Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 172035

Area Forecast Discussion
National Weather Service Marquette MI
335 PM EST Fri Nov 17 2017

.SHORT TERM...(Today and tonight)
Issued at 459 AM EST FRI NOV 17 2017


Pretty complicated in terms of ptype today into tonight. Narrow band
of snow/sleet/rain moving through the central U.P. early this
morning, but won`t last long enough to cause significant impacts.

Additional precip develops and becomes widespread later this morning
through the afternoon. As a nose of warm air