Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 102032

Area Forecast Discussion
National Weather Service Gaylord MI
332 PM EST Sat Dec 10 2016

.NEAR TERM...(Tonight)
Issued at 327 PM EST Sat Dec 10 2016

...More snow concerns tonight...

High Impact Weather Potential: Return of more general widespread
light snow late tonight.

Pattern Synopsis/Forecast: Cold anomolies continue across the area,
as does what is now becoming southwest flow lake snows. Slow, but
steady, downward trend noted with those lake snows as upstream slug
of dry air continues to filter across the big waters. With that
said, still some decent banding structures noted along the M-68
corridor, with hints of brief periods of near one inch per hour
snowfall rates embedded in such. Transient nature of more intense
snow showers limiting accumulation potential, but would not be
surprised if some areas pick up another few inches this afternoon.
Low/mid level drying will continue to make steady progress into the
region the remainder of this evening as elongated high pressure
briefly builds overhead. Winds continue to back in the process,
targeting better snow shower potential closer to the Lake Michigan
shore (with minimal additional accumulations expected).

Break in the real active weather is indeed a very short one, with
elongated waa driven wing of light snow already breaking out through
the Corn Belt, well ahead of multiple waves ejecting out of the
Intermountain West. These snows will make a run into our southwest
areas later tonight...the beginning stages of another round of
accumulating snow for Sunday and Sunday night.

Primary forecast concerns: Addressing linger lake snow threat as
well as approach of that expanding upstream snow shield.

Details: Conditions for organized lake effect snow definitely turns
more hostile this evening with quickly lowering inversion heights
and drying low levels. Simple inertia and lake/air temperature
difference will no doubt keep lighter lake snow showers going,
increasingly targeting the immediate coast of northwest lower
Michigan as well as up into the Straits. Simple persistence of
activity likely to bring some additional minor accumulations (an
inch or two). Trends overnight support light and disorganized wind
fields, perhaps supporting lingering lake snows to push offshore.
Attention becomes increasingly focused on that approaching wing of
waa snow, which per a consensus guidance blend, should begin to push
into our southwest areas late tonight. Best snows look to remain
upstream, waiting to arrive Sunday morning.


.SHORT TERM...(Sunday through Tuesday)
Issued at 327 PM EST Sat Dec 10 2016

Sunday and Sunday night...

Hi-res models show low level winds shifting to the SE Sunday
morning, pushing lingering lake effect snow bands out over Lake
Michigan and over eastern Upper (where they will diminish).
Meanwhile, widespread snow will overspread northern Michigan from
southwest to northeast as a broad area of intensifying isentropic
lift moves into the Great Lakes region. The area will also be under
the right entrance region of a 300 mb jet streak, which will provide
enhanced synoptic scale lift. Models have been in decent agreement
with the track and timing of this system and in keeping the heaviest
precipitation across our southeastern counties. Another curious
feature that the GFS/NAM/ECMWF/CMC and even some hi-res guidance all
have in common to some extent (but especially the GFS) is a relative
minimum in QPF over mainly northern Lower, possibly due to either
the higher terrain, latent heat influence from the lakes, or a
combination of both. Not overly confident that this artifact will
actually pan out, but it`s hard to completely dismiss with so many
solutions showing it. Forecast soundings show a rather deep
dendritic growth zone for much of this event coincident with a
period of strong vertical motion, which will make for efficient
snowfall during the day into early Sunday evening. With southeast
flow in place, will have to watch for possible lake enhancement
along the Lake Huron shoreline, including eastern Chippewa County
(particularly Drummond Island). This will depend on exactly how the
wind orientation pans out, though.

