Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231933

Area Forecast Discussion
National Weather Service Marquette MI
233 PM EST Mon Jan 23 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 232 PM EST MON JAN 23 2017

Broad upper trough from western Canada to the Upper Great Lakes
becomes more influenced by deepening trough from western Conus to
the central Plains through Tue. At the sfc, weak trough from
Manitoba to the Great Lakes dissipates as strong low pressure system
emerges over the central Plains and noreaster low pressure system
continues its trek along the coast of the Mid Atlantic and New
England states. Weak pressure pattern tonight through Tue will keep
light winds and moisture in place from higher dwpnts and melting
snow and that spells more areas of dense fog.

Within the broad trough aloft, shortwave lifting northeast across
Upper Great Lakes combined with increasing deeper moisture above h9
and up to h7-h6 should bring an area of steadier precipitation over
far eastern cwa (likely pops only over Luce county with only small
chances farther west of that area) mainly this evening. Soundings
show it will be close call whether saturation occurs high enough to
bring ice crystals into play. If ice crystals are introduced then
could see snow mix in with the rain. Otherwise, just looking at
rain/drizzle with no snow. Will continue with mix of rain/snow over
far east but otherwise will just have drizzle or freezing drizzle
based on low level temps. Seems better chance of drizzle would be
over east closer to the deeper moisture and also late tonight into
Tue morning over the western higher terrain where NW winds provide
upslope lift. Soundings show some weak lift in low-level moist layer
over west so that would also support possible drizzle. Joined WFO
GRB and increased temps slightly so now have most areas staying just
above freezing into the mid 30s tonight. Therefore not expecting
much icing even as temps are in the lower 30s.

Later Tue morning into the aftn the shortwave and deeper moisture
gradually depart leaving mainly drizzle if anything with best
chances over far east. Kept some fog going especially during the
morning when low-level saturation will be maximized. Central plains
system will continue to organize on Tue aftn but expect stronger
forcing and deeper moisture from that system will not arrive until
after 00z Wed.

.LONG TERM...(Tuesday through Sunday)
Issued at 446 AM EST MON JAN 23 2017

Main stories in the long term are mid-week snow and colder air that
will bring the return of LES.

A shortwave will move south of the area Tue night and Wed, which
will bring snow to portions or all of the CWA. Exact track remains
uncertain, as a couple models are taking it farther south which
would mean parts or even much of the area would be dry (or possible
some drizzle/freezing drizzle). Current thinking is that 2-4 inches
of snow will fall 00Z Wed to 00Z Thu, with potential for higher and
lower amounts depending on track.

Major pattern change starts mid-week as the upper trough shifts E
across the country, settling over the eastern half of the CONUS by
the weekend. Colder air will promote LES in N-NW wind snowbelts
during this time, but potential for moderate to heavy LES will not
exist until the colder air (850mb temps down to -18C) move in. LES
may end on Mon as winds turn SW ahead of a potential low pressure

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 105 PM EST MON JAN 23 2017

With lingering low level moisture over slowly melting snow pack and
light winds, expect some dense fog with LIFR to VLIFR conditions to
continue into Tuesday. Though vsby may try to improve up to 1SM
briefly this aftn the vsby should fall back toward airport mins
tonight especially at IWD and CMX. Similar to last two days have
seen better vsby at SAW, but cigs remain low. Expect the vsby to
drop at SAW tonight with even slight cooling.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 232 PM EST MON JAN 23 2017

A relatively weak pressure gradient over the Upper Great Lakes in
the absence of any strong weather systems will continue to result in
winds under 20 kts over Lake Superior early this week. As a low
pressure system moves from the central Plains to eastern Canada mid
to late week expect NE winds to 25 kts Tue night then N-NW winds to
25 kts Wed into Fri.

Upper Michigan...
Lake Superior...
Lake Michigan...
  Dense Fog Advisory until 10 AM EST Tuesday for LMZ248-250.



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