Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 042336
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
636 PM EST Sun Dec 4 2016

.NEAR TERM...(Tonight and Monday)
Issued at 356 PM EST Sun Dec 4 2016

High impact weather potential: Light to moderate snowfall through
tonight. Slippery roads.

Pattern synopsis and forecast:

Upper trough continues to become more negatively tilted as it works
into the western Great Lakes, with the associated sfc low crossing
nrn MN and a sfc trough pressing through the Mississippi. Forcing is
increasing via left front exit region jet dynamics and strong DPVA,
while deeper Gulf moisture feeds into the system. PWATS have
increased a little higher than thought yesterday, to near 0.60". The
strong deep layer forcing is evident in expanding >24 dbz echoes
along and south of M-72. This is also the region where there were
hints of strong lift in the DGZ, for bigger flakes/higher snow
ratios and better accumulations. The onset of the precipitation has
primarily been snow, as wet bulb effects/evap cooling quickly
brought middle 30s temperatures down into the lower 30s.

The upper trough lifts through nrn Michigan tonight with mid level
ridging settling in Monday. Snowfall will spread across all of nrn
Michigan over the next few hours, with a continuation of feeding two
areas of lake effect snow showers that have been going on since this
morning. One area in across western Mackinac county, and the other
in eastern sections of Chip/Mack, up the St. Mary`s. The signals for
strong lift in the DGZ continues in the evening as the upper
divergence and DPVA continue. Did increase snowfall amounts to 2-4"
with potentially higher amounts in those lake enhanced areas of
eastern upper. Still tough with some melting going on into evening,
and since snowfall rates are not expected to reach an inch per hour
for very long periods of time, getting a quick couple inches on the
ground to help will not be the rule. Roads will gradually become
snow-covered and slippery.

Snow will end late this evening across the GTV Bay region, and the
remainder of the region overnight, from SW to NE as the deeper
moisture aloft strips out, and the top of the moisture sinking below
-10c. Could see precipitation ending as a little drizzle/freezing
drizzle, especially in the higher terrain due to orographic lift in
developing westerly flow. There is also the increasing likelihood of
weak westerly flow lake effect into Monday morning, impacting far
nrn lower. Things try and dry out heading through Monday, maybe some
sun, but stratus and incoming higher cloud from the next shortwave
will already be moving in in the afternoon.

&&

.SHORT TERM...(Monday night through Wednesday)
Issued at 356 PM EST Sun Dec 4 2016

...Colder air begins to ooze in later Tuesday into Wednesday...

It looks like it will take a couple of days but a change in the
pattern is shaping up for the middle and end of next week. This will
be in the form of a trough across the Great Lakes, along with colder
air and lake effect snow. The main short term forecast concern
revolves around when the lake effect machine will be turned back on.

Monday night into Tuesday...Northern Michigan will be squarely
between a northern stream wave moving by to our northwest and low
pressure moving by to our southeast. Meanwhile, warm advection
should put an end to any lingering southwest flow lake effect off of
Lake Michigan Monday evening (which would mainly effect eastern
upper). Low chance pops on Tuesday (for rain or snow showers) from
the combination of the two systems but not much if any actual
precipitation is expected at this point. Cold advection will begin
late in the day as the low pressure system moves by to our
southeast.

Tuesday night into Wednesday...Steady cold air advection as the
incoming upper trough drops heights. It will turn cold enough for
chances for what looks like west southwest flow lake effect
Wednesday. However, models vary on the timing of the cold air as
well as the exact flow and amount of moisture (which looks limited
initially). Better moisture/over lake instability arrive Wednesday
night and especially on Thursday (see below). Temperatures will
remain well above normal through Wednesday.

.LONG TERM...(Wednesday night through Sunday)
Issued at 356 PM EST Sun Dec 4 2016

High Impact Weather Potential...Accumulating lake effect.

Primary concern through the extended remains the prolonged lake
effect snow possibilities. Cold H8 air will move overhead behind a
mid-week system, getting progressively colder going into the
weekend. Winds continue to remain NW for a couple of days before
backing to SW by Sunday. This will increase accumulations for NW flow
snow belts. Also seeing further enhancements in the form of
shortwaves moving through the flow that could increase accumulations
for some. This push of cold air will also bring below normal
temperatures, something we haven`t seen much of so far this year.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 634 PM EST Sun Dec 4 2016

Snow continues to fall with widespread IFR conditions across
northern Lower Michigan this evening...and should continue through
midnight before tapering off perhaps to a period of drizzle or
freezing drizzle. Flight conditions expected to improve to MVFR
after daybreak Monday.

&&

.MARINE...
Issued at 356 PM EST Sun Dec 4 2016

Rain and snow will continue into the evening, ending from SW to NE
late this evening through daybreak Monday morning. Southerly
winds will turn westerly by Monday with sporadic low end advisory
level speeds. Winds turn back southerly later Monday and Monday
night as low pressure lifts into srn Canada. Additional advisories
likely for Lake Michigan and Whitefish Bay, and again Tuesday and
through much of the remainder of the work week, in cold advection
and unstable conditions.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until 4 AM EST Monday for MIZ008-015.
LH...SMALL CRAFT ADVISORY until 1 AM EST Monday for LHZ348-349.
     SMALL CRAFT ADVISORY from 1 AM to 1 PM EST Monday for LHZ345.
LM...SMALL CRAFT ADVISORY until 1 PM EST Monday for LMZ323-342-
     344>346.
     SMALL CRAFT ADVISORY until 1 PM EST Monday for LMZ341.
LS...SMALL CRAFT ADVISORY until 7 PM EST this evening for LSZ321.
&&

$$

NEAR TERM...SMD
SHORT TERM...AJS
LONG TERM...ALM
AVIATION...JPB
MARINE...SMD



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