The low will drag a cold front across northern Lower as it moves
from over northern Lake Michigan late Sunday evening to northeast
Lake Huron by 12Z Monday. A mid level shortwave will also cross the
region overnight. Expect the bulk of the snow to quickly diminish
behind these features, but in their wake, WNW flow off Lake Michigan
will allow for some lake effect to kick in again early Monday

Snow ratios for this event will range from around 19:1 across
eastern Upper to around 14:1 in our south, so the snow will be a
little less fluffy than recent lake effect. Winds will not be too
strong away from the lakes, so blowing snow is not expected to be an
issue. But due to the snow totals, have gone with a Winter Weather
Advisory for the entire CWA Sunday morning through Sunday night.
Current forecast yields around 3-6 inches across most of the CWA,
but higher totals approaching 7 inches will be possible across our
far southeastern counties.


Monday through Tuesday...

...Arctic air poised to move into Northern Michigan...

High impact weather potential: Lake enhanced southwest flow snow
possible Monday night.  Burst of snow and gusty winds possible with
arctic boundary late Monday night into Tuesday morning.

Pattern Synopsis/Forecast: Lingering west-northwest flow lake effect
Monday morning behind departing shortwave. Still a bit of moisture
through the favorable dendritic growth zone briefly, so another
fluffy inch possible in favorable lake effect areas.  Moisture depth
decreases quickly during the afternoon and inversions fall, as winds
gradually back to the southwest.  So would expect any remaining lake
effect snow shower activity to shift northward toward the Tip of the
Mitt and the Straits.   Upper pattern begins to transition toward a
more amplified and significantly colder regime Monday night into
Tuesday as core of cold air drops southward to the west of Hudson
Bay, allowing a surge of extremely cold air to push into the Great

Low level flow continues to back toward the southwest Monday night
in advance of the arctic boundary.  Probably not much in the way of
lake effect through the evening hours with limited moisture through
the column.  Although moisture profiles are not that impressive,
deeper moisture (850-500mb) increases overnight as arctic front
approaches, with southwest enhanced snows increasing along the Lake
Michigan coast into parts of eastern upper.  This could produce some
minor accumulations in these areas.   This activity swings inland
Tuesday morning with low level convergence axis and relatively
narrow band of deeper moisture with fropa, weakening as it pushes
toward I-75.  Although any snow amounts during this time look
minimal, winds will be gusty from the at 15 to 30 mph which will
create blowing snow/reduced visibility issues for a time. Subsidence
and limited moisture after fropa Tuesday afternoon, which will
initially limit the lake effect intensity.  Temperatures will fall
rapidly behind front throughout the day, helping to produce
below zero wind chill readings by the afternoon hours.



.LONG TERM...(Tuesday night through Saturday)
Issued at 327 PM EST Sat Dec 10 2016

I don`t think it`s ever going to stop snowing...ever. OK, well that
may be a bit of an overreach, but we are certainly going to lock
into the northern Michigan snowglobe pattern. Timing will have to be
watched the closer we get, but we will cycle between arctic wave
generated system snow, with periods of lake effect snow in between.
That said, the real story in the extended is going to be the coldest
air of the season thus far. There will be days in the offing that
will struggle to warm out of the single digits.  The pendulum has
swung the other way indeed.  Welcome home Old Man winter, we missed


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 607 AM EST Sat Dec 10 2016

Lake effect snow showers will continue to impact far Northern and
NW Lower Michigan thru Sunday morning. Focus of heaviest snow
bands will slowly shift toward the Straits (PLN) as low level
winds shift to the west and eventually to the SW ahead of low
pressure developing in the Central Plains. Intensity of lake
effect snow will diminish as high pressure builds into the region
this afternoon and evening...but will likely ramp up again late
tonight and Sunday as increasing synoptic moisture serves to
enhance SW flow lake effect snow showers.


Issued at 327 PM EST Sat Dec 10 2016

Winds will back southerly tonight, decreasing in speed in
the process. Winds further back to southeast and once again become a
touch gusty Sunday as low pressure advances into the area. Could see
some SCA conditions on some nearshore waters as quickly as Sunday
morning. More persistent gusty winds arrive through the middle
portion of the week as a surge of Arctic air drops overhead.


MI...WINTER WEATHER ADVISORY from 7 AM Sunday to 7 AM EST Monday for


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