893
FXUS63 KAPX 250758
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
258 AM EST Mon Nov 25 2024

.KEY MESSAGES...

- Accumulating wet snow expected across the eastern U.P. and
  parts of northern lower Michigan today and tonight. Amounts of
  3-6" with locally higher amounts near 8" possible north of the
  bridge by Tuesday morning.

- Breezy with accumulating snow Tuesday.

- Potential for accumulating snow for Thanksgiving and beyond.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 255 AM EST Mon Nov 25 2024

Pattern Synopsis:

Ridging will continue to slide east of the region this morning with
weak surface high pressure following suit. A northern stream
shortwave pivoting across the northern Great Plains will dig across
the upper Midwest later today, combining with the jet max embedded
in the primary southern stream flow to generate strong forcing over
the Great Lakes this evening into tonight. Said forcing will provide
continued support for a deepening cyclone well to our southwest that
will trek across the lower peninsula later this afternoon into
Tuesday morning.

Forecast/Details:

Accumulating wet snow today and tonight -- The primary focus of the
period will be expected accumulating wet snow across the eastern
U.P. and parts of northern lower Michigan later today through
tonight. Low-level warm advection will increase through the morning
into the afternoon with strengthening flow and apparent veering wind
profiles in forecast soundings below 700mb. While this will help
support light precip on the front end of the approaching system into
the afternoon, steadiest rain/snow is anticipated this evening and
tonight as strongest forcing/steepest height falls overspread the
region. Temperatures are expected to stay in the low 30s for the
eastern U.P. away from the immediate lakeshores today while northern
lower stays milder with temps ranging from the mid-30s across the
interior higher terrain to upper 30s/low 40s elsewhere. With lighter
precip through the day, rain is expected for most areas south of the
bridge with the potential for some snow to mix in across the
interior higher terrain. Snow may even be the primary precip type
through the AM before temperatures warm a few degrees above freezing
during the afternoon. Meanwhile, colder temperatures across the
eastern U.P. will support all snow for most areas through the period.

Forecast Snow Amounts Today - Tonight (7 AM Today - 7 AM Tuesday):

* Eastern Upper: 3-6" with locally higher amounts near 8" possible.
  Worst conditions this evening into tonight.

* Tip of the Mitt: T-3" with locally higher amounts near 4"
  possible. Worst conditions this evening into tonight.

* Northern Lower higher terrain: 0-2" with locally higher amounts
  near 4" possible. Most accumulations expected after midnight with
  lake effect snow beginning late.

* Northern Lower lower terrain: 0-0.1"

Highest accumulations are anticipated north of the bridge in
conjunction with coldest temperatures and most favorable forcing.
Forecast soundings display nearly isothermal profiles in the lowest
6-10kft between 3-5 C, which may be warm enough to support larger
flakes like dendrites for a time rather than columns/needles with
high humidity in place -- primarily within highest precip rates this
evening. Wet dendrites could make accumulations/SLRs more efficient
for a several hour period during the evening hours across the
eastern U.P./Tip of the Mitt. Highest snowfall rates of 0.5-1" per
hour may lead to quick accumulations of wet snow and reduced
visibility, making for hazardous travel conditions. Worst conditions
are most likely between 5 PM and 10 PM this evening. Highest
uncertainty at this time regarding snowfall accumulations is across
the Tip of the Mitt/interior northern lower this evening. Current
confidence is that a few inches will fall across parts of this area,
but not enough to warrant advisories at this time -- but may need to
be reconsidered in future forecast cycles based on the latest trends
in temperatures.

Otherwise, light snow is expected to taper with time across the
eastern U.P. and parts of NE lower into Tuesday morning. During this
time, northwest winds on the backside of the departing system will
usher in below-freezing temps and kick off lake effect snow showers
across parts of northwest lower later tonight.


&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 255 AM EST Mon Nov 25 2024

PATTERN SYNOPSIS/FORECAST:

Upper trough remains fairly steadfast over the eastern continent,
trying to retrograde over Quebec. Meanwhile...col region from
yesterday has slipped eastward...as ridge axis moves overhead...in
advance of shortwave troughing crossing the central US/Canada...with
additional energy back over the PacNW and off the coast. Core of
central continent troughing focused over Manitoba...with axis
stretching back into the Desert SW. Abundant difluence and
increasingly deep moisture over the length of the MS Valley; main
focus of warm advection remains to our south over the OH Valley on
the nose of a 100-120kt upper jet...where a warm front is
located...though some theta-e advection present over WI...along an
inverted trough axis extending from IA northward to a low over
Manitoba. Cold advection remains focused over the Plains, behind
a cold front draping from the low over IA down into the TX
Panhandle vicinity. Closer to home...mid-level radar returns over
parts of NW Lower finally starting to make it to the ground as of 4z
(stout mid/low level dry layer, per 0z sounding, slowing precip
onset).

