niblet of
energy to be dropping through the flow into our area...which should
serve to kick off a chance for showers and storms...as well as sweep
cooler...drier...and perhaps less smoky air into the region (as the
upper level flow should shift more north to northeasterly, away from
the core of the fires to our northwest near Lake Winnipeg in
Manitoba/western Ontario). Ridging may briefly return to our fair
state for a time Tuesday night into Wednesday...but by late
Wednesday...another, stronger niblet of shortwave energy will be
poised to our north/northwest...which should act as the next impetus
for precipitation going into the tail end of the short term...and
start of the long term.

Primary Forecast Concerns: Rain/storm chances Tuesday and again
Wednesday night...temperatures Tuesday...

Uncertainty continues regarding exact timing/placement of the front
Tuesday morning...as some guidance is still a bit quicker with
it...bringing cooler 850mb temps as far south as the Tip of the Mitt
by Tuesday morning. This particular piece of guidance has less
moisture aloft...which would indicate diminished potential for
precipitation Tuesday. Given that guidance may be having a tricky
time with initial mid-level moisture tonight...similar to last night
(though looking a little better than last night)...will tend to side
with drier guidance. (Do note that today`s guidance seems to be
generally trending quicker and somewhat drier with the front as
well...at least initially, anyway.) Still...hard to ignore the
potential for some showers and storms, as there will be a front
dropping in, associated with some low-level moisture. Better chances
for more vigorous showers and storms would likely be toward our
south/southeastern CWA Tuesday afternoon...ahead of the front, where
more daytime heating should (in theory) take place...though there is
still potential right along the front as it drops in from north to
south Tuesday morning into the afternoon. As winds aloft pick
up some with this system...will have to watch out for a) additional
lift (with a weak upper-level jet max dropping in that could lend to
a tad more synoptic lift...but we`ll see...), b) gustier winds to
mix down to the surface, especially with any showers/storms, and c)
perhaps a rogue marginally intense storm, though severe potential
attm looks pretty low, given progged shear values generally running
around 25-35kts (which would typically preclude supercell
development).

With a brief return to ridging Tuesday night into Wednesday behind
the shortwave trough...and as high pressure drops in from the
north...will expect things should be cool and dry. Going into
Wednesday night, however...especially towards midnight or so...mid
and low level moisture should be on the increase again...ahead of
the next shortwave trough diving south through the flow. There is
uncertainty with the position and depth of this trough...as a
slightly deeper solution with a sharper trough could be more
dynamically favorable for precipitation development...as lift
overlaps mid and low level moisture. Did note last night that model
guidance may be trending a little slower with bringing precipitation
into the area Wednesday night...so there is a chance it could hold
off until closer to daybreak Thursday.

As mentioned, the other major concern with the forecast will be
temperatures Tuesday...which will rely heavily on the
timing/position of the cold front. Will continue with the idea of
the last two nights...of cooler temps north, where there is a better
chance of the cold front having passed through earlier in the
day...and warmer temps towards the south and southeast...where it`s
more likely to have warmed up ahead of the front. As discussed in
last night`s discussion, however...quicker fropa would lead to
cooler temps down that way as well.

.LONG TERM...(Wednesday night through Sunday)
Issued at 345 AM EDT Mon Jul 19 2021

High Impact Weather Potential: Minimal attm...

As hinted at in the short term...the start of the long term has
potential to be somewhat active...as a more potent shortwave drops
in from the north along the flow. There is still some uncertainty in
the depth/sharpness of the shortwave trough...but it is certainly
something to keep an eye on...as there are some hints that it could
be a better chance for showers/storms than what we`re expecting for
Tuesday. Though there seems to be agreement in the overall idea of
troughing trekking through the Canadian prairies, trying to cut the
top off the ridge...and troughing holding on across the northeastern
US...there is a fair bit of uncertainty in the exact evolution and
resultant details. Therefore...will stick with consensus guidance
for the bulk of the long term...as there is too much uncertainty to
get too cute with that timeframe attm.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 645 AM EDT Mon Jul 19 2021

High pressure currently centered over the Great Lakes will
gradually slide south as a weak moisture-starved cold front pushes
out of Ontario and into Northern Michigan late tonight. This front
will bring small chances of showers and thunderstorms to far
Northern Lower Michigan after 06Z tonight...but the chances are
too small to include in the PLN TAF for now. Otherwise...solid VFR
conditions will persist at all Northern Lower Michigan TAF sites
thru Tuesday morning. Surface winds will remain from the NW AOB 10
kts.

&&

.MARINE...
Issued at 345 AM EDT Mon Jul 19 2021

Winds and waves will remain below SCA criteria thru Tuesday despite
the passage of a weak cold front later tonight and Tuesday. Small
chances of showers and thunderstorms will enter our forecast late
tonight into Tuesday as this front slides thru Northern Michigan.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...MR
SHORT TERM...FEF
LONG TERM...FEF
AVIATION...MR
MARINE...MR