National Weather Service - Area Forecast Discussion

000
FXUS63 KAPX 190655
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
255 AM EDT Tue Mar 19 2024

.KEY MESSAGES...

- Accumulating snow this morning, especially far northern lower and
  eastern upper Michigan.

- Lake effect snow and gusty winds ramp up late today through
  Wednesday.

- Increasing potential for more snow on Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Pattern Synopsis/Forecast: Deep upper-level troughing currently
anchored over eastern Canada southward over the eastern seaboard.
Northwest flow aloft across the western Great Lakes into the
upper MS Valley and northern Plains. A couple of weak embedded
perturbations within this flow regime progged to cross the
region today and tonight. At the surface, low pressure centered
north of Lk Superior early this morning will gradually drift by
to our north today...progged near the Qc/On border by 12z
Wednesday. This will allow for a cold front to cross the
forecast area from northwest to southeast today.

Accumulating snow this morning: Pretty widespread light snow ongoing
early this morning, especially over the eastern U.P. and far
northern lower. These areas are still where the primary
accumulations are anticipated through midday with 1-3" near and
north of M-32. Some locally higher amounts not entirely out of the
question in southwest flow lake enhancement areas downwind of Little
Traverse Bay and across far southeast Mackinac/Chippewa counties,
including Drummond Island. Low probabilities in those areas to wring
out 3.5-4". Not much in the way of gustiness with the primary
impacts through midday being snow-covered/slick roads, including
during this morning`s commute.

Lake effect snow/gusty winds ramp up late today: Winds veer west-
northwesterly later this afternoon behind a passing cold front. Cold
advection to follow with a transition to lake effect snow. This
transition occurs first in the eastern U.P. given an initial colder
airmass and longer Lk Superior fetch. That transition doesn`t really
materialize much south of bridge until this evening with increasing
coverage of snow showers after 00z. Increasing gustiness through
this time frame, especially overnight, with gusts of 20-30 mph
becoming common after 06z. Highest additional accums this evening
through tonight expected across Chippewa County in the eastern U.P.
of 1-4" with some localized 1-2" amounts south of the bridge in
the typical WNW/NW flow snow belts from eastern Grand Traverse
County northeastward to Otsego County.

&&

.SHORT TERM /WEDNESDAY/...
Pattern Synopsis and Forecast:

Vigorous short wave/vort max/clipper will be impinging on the region
Wednesday as a cold, somewhat moist, low level airmass settles
across northern Michigan. Sub 1000mb cyclone will move to the east
through the day across Quebec, tightening the pressure gradient and
increasing the low level winds. Lake effect snow the main concern
through this period in addition to gusty northwest winds combining
for hazardous travel across NW snow belts.

Primary Forecast Concerns:

Lake effect snow likely ongoing by Wednesday morning (esp E UP) as
quick moving clipper/vort max dives southeast across N MI and cold
low level temperatures ooze over the "warm" Great Lakes. Progged
soundings Wednesday show modest/decent inversion heights (750-850mb
depending on location and timing) and moisture depth, although lower
portions of the boundary layer appear to be somewhat drier at times
across northern lower, esp Wed afternoon. Another caveat, as the
trough (both aloft/lower levels) propagate east/southeastward into
Ontario/Quebec, lake effect banding will likely shift and propagate
southward as well. Thus, although the thermodynamic profiles suggest
at least the potential for heavy periods of snowfall, resonance time
of said bands might not be long enough to significantly accumulate.
Where bands do remain persistent, however, the potential does exist
for several inches of snow across northwest snow belts, especially
Chippewa county (Whitefish Bay and vicinity likely best chance for
accumulating snowfall), and to a lesser extent Antrim, Otsego,
Kalkaska, and Crawford counties. In fact, NBM&HREF 90th percentiles
show ~3-5" in this general area, little bit better potential in
Chippewa. Supplement this with several other deterministic guidance
showing the potential for moderate accumulation/several inches of
snow and this suggests the potential for accumulating snow on
Wednesday (Tuesday evening into Wednesday really). Highest accums,
potential for moderate amounts, will be Chippewa county, and
generally a little less across northern lower. Pressure gradient
will tighten as the aforementioned troughing and attendant sfc low
move east, thus wind gusts will likely be in the 30-35 mph range as
well on Wednesday (with temps in the 20s...brrr). Concern will be
heavy falling lake effect snow with these winds resulting in
significant reductions in visibility and hazardous travel. Lighter
lake effect will linger into early/midday Thursday as cold
temperatures remain.
&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Pattern Synopsis and Forecast:

Another snow event is likely on Friday. Upper level energy will
swing into portions of the Great Lakes/Upper Midwest within a warm,
moist advection regime (at least during the day on Friday). As a
result, precipitation will overspread the region, focusing south of
M-32. Still some discrepancies within model guidance. GFS remains
quite robust suggesting a moderate to heavy wet snow event. Cannot
deny the trend in ensembles over the past few days with increased
snow total means/percentiles. Quick look at latest NBM suggests this
is an event worth watching, the exact progression of the upper level
pattern and subsequent placement of the precipitation shield will be
crucial. Will be the difference between a light and moderate/heavy
snow event, for some areas. All this being said, the best chance for
accumulating snow will be south of M-32 as guidance has been hinting
at. Active period of weather likely to remain later Sunday through
the early-mid portions of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Snow associated with a clipper system falls tonight into Tuesday
morning, most prominently at CIU/PLN. Primarily MVFR conditions
in this snow, but drops to IFR possible in steadier snow. Snow
coverage diminishes later this morning with renewed lake effect
snow chances arriving late Tuesday afternoon into Tuesday
evening. Ongoing breezy southwest winds this morning veer west-
northwesterly this afternoon.

&&

.MARINE...
Some sporadic low-end Small Craft Advisory winds/waves anticipated
on northern MI`s nearshore waters today with more solid advisory
conditions anticipated to ramp up tonight through Wednesday. Very
late tonight into Wednesday also features low probabilities for some
low end sporadic gale gusts, primarily on far northern Lake Michigan
and Huron.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 5 PM this afternoon to 8 PM EDT
     Wednesday for LHZ345>348.
     Small Craft Advisory until 4 PM EDT this afternoon for LHZ349.
     Small Craft Advisory until 8 PM EDT Wednesday for LMZ323-341-
     342-344>346.
     Small Craft Advisory from 2 PM this afternoon to 8 PM EDT
     Wednesday for LSZ321-322.

&&

$$

NEAR TERM...MJG
SHORT TERM...JLD
LONG TERM...JLD
AVIATION...MJG
MARINE...MJG

NWS APX Office Area Forecast Discussion