000
FXUS63 KAPX 290800
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
400 AM EDT Tue Sep 29 2020

.NEAR TERM...(Today through Tonight)
Issued at 400 AM EDT Tue Sep 29 2020

...Remaining unsettled and cool...

High Impact Weather Potential: Potential for waterspouts
increases again late tonight into Wednesday.

Pattern Synopsis/Forecast: Deep trough axis continues to carve out
across the western Great Lakes and down through the Mississippi
River Valley early this morning along with several embedded waves
pinwheeling through the mean upper trough. Lead wave and
attending deepening surface low is progressing up into eastern
Ontario while main surface cold front is pressing into the east
coast. Another piece of short-wave energy is sliding down through
the Chicago area while yet a third wave is diving southeastward
into western Ontario.

Wedge of deep layer dry air has been building across the region
over the last several hours and did manage to clear out a fair
amount of cloud cover during the overnight. But with the arrival
of colder air across the warmer lakes (H8 temps down to around
+3C) and lingering larger scale troughiness, spotty showers
remain, primarily downwind of the lakes in upper Michigan and NW
Lower Michigan.

Large scale trough will continue to be reinforced/deepen across the
Great Lakes over the next few days as additional short-wave energy
gets dumped out of Canada into the mean trough...capped off by a
reinforcing shot of still colder air for Thursday and Friday. Upshot
to this, unsettle/showery weather will continue pretty much through
the week.

Details: All things considered, not too bad of a day today as
wedge of deeper layer dry air works across the region. Ongoing
lake induced spotty shower activity will probably continue
however, becoming more focused up through the tip of the mitt as
low level mean flow backs southwesterly in time...in advance of
our next short-wave. In addition, with cool air aloft and late
September heating, there may be enough instability to pop some
spotty showers across north central and northeast Lower Michigan
this afternoon. But again, overall...not too bad of a day with
some sunshine and high temperatures reaching the upper 50s to
lower 60s.

Meanwhile, upstream Canadian short-wave trough will dive into the
western Great Lakes this afternoon and cross the forecast area
tonight. Increasing larger scale forcing for ascent, cold air and
steepening lapse rates aloft will once again lead to expanding
showers across much of the CWA, but especially downwind of lakes
Superior and Michigan where lake induced CAPE values climb to
several hundred J/Kg per BufKit soundings. Once again, would not
be surprised to see a few thunderstorms develop on Lake Michigan
and press into the shoreline areas. Will introduce TSTMs to the
forecast for the immediate Lake Michigan shoreline areas
accordingly. No severe storms. But...given reduced freezing/wet
bulb zero levels (down around 5-6K feet), some small hail can`t be
ruled out. Also, given potential deeper convective cloud depths
and lake-850 MB temp differences running 10C to 15C, thunderstorm
and/or upper low waterspouts will be possible as well.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 400 AM EDT Tue Sep 29 2020

...Continued Showery and Turning Even Cooler...

High impact weather potential: Low.

Primary forecast concerns/challenges: Pops and thunder
chances through the period.

Unseasonably deep trough continues to dig its heels into the region.
Upper level disturbances pivoting around this trough in combination
with increasing over lake instability will bring more showers to the
region. It still looks unstable enough Wednesday for a few rumbles
of thunder as well. The coldest air of the young season will then be
ushered in by a surface cold front moving through on Thursday
perhaps accompanied by more thunder. All in all the short term looks
rather dismal. Gusty north northwest winds Thursday behind the front
will make it feel even colder. Highs in the mid 50s to low 60s
Wednesday will fall off into the upper 40s to mid 50s Thursday. Lows
in the upper 30s and low 40s.

&&

.LONG TERM...(Thursday night through Monday)
Issued at 400 AM EDT Tue Sep 29 2020

...Remaining Chilly with Additional Rain Chances...

High impact weather potential: Low but the first wet flakes of snow
are possible late Thursday night into Friday morning.

No big letup in the unseasonable chill is expected through the long
term as the upper level trough remains in place. As a matter of
fact, the core of the cold air digs into the region Thursday night
into Friday with 850 mb temperatures dropping all the way down to
between -4 C (southeast) and -7 C (northwest). This is likely
marginally cold enough for a few wet snow flakes to enter into the
fray and mix in with ongoing lake effect rain showers across eastern
upper and the higher terrain of northern lower. Winds are veering
from northwest into the north or perhaps even north northeast so
expect lake effect to be shifting around. Extended models then track
a surface area of low pressure by to our south this weekend. This
system will increase chances for rain Saturday (and if it were later
in the year it would be snow). Not quite as cold Sunday into Monday
but still well below normal. Perhaps some milder temperatures moving
in just past the scope of this forecast but unfortunately models are
trending away from any big warmup.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1145 PM EDT Mon Sep 28 2020

Low pressure centered northeast of Michigan will slowly lift
northward to James Bay by Tuesday morning. Associated secondary
cold front currently over Lower Michigan will push east of our
state overnight...ushering cooler air into our region. Periodic
showers will continue to impact all Northern Lower MIchigan TAF
sites overnight thru Tuesday night thanks to deep cyclonic flow
and wrap-around moisture in the wake of this system. Overall
conditions will remain low VFR/MVFR thru the 24 hour TAF forecast
period. W/SW around 10 kts will strengthen to 10 to 20 kts with
some higher gusts possible.


&&

.MARINE...
Issued at 400 AM EDT Tue Sep 29 2020

...Cool, unsettled weather continues for the next several days...

Gusty westerly to eventual southwesterly winds will likely keep
small craft advisory conditions going today and much of tonight.
After a brief lull in precip today, shower coverage increases
again tonight and continues through Thursday as reinforcing waves
of low pressure and cold air dive into northern Michigan. This may
lead to a few thunderstorms on Lake Michigan tonight, along with
waterspout potential over the next few days.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until noon EDT today for LHZ345>348.
LM...SMALL CRAFT ADVISORY until noon EDT today for LMZ323-341-342-
     344>346.
LS...SMALL CRAFT ADVISORY until noon EDT today for LSZ321-322.
&&

$$

NEAR TERM...BA
SHORT TERM...AS
LONG TERM...AS
AVIATION...MR
MARINE...BA

NWS APX Office Area Forecast Discussion