041
FXUS63 KAPX 081953
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
253 PM EST Wed Jan 8 2025

.KEY MESSAGES...

- Lake effect snow showers linger into Thursday morning,
  shifting focus from the Lake MI coastline this
  evening/tonight to the western portions of Mackinac and
  Chippewa counties by early Thursday morning.

- Cold temperatures continue through tonight.

- Snow (possibly mixed with freezing drizzle?) Thursday night
  into Friday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 251 PM EST Wed Jan 8 2025

Pattern Synopsis and Forecast:

A longwave trough will continue to swing southeastward through
the short-term as high pressure tries to build in its wake with
its axis reaching the area by the end of the period. A shortwave
trough will track south across the Great Lakes, maintaining
cold temperatures and lake effect snow showers across the
northern Michigan into Thursday.

Forecast Details:

- Today through Thursday lake effect snow showers: Current
  radar indicates lake effect showers focusing on the shoreline
  of Lake Michigan with accumulating snow expected to continue
  into tonight. Trends continue to support the bulk of
  accumulating snow staying offshore of Manistee county with an
  additional 1" to 2" expected for areas near and south of Grand
  Traverse Bay, with the higher amounts focused on the shoreline
  of Manistee county (possible 3" to 4" if the band shifts more
  onshore). NNW winds will shift southwest ahead of a clipper
  system progged to impact northern Michigan Friday. This will
  essentially "shut off" lake effect snow showers across
  northern Lower and refocus them to the western portions of
  Mackinac county late tonight through Thursday as flow becomes
  southerly early Thursday morning. Accumulations are expected
  to be light with generally 1" or less forecasted by Thursday
  night.

- Cold temperatures: Colder air will continue to drain into
  the Great Lakes Region providing below "normal" temperatures
  (approximate normal highs-- mid 20s; approximate normal lows--
  teens) today into tonight. Aggressive clearing is noticed
  across northeast Lower and eastern Upper Michigan on Satellite
  Imagery this afternoon with this trend expected to continue
  through Thursday. With this, tonights temperature forecast is
  a little tricky with how cold it will get, especially where
  aforementioned clearing is occurring and how expansive this
  clearing will be. Current thinking is that temperatures across
  northeast Lower tonight will be in the single digits to
  possibly the negative single digits for the typical colder
  spots, whereas, counties south and near Grand Traverse Bay
  will stay a bit warmer (upper single digits to the teens) due
  to flow becoming southerly quicker and clouds hanging on
  across the area. Temperatures will return to more "normal"
  readings for Thursday, with forecasted highs largely in the
  20s.


&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 251 PM EST Wed Jan 8 2025

PATTERN SYNOPSIS/FORECAST:

Yesterday`s niblet just barely skimmed by to our east...now
located off to our east...as another PV max funnels down from
the north toward the Great Lakes this morning...pinched between
retrograding upper low and northeasterly flow over Quebec...and
northwesterly flow over shortwave ridge axis over the central
Canadian Prairies. Strengthening meridional thermal gradient to
our north...with a meridional warm front over Manitoba on the
warm side of the thermal gradient under the ridge axis. Broader
ridge axis over the western US being overtopped and squashed by
PV niblets crossing through western Canada (one of which is
aiding in the aforementioned warm front)...with 140+kt NWly
upper jet diving down into the PacNW. Upper low still remains in
the vicinity/just south of SoCal, and some additional PV
getting zonally stretched out over the central Plains. High
pressure largely splitting around the Great Lakes (as usual for
this time of year)...with light north flow out of Ontario
leading to temps in the single digits above/below zero this
morning...and dewpoints well below zero over the eastern UP.
Lingering lake effect becoming much more N flow, impacting
mainly coastal areas and TVC.

Shortwave ridging builds in tonight into Thursday...but the
next clipper system will be right on its heels, with return flow
increasing Thursday night into Friday. Looks like this will
slide through and stall a boundary in the vicinity (likely just
to our south) for the weekend...as next niblet in the parade of
PV maxima triggers cyclogenesis over the central Plains. (We
could certainly keep lake effect around into Saturday here in
the Northwoods.) Guidance is in better agreement on the
placement of this today compared to yesterday...attm, pointing
toward the surface low slowly meandering across the Upper
Midwest/Upper MS Valley into the Upper Great Lakes by Sunday
night into Monday. Assuming this idea remains...could need to
watch for p-type issues later Sunday into Monday morning ahead
of this low, if we get enough warm air aloft into the area.
Expectation is for additional upper energy to spin down into the
Midwest early next week, reinforcing the idea of cold air over
the region (ironically, guidance now struggles with the
depth/westward extend of this feature which could throw a bit of
a wrench in the NW LES idea for early/mid week next week
(discussed in yesterday`s AFD)).

Primary Forecast Concerns:

Snowfall (mixed with freezing drizzle?) Thursday night into
Friday...Think southwest flow lake effect/enhancement will begin
to pick up overnight; first, especially up in Western Mackinac
county...but eventually along the Lake MI coast of NW Lower,
too. Guidance soundings suggest some low-end potential for
freezing drizzle, as it may take a bit to saturate things with a
low-level moist layer potentially barely scraping the DGZ.
Think potential is more likely for snow...but can`t rule
freezing drizzle out. This could additionally be the case later
in the day as there are signals for the synoptic moisture to
rather quickly sweep out and/or ramp up over northeast Lower,
rather than NW Lower....which could potentially dry out the
layer with more favorable ice nuclei temps over the lake effect
areas...as winds turn a little more northwest in the wake of the
front in the afternoon. Will need to keep an eye on this going
forward. As far as snow totals go...not a ton in the way of
impacts expected attm. Despite some decent lake enhancement
signals with the incoming synoptic moisture...along with decent
lift and some instability at least as far as the lakes are
concerned...concerns that we may quickly dry out in the mid-
levels could certainly temper the potential for better snowfall
accumulations, as well as potential for SLRs to be a touch lower
given we should be a little warmer with this system. Won`t be
impossible for parts of northeast Lower to pick up an inch or so
of snow with this, either, if that idea of the moisture
advection up the front later in the afternoon comes to
fruition...though SW/NW flow lake effect areas /should/ see the
highest snowfall totals through Friday night.

Sunday/Monday system...This one could be interesting to watch,
noting some signals for weaker stability aloft within the better
moisture. Definitely too soon to put any numbers on this, and
definitely too soon to message this with any kind of confidence,
given that guidance is just now wanting to come into agreement as of
this afternoon. Will certainly be something to keep an eye on as we
go forward, however.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1236 PM EST Wed Jan 8 2025

Expecting light flurries and lake effect snow showers to
continue and slowly shift west with time, focusing accumulating
snowfall along the lake Michigan shoreline. Expecting MVFR
conditions with possible IFR visibilities within some of these
snow showers and lower clouds at KTVC and KMBL. Clearing is
expected to continue across other sites, and eventually KTVC,
leading to VFR condtions. NW to NNW winds will be breezy into
this evening (gusts 10 to 15 knots) becoming light and shifting
southerly for Thursday. One thing to watch is the possibility of
fog development tonight/ tomorrow morning (KTVC and KPLN?) as
winds become light, and southerly flow advects moisture into the
region from the south-- Uncertainty is high on this
possibility, but worth mentioning in this discussion.

&&

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

&&

$$

SHORT TERM...NSC
LONG TERM...FEF
AVIATION...NSC