Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 180444

Area Forecast Discussion
National Weather Service Gaylord MI
1144 PM EST Wed Jan 17 2018

Issued at 952 PM EST Wed Jan 17 2018

Larger patch of high clouds continues to thin as it crosses the
Saginaw Bay area. A few thin filaments of high clouds are found in
eastern upper MI. Skies are otherwise clear this evening. Some
low clouds are seen over the east half of Superior, and this is
making some slow progress toward the eastern UP. However,
1000-850mb winds will start to back slightly after 06z, so don`t
see that cloud mass engulfing the entire forecast area.

That said, near-term guidance continues to highlight low cloud
development over northern MI after 07-08Z or so. This occurs as
inversion heights fall with warm advection aloft. However, models
are not totally on board with this though, and consensus hi-rez
near-term guidance suggests backing off somewhat. Will do so.

Tight pressure gradient is maintaining a gusty w to sw surface
winds, keeping temps from falling too far despite clear skies. If
we don`t cloud up appreciably, there may be window late tonight
as the pressure gradient relaxes somewhat, allowing temps to drop
off. Will cautiously tweak min temps downward.


.NEAR TERM...(Tonight through Thursday)
Issued at 337 PM EST Wed Jan 17 2018

...Minor weather concerns over the next few days...

High Impact Weather Potential...none.

Pattern Synopsis/Forecast...Subtle short wave ridging continues
to build into the western Great Lakes this afternoon. Surface high
pressure has drifted into the lower Mississippi River Valley with
low pressure over the southern Hudson Bay region. In between
these two systems...pocket of warmer low-mid level air continues
to wedge into the western Great Lakes along with a batch of warm
advection forced enhanced cloud cover rolling through the region.
Earlier radar returns and spotty -SN has ended and mid/high cloud
cover has been gradually thinning from the NW...although cloud
cover has apparently become "stuck" into some semblance of a
standing wave across upper and northern lower Michigan. That
is...clouds keep regenerating "in place" within the NW flow
aloft. Lastly...gusty W/SW surface winds continue across northern
Michigan with some blowing snow evident on area webcams and
surface obs (MCD is reporting 1 3/4SM HZ this last hour)

I still anticipate mid and high level cloud cover will thin out
over the next few hours leaving mainly clear skies for a good part
of the evening. After that...there remains a fair amount of
uncertainty over cloud trends overnight into Thursday. Warm
advection persists with a strong inversion developing above 925
MB or so and shallow cold air remaining down to the surface. Just
about all guidance low level RH forecasts remain bullish in
developing stratus across northern Michigan later overnight and
persisting through Thursday as we begin to advect higher dewpoint
air into the region. Stratus development might also get some help
from the lakes as temps at the base of the inversion remain cold
enough for heat/moisture flux off the lake surface. If it happens...
lake induced flurries/freezing drizzle are also not out of the
question...although per forecast soundings...low level saturated
layer depth stays a bit on the shallow side.

Meanwhile upstream...compact short wave over southern
Saskatchewan this afternoon will slide across northern Michigan
during Thursday afternoon. A moisture starved wave. But...bump in
larger scale forcing and introduction of some better moisture
aloft might just be enough to squeeze out some light snow/flurries
especially if we do get that lower cloud layer (via seeder/
feeder processes).


.SHORT TERM...(Thursday night through Saturday)
Issued at 337 PM EST Wed Jan 17 2018

...Mild Temperatures...

High Impact Weather Potential: Minimal.

Pattern Forecast: Well defined but moisture starved system exits
east of the area Thursday evening.  Little in the way of surface
reflection with this system and any precipitation should be quite
light/scattered.  Rising heights and high pressure for the end of
the week into the beginning of the weekend with warmer temperatures.

Primary Forecast Concerns/Challenges: Small threat for a few snow
showers or a touch of freezing drizzle early Thursday evening.
Another challenge will be high temperatures for Friday and Saturday
given increasing warm air advection.

Little in the way of sensible weather is expected through the
forecast period, with the one exception revolving around the early
Thursday evening time frame as a moisture starved wave slides
through the northern Great Lakes.  There may be a brief window when
moisture becomes marginally deep enough for some scattered snow
shower activity, but forecast soundings show conditions not
conducive to widespread precipitation.  There could even be a bit of
freezing drizzle as mid level moisture diminishes. Overall, not
looking like much precipitation and any impacts should be minimal.
Generally dry conditions Friday into Saturday with rising heights
and warming temperatures.  The southern end of a shortwave trough
will skirt across eastern upper Michigan Friday afternoon, possibly
producing a few rain or snow showers(little sleet?). This system
will help to tighten the pressure gradient across the area heading
into Friday night, likely resulting in a period of gusty southwest
winds. Moderating temperatures throughout this period, with high
temperatures of 40+ degrees in many areas by Saturday.

.LONG TERM...(Saturday night through Wednesday)
Issued at 337 PM EST Wed Jan 17 2018

High impact weather potential: Watching potential storm Sunday
night into early next week. Plenty of uncertainty with this
system, including eventual track and p-type.

Primary focus through the extended period continues to revolve
around the late weekend - early next week time frame as guidance
remains consistent with the idea of a wave ejecting out of the Four-
Corners region with cyclogenesis lee of the Rockies by Sunday
morning. This wave and strengthening area of low pressure is
expected to trek northeastward toward the western Great Lakes late
Sunday into Monday. Confidence is growing in the track of this
system...but is still low in handling the details of p-type.
One area of concern with this system is the position of a 1035mb
area of high pressure south of Hudson Bay, which may act to keep low
level winds more e/se as temperatures aloft warm - possibly
resulting in greater icing potential for the northern 1/2 of the
area. Definitely a system worth monitoring over the next several
days. Will continue to highlight storm in the HWO and weather story
graphic. Colder air (briefly) works back into the northern Great
Lakes Tuesday into Wednesday behind departing low pressure system,
with a period of lake effect snow possible.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1144 PM EST Wed Jan 17 2018

Some thin cirrus over northern MI presently, while some lower
stratocu edges toward eastern upper MI from Superior. Most
guidance continues to indicate a low cloud deck (MVFR) developing
over northern lower MI overnight into Thursday, though the models
are becoming less aggressive in doing so. Have slowed the expected
clouds down somewhat, but otherwise taking a `wait and see`

Gusty w/sw surface winds will decrease overnight and Thursday, as
the pressure gradient between low pressure to the north and high
pressure to the south weakens. LLWS continues overnight.




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