Expecting shortwave trough to lift through the region
today...leaving us on the backside of the system and somewhat under
the vicinity of that inverted trough going into Tuesday...which is
when we expect some lake effect rain/snow to develop, with potential
for some accumulations over interior areas in the favored snowbelts.
Things briefly quiet down for the Great Lakes for Wednesday, though
will have to keep an eye on some warm advection activity along a col
region to our south (not to mention the lakes have been
activated)...but the next bit of activity will already be brewing to
our west. Nearly zonal trough axis over the Intermountain West to
start to slip eastward across the Plains Wednesday as additional
energy sinks in out of Canada; current expectation is for the tail
end of this to kick off development of a surface low over the
central Plains...though I suspect we will be near enough to what
lingers of the old boundary/inverted trough from the first system
that we may not be entirely quiet here in the Northwoods.
Aforementioned surface low currently expected to cross the eastern
US, though track attm is unclear dependent on strength of a lobe of
energy tracking through the longer-wave pattern. Either way...the
pattern supports a cold air outbreak across the Plains for
Thanksgiving and beyond...with increasingly northwest flow over the
Upper Great Lakes, suggesting an increased potential for lake effect
snow up here for the long holiday weekend.

Primary Forecast Concerns:

Breezy with accumulating Snow Tuesday...Strong mid/low-level cold
advection expected Tuesday behind the surface low:  W to WNW winds
sustained 10-20kts; gusting as high as 25-30kts in a few spots. Will
have to keep a close eye on this, though...as there is some
uncertainty in where the jet core will focus (closer to M-20 or
closer to M-55?), which could become a little problematic...as it
could lead to the potential for even higher gusts than currently
anticipated, particularly if more vigorous lake convection ends up
deep enough...though do have to wonder if models are suspiciously
ramping the mid-level winds above the cloud-top inversion (sort of
like that warm front situation we sometimes run into...but up around
5-8kft or so rather than 500-1000ft). Either way, do suspect these
stronger winds could drive lake effect bands further inland than
"normal"...so parts of NE Lower could have a shot at seeing some
precip. Not impossible some areas could see a bit of freezing
drizzle where inversion heights will be shallower and potential for
ice nucleation is somewhat lowered...but more likely we`ll be
looking at snow for most areas.

Otherwise...setup is favorable for a vigorous punch of lake effect
precip (with increasing potential for snow over a rain/snow mix,
save for near the immediate coasts), particularly with a bit of
energy crossing part of the area Tuesday morning/midday...which
could intensify/organize lake effect showers for a time. Think that
the focus will be the typical WNW flow bands, perhaps turning a bit
more W with time in the afternoon/evening as the winds begin to
shift behind the aforementioned PV max. Given that this will be
during the day...have suspicions convection will be more cellular
rather than banded...which could lead to dramatic changes in
visibility and road conditions both in time and space through the
day (as my dad says, if you don`t like the weather in Michigan, wait
twenty minutes or move twenty feet...). While parts of NW Lower
should be more favored for snow Tuesday compared to Monday...do
think the EUP will again be a sneaky winner...as the setup is also
quite favorable for parts of Chippewa county to get decent lake
effect snow, potentially with deeper inversion heights/more vigorous
convection...in an area that will have already seen some
accumulations from today.

Potential for accumulating snow for Thanksgiving and
beyond...General pattern of troughing settling into the Great Lakes
Thursday and beyond suggests we will be looking at an extended
period of lake effect snows from Thursday/Friday right on through
the weekend...primarily somewhere between W to NNW flow...which
should favor NW Lower MI and parts of the EUP. I have tempered pops
for the extended, though, just based on the fact that there will be
niblets moving through the flow that could shift the foci of the
heaviest snows through the period...and it isn`t clear yet
when/where/how these will evolve. In advance of the primary lake
effect event, do think there is potential for some kind of warm
advection/fgen banded activity across parts of the Midwest Wednesday
along the col region poised likely to our south, and as that niblet
approaches from Canada...and will have to keep an eye on this as we
go forward to see if it is able to sneak into our southern zones.
Additionally...if the developing surface low ends up tracking
further north into the OH Valley, it may not be impossible that at
least the southern portions of our area could see some more
widespread/synoptic impacts than currently expected leading up to
Thanksgiving and perhaps during the day itself. It will also feel
dramatically colder than we`ve been used to...even with the Lakes
moderating our temperatures...especially with signals for a tight
pressure gradient and subsequent breezy conditions ahead of the cold
surface high dropping into the Plains. The increasingly cold air
will also make it more likely for snow to stick.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1145 PM EST Sun Nov 24 2024

Low pressure will eject out of the Central Plains overnight and
will ride thru Lower Michigan on Monday. Widespread rain and
snow will develop ahead of and around this system...impacting
all of Michigan over the next 24 hours. Prevailing conditions
will deteriorate from low VFR/MVFR to IFR as this mixed precip
develops from SW to NE overnight into Monday. Surface winds
will become easterly and strengthen to 10 to 20 kts with some
higher gusts expected.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory from noon today to 7 AM EST Tuesday
     for MIZ086>088-095-096.
MARINE...Small Craft Advisory from 10 AM this morning to midnight EST
     tonight for LHZ345>348.
     Small Craft Advisory from 10 AM this morning to midnight EST
     tonight for LMZ342.

&&

$$

SHORT TERM...DJC
LONG TERM...FEF
AVIATION...MLR