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771
FXUS63 KAPX 070346
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1046 PM EST Fri Dec 6 2019

.UPDATE...
Issued at 930 PM EST Fri Dec 6 2019

Lake effect snow showers continue to gradually diminish in
coverage and intensity. Not much more than flurries left in
northern lower MI; activity poking into eastern upper MI is a
smidge healthier. High pressure in se Iowa will progress east,
passing to our south in the morning. 1000-850mb winds are already
starting to back, and the Superior connection into northern lower
MI has already been severed. A wsw fetch will be in place by
morning. That is at least a longer fetch on Lake MI; though
Superior activity will cease, there is an opportunity for an
uptick off of Lake MI. This will be especially the case very late
(toward morning), when a shortwave arrives and interacts with
developing warm advection. We already see some virga/very light
snow well upstream over ne MN/far nw WI, and this should continue
to slide ese-ward toward northern Lake MI overnight.

There have been enough breaks in the lake-induced cloud cover to
lower temps into the teens in some spots (CAD/GLR). Current min
temp forecast appears suitably chilly, and no major changes were
made.

&&

.NEAR TERM...(Through Tonight)
Issued at 321 PM EST Fri Dec 6 2019

...Diminishing lake effect tonight...

High Impact Weather Potential: None.

Pattern Synopsis/Forecast: Afternoon surface analysis reveals lake
aggregate troughing across southeast Lake Superior down into
Georgian Bay with northwesterly flow still intact down through
Lower Michigan. NW flow lake effect snow showers persist. Overall
light, but there are still a few heavier lake bands off Superior
into parts of Chippewa county as well as down into parts of
northern Lower Michigan, the most persistent and heavier of which
crosses down through Antrim and Kalkaska counties.

Upstream, elongated axis of surface high pressure extends from
the far western Great Lakes down through west Texas and is
steadily building eastward into the region. This is another weak
wave and area of warm advection/enhanced cloud tops sliding out
of south-central Canada into the Upper Midwest that will move
through northern Michigan later tonight into Saturday morning.

Primary Forecast Concerns: Minimal overall. Lake effect trends.

Diminishing lake effect snow showers are still anticipated as we
head through the evening as surface high pressure, weakening and
backing low level flow take their toll. But a few locations could
yet see some light accumulations this evening. Then, aforementioned
upstream weak wave and area of warm advection forcing will track
through northern Michigan overnight into Saturday morning. This
system does not pack nearly the punch that last nights system did.
In fact, I can`t find any upstream station reporting precip at
this juncture. But, increasing cloud cover/moisture aloft and
uptick in inversion heights should bring renewed lake effect snow
showers into parts of the area. Specifically, areas along the Lake
Michigan shoreline and up through the Straits into parts of
eastern Upper Michigan as low level mean flow swings southwesterly.
Those areas might see an inch, maybe two, tonight and Saturday
combined snow accumulations.

&&

.SHORT TERM...(Saturday through Monday)
Issued at 321 PM EST Fri Dec 6 2019

High Impact Weather Potential: Minimal

An upper-level trough to the east will exit off of the New England
coast as another trough amplifies in central Canada. This will help
deepen a cyclone formed in lee of the Canadian Rockies into the
Hudson Bay area, swinging an associated cold front down across the
US/Canada border in the northern Great Plains late Sunday. As
surface high pressure departs to the east of the Great Lakes through
the weekend, enhanced southerly flow along the back end could bring
above freezing temps to the area out ahead of the cold front.

Relatively warm lake temps combined with low to mid-level warm air
advection could produce some more light snow across far northwest
lower/tip of the mitten/eastern upper MI into the evening Saturday
amidst a short window of supportive moisture in the region. A chance
for more light snow exists early Sunday morning across eastern
upper, but accumulations for both of these rounds are expected to be
near an inch or less. As previously mentioned, temps could climb
above freezing for a time Sunday afternoon for most. However,
portions of interior northern lower and eastern upper may struggle
to do so in higher elevations. While widespread precipitation isn`t
expected largely until Monday, this warm up would provide a
timeframe for a transition to a rain/mix for some areas before
cooling down again Sunday night.

.LONG TERM...(Monday night through Friday)
Issued at 321 PM EST Fri Dec 6 2019

High Impact Weather: Potential winter storm early week, along
with frigid temps and lake effect to follow.

Sunday night, an upper-level jet max across the southern Great
Plains will help develop a lee cyclone that will deepen and move to
the northeast along the aforementioned boundary into the Great Lakes
region Monday. Uncertainties in forecast strength and track
prohibit specific details at this time. However, rain, snow, and
gusty winds are expected to impact northern Michigan through
Tuesday with this system. The potential for a wintry mix exists,
but latest model guidance hints towards more rain/snow at this
time. Details regarding areas of greatest impacts and snow
accumulations will be more clear as the event draws closer. Frigid
temps are expected behind this system with high temps in the
teens and lows in the single digits with wind chills potentially
below freezing through the end of the week. West to northwest
winds will likely bring additional lake effect snow to northern
Michigan during this time as well.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1046 PM EST Fri Dec 6 2019

MVFR cigs at times, mainly PLN/MBL and perhaps TVC.

High pressure moving into western IL will pass to the south of MI
Saturday morning. Lake effect clouds and snow showers have been
decaying. However, an uptick is expected toward dawn, as a weak
upper level disturbance lends a hand. Some snow showers will be in
the vicinity of MBL/PLN/TVC at times in the morning, and cigs will
ride the border between VFR and MVFR. Cigs will improve later in
the day.

Light winds overnight will become ssw Saturday. Those winds will
be gusty at times in the afternoon evening, and LLWS will develop
late in the evening.

&&

.MARINE...
Issued at 321 PM EST Fri Dec 6 2019

Gusty northwest winds diminish tonight and back west/southwesterly
heading into Saturday. Current small craft advisories run through
this evening and will likely be allowed to expire as advertised.
But, southwest winds ramp back up later Saturday and especially
Saturday night into Sunday and gale force gusts are looking
likely for Saturday night into Sunday on Lake Michigan. Plan to
maintain the gale watch for now. Later shifts can upgrade to a
warning as we get closer to the event.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 1 AM EST Saturday for LHZ345>349.
LM...GALE WATCH from Saturday evening through Sunday afternoon for
     LMZ323.
     GALE WARNING from 9 PM Saturday to 5 PM EST Sunday for LMZ341-
     342-344>346.
LS...NONE.
&&

$$

UPDATE...JZ
NEAR TERM...BA
SHORT TERM...DJC
LONG TERM...DJC
AVIATION...JZ
MARINE...BA