Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 212047

Area Forecast Discussion
National Weather Service Marquette MI
347 PM 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...(Tuesday through Sunday)
Issued at 345 PM EST SUN JAN 21 2018

The main forecast concerns through the extended are the lingering
impacts from blowing/drifting snow and lingering lake
effect/enhanced snow as the main winter storm expected to impact the
region continues to track over Lake Huron and over into Canada, then
the focus transitions to another system progged to track across the
Upper Mississippi and Great Lakes region this weekend.

Tuesday: As the main system continues to exit the region, forecast
soundings show deeper moisture beginning to vacate from west to
east. Given the shallow nature of the cold air and the marginal
support for ice based on the 850mb temperatures, it certainly is in
the realm of possibilities we could see precipitation switch over to
freezing drizzle. However, with forecast soundings still showing
colder temperatures around 900mb supportive of ice, opted to leave
out mentions of freezing drizzle for now. Lingering gusty northerly
winds will likely cause area of blowing and drifting snow, along
with reduced visibilities especially across the north central where
light snow will continue. Due to the lingering impacts, upon
collaboration with the short-term forecaster the consensus was to
run the winter storm warning through Tuesday morning across the
north central to take into account these lingering impacts. By
Tuesday evening, any lingering precipitation near Lake Superior will
quickly diminish as upper-level ridging and drier air work into the
region. Temperatures during the day will only climb into the teens
and lower 20s, so the combination of colder temperatures and gusty
northerly winds will make for a blustery day as apparent
temperatures drop down into the single digits for much of the area.

Wednesday through Friday: We could see a brief return of lake effect
snow showers out west towards the middle of the work week as a weak
shortwave tracks eastward across the Great Lakes region. Otherwise
high pressure will dominate as upper-level ridging builds across the
central CONUS, ahead of another vigorous trough beginning to dig
into the western CONUS. Return flow is expected to overspread Upper
Michigan through the end of the week as the main upper-level ridge
axis shifts eastward, allowing temperatures to climb into the 30s
and 40s by Friday!

As the aforementioned longwave trough tracks across the Rockies and
central CONUS towards the end of the week, this will favor the
development of a lee cyclone. With the more pronounced lift and
850mb warm air advection aimed across the Upper Mississippi Valley,
expect the surface low to track northeast towards western Lake
Superior by late Friday night. This will favor the development of
widespread rain/snow showers late Friday night.

Next Weekend: The medium range models have been consistent with
Upper Michigan remaining on the warm side of this next system
through a good portion of the day on Saturday. Therefore, any
precipitation that lingers across the area during the day will
likely fall as rain. Saturday will be another day with above normal
temperatures for this time of year, as highs climb into the upper
30s and lower 40s.

As the main trough axis pushes across the area and cold air
advection returns on the back side of the system, expect the rain to
transition over to snow from west to east Saturday evening into
early Sunday. This will allow temperatures to rapidly transition
from the mild pre-frontal air mass to the cold post-frontal air mass
Saturday night into Sunday. Given the cold air advection behind the
system, expect lake effect snow to impact areas downwind of Lake
Superior on Sunday, along with the return of near normal

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1247 PM EST SUN JAN 21 2018

Tricky forecast for the terminals as snow melt yesterday along with
winds switching to the northeast with a frontal passage will allow
low level moisture and upslope flow to occur bringing conditions
down this forecast period with fog and/or low clouds. This is
already occurring at CMX and should develop by this evening at SAW
and possibly IWD as winds turn to the northeast there. Could be some
freezing drizzle as well. Snow with incoming winter storm should
start up at SAW by midday on Monday.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 345 PM EST SUN JAN 21 2018

Winds will increase to 25 to 30 knots tonight through early Monday
morning, and will further increase to gales of 35 to 40 knots Monday
into Tuesday. Tuesday winds will remain between 20 and 30 knots.
During the period of higher winds, expect heavy freezing spray to
develop as well. Wednesday through the day on Thursday, things will
quiet down across the lake as high pressure moves overhead and winds
remain below 20 knots. Later this week into next weekend, winds will
pick back up to around 25 to 30 knots, with gales possible towards
the end of the weekend, as another storm system tracks across the
Upper Great Lakes.

Upper Michigan...
  Winter Storm Warning from 7 AM EST /6 AM CST/ Monday to 1 AM EST
     /midnight CST/ Tuesday for MIZ002-009>012-084.

  Winter Storm Warning from 10 AM Monday to 6 AM EST Tuesday for

  Winter Weather Advisory from 1 PM Monday to 6 AM EST Tuesday for

  Winter Storm Warning from 10 AM Monday to 1 PM EST Tuesday for

Lake Superior...
  Heavy Freezing Spray Warning from 4 AM to 6 PM EST Tuesday for

  Gale Warning from 5 PM Monday to 10 AM EST Tuesday for

  Heavy Freezing Spray Warning from 10 PM Monday to 4 PM EST
     Tuesday for LSZ263-264.

  Gale Warning from 10 AM EST /9 AM CST/ Monday to 5 AM EST /4 AM
     CST/ Tuesday for LSZ162-263.

Lake Michigan...
  Gale Warning from 10 AM Monday to 4 AM EST Tuesday for LMZ248-



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