Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 021753

Area Forecast Discussion
National Weather Service Marquette MI
1253 PM EST Fri Dec 2 2016

.SHORT TERM...(Today and tonight)
Issued at 444 AM EST FRI DEC 2 2016

Today and Tonight: The surface low and upper-level low that has be
slowly moving across the Upper Great Lakes over the past few days is
continues to slowly depart the area across southern Quebec today and
into the New England states tonight. As this happens, the low will
keep a surface trough extending westward across the U.P. The
presence of this trough along with 850mb temperatures in the -6C to -
10C range across much of the U.P. through this time period will give
continued chances of lake effect snow for the northwest to west
northwest wind favored locations. Overall moisture is not
particularly deep anywhere across the U.P., which will help to limit
the total snowfall accumulations. At this point, the main focus for
accumulation would be across the east through this time period as
the increased fetch helps to moisten the sounding and that area will
be closer to the pieces of energy wrapping through the area.
The western portions of the U.P., from the Keweenaw down to Ironwood
may see some scattered snow showers this morning, but the deeper
moisture slides out fairly quickly so it is possible that the precip
today may be more of a light drizzle to freezing drizzle mix with an
occasional snow shower mixed in. Again, due to the shallow moisture
out west, the probability for ice in the clouds is greatly reduced.
As the aforementioned small wave of energy works through the area
early this evening through tonight, the precipitation may transition
back to more snow over the Keweenaw as slightly deeper moisture
slides across the area. At this point the increased moisture and
energy is expected to remain over then northeast half of the U.P.,
which would keep drizzle and a few scattered snow showers southwest
of the Keweenaw, mainly in the higher terrain, with mainly snow
showers expected for areas east of Marquette and over the Keweenaw
Peninsula. In the areas where freezing drizzle does occur, roads
could become fairly slippery, especially early in the morning and at
night. This will especially be the case for untreated roads. Highs
today will be in the 30s with overnight lows mainly in the mid 20s
to low 30s.

.LONG TERM...(Saturday through Thursday)
Issued at 324 AM EST FRI DEC 2 2016

Upper air pattern 12z Sat will consist of a closed 500 mb low over
northern Mexico with a shortwave in the northern plains. The trough
in the northern plains moves into the upper Great Lakes on Sun. Nam
shows some deeper moisture and 850-500 mb q-vector convergence
moving through the area on Sun before both move out Sun night.
Basically, did not make too many changes to the going forecast
with chance pops for sun into sun night.

In the extended, GFS and ECMWF show a closed 500 mb low over TX and
a trough in the northern Rockies 12z Mon. This closed low over TX
moves northeast and opens up while the trough over the Rockies heads
east into the northern plains 12z Tue. This trough amplifies over
the central U.S. mid week. The trough moves into the upper Great
Lakes on Thu along with colder air aloft. Temperatures will fall
below normal starting Thu. Still looks like there could be a big
storm Wed night into Thu, but confidence is still low with the
details right now.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1252 PM EST FRI DEC 2 2016

Generally will keep with persistence forecast at the TAFs into Sat.
Expect MVFR cigs and MVFR vsby. Light snow flurries may give way to
drizzle/freezing drizzle rest of this aftn into early evening at IWD
or CMX. Will keep it snow for now as confidence in seeing drizzle as
primary ptype is low. Better chance of steadier light snow will
return later in the evening and will persist through rest of the TAF
period. As the snow moves in, vsby could drop to IFR at times late
tonight into Sat. especially at CMX, but for the most part should
stay MVFR.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 444 AM EST FRI DEC 2 2016

Surface low continues to drift east away from Lake Superior but
tighter pressure gradient continues to linger across Lake Superior,
keeping northwest winds 20 to 30 kts through today, strongest over
the east half. High pressure moving in from the Plains will diminish
the winds to 20 kts or less tonight into the weekend. An approaching
low pressure trough on Wednesday will result in southeast winds
increasing to 25 kts, strongest over eastern sections, with
northwest gales to 35 knots a possibility for Thursday across much
of Lake Superior.

Upper Michigan...
Lake Superior...
Lake Michigan...


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