Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 210829

Area Forecast Discussion
National Weather Service Marquette MI
329 AM EST Sun Jan 21 2018

.SHORT TERM...(Today and tonight)
Issued at 327 AM EST SUN JAN 21 2018

Today: Main focus will be on cold front settling southward from
Ontario and northern Lake Superior toward northern Upper Michigan in
the afternoon and evening. Expect developing east to northeast winds
in wake of the front which will result in upslope lift from the
Keweenaw to north central higher terrain. A lot of low clouds
already behind the front early this morning over northern Ontario
and expect these clouds to spread into Upper Mi late this afternoon
and evening aided by additional moisture off Lk Superior. Could even
be enough low-level moisture and lift for drizzle or freezing
drizzle so will continue slight chances for the Keweenaw into
Marquette-Baraga counties. Kept in slight chances this morning for
the far south central cwa in case weakening fgen band lingers a bit
longer to produce some light snow. Expect any patchy fog this
morning to be shallow and should lift a few hours after sunrise with
weak heating/mixing.

Both the low clouds and increasing high clouds ahead of developing
winter storm will result in cooler temps than last couple days.
Readings will be in the lower to mid 30s coolest north.

Tonight: Models continue to indicate delayed arrival of pcpn ahead
of system approaching from the Central Plains due to drier e-ne flow
off Ontario circulating around sfc high centered over the southern
tip of James Bay. Prior to the onset of system snow moving into
south central Upper Mi late tonight, easterly flow will back
northeasterly resulting in continued upslope flow across the north
central Upper Mi. Forecast soundings pick up on this upslope flow,
including deepening of shallow moisture to near 3 kft by midnight
Mon morning. Will continue mention of upslope fzdz over north
central counties (Baraga and Marquette) into Sunday evening with
snow mixing in with freezing drizzle after midnight due to seeder-
feeder mechanisms from lowering mid cloud deck.

.LONG TERM...(Sunday night through Saturday)
Issued at 422 PM EST SAT JAN 20 2018

...Winter Storm to Impact Upper Michigan Monday into Tuesday...

The main forecast concern remains the approaching winter storm
Monday into Tuesday, where a swath of heavy, wet system snow is
expected to lift across portions of Upper Michigan. A Winter Storm
Watch has been issued for portions of western and much of central
Upper Michigan in advance of this approaching system.

Sunday night through Tuesday: The overall trend among the medium-
range models is to continue to slow the arrival of the system
expected to lift across the Upper Great Lakes during this time
period. In fact, the tail-end of high-res guidance suggests that the
timing may need to be pushed back even further then what is
currently reflected within the forecast. Prior to the onset of
system snow, easterly flow will back northeasterly and begin to
enhance localized upslope flow across the north central Sunday night
into early/mid Monday morning. Forecast soundings pick up on this
upslope flow nicely, including deepening of this shallow moisture
through early/mid Monday. Given the delay in the deeper moisture,
have included mentions of freezing drizzle across these upslope
areas in the north central Sunday night into mid/late Monday
morning. This may result in a glaze of ice, but we could also see
snow mix in with this freezing drizzle as we could see impacts on
precipitation type due to the seeder-feeder process.

The main axis of wet, heavy system snow is expected to track across
portions of Upper Michigan mid-Monday morning through early/mid
Tuesday morning, which will bring travel impacts as SLRs will lower
to around 10-15:1. Given the track of the surface and 850mb low
confidence is highest based on current guidance that the heaviest
snow will track across central portions of Upper Michigan,
especially the higher terrain in the north central where upslope
northeasterly flow will provide localized lift to enhance snowfall
amounts. However, any slight shift in the storm track may result in
this axis of heavy snow shifting a bit west or east, as well as
having impacts on precipitation type.

As the main system continues to exit the region on Tuesday,
depending on how cold 850mb temperatures get lingering lake effect
snow will be possible across the north wind snow belts. Also,
lingering gusty northerly winds may lead to blowing snow concerns,
especially near Lake Superior.

Wednesday through Friday: We could see lingering lake effect snow
near Lake Superior Wednesday into Thursday, but as surface ridging
slides across the Upper Great Lakes the 850mb winds become rather
disorganized. Therefore, not expecting much in the way of
accumulating lake effect snow during this time period. Through
Friday, we will see ridging build across the central CONUS and moves
across the Great Lakes region. The resulting warm air advection will
push temperatures into the upper 30s and lower 40s by Friday.

Next Weekend: The above mentioned warm air advection will continue
to lift northeast across the Upper Great Lakes and allow the return
of widespread precipitation out ahead of the next system progged to
track across the Upper Mississippi Valley. Based on the current
model guidance, we will initially be on the warm side of this next
surface low, so we may see rain and snow spread across Upper

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1133 PM EST SAT JAN 20 2018

Tricky forecast for the terminals as snow melt yesterday along with
winds switching to the northeast will allow low level moisture and
upslope flow to occur and will bring conditions down this forecast
period with fog and/or low clouds. Will continue pessimistic with
this issuance even with mid and high level clouds around overnight.
As a cold front on the north end of Lake Superior settles across Lk
Superior and northern Upper Michigan Sunday aftn, expect developing
east to northeast winds to result in upslope low stratus at CMX and
SAW by late Sunday aftn into Sunday evening. May be some freezing
drizzle as well, especially at CMX. CMX will have the worst
conditions at VLIFR by Sun morning.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 327 AM EST SUN JAN 21 2018

Strongest winds on Lake Superior during this fcst period will occur
Monday into Tuesday as low pressure tracks from the Central Plains
across northern Lower MI into southern Quebec. NE to N gales are
expected over most of Lk Superior during that time so will continue
the posted gale watch. Heavy freezing spray will also develop late
Monday night through Tuesday.

Upper Michigan...
  Winter Storm Watch from Monday morning through late Monday night
     for MIZ002-009>012.

  Winter Storm Watch from Monday afternoon through Tuesday
     afternoon for MIZ004-005-013-084.

Lake Superior...
  Gale Watch from Monday evening through Tuesday afternoon for

  Gale Watch from Monday morning through Tuesday morning for

Lake Michigan...
  Gale Watch from Monday morning through Monday evening for LMZ248-



LONG TERM...Ritzman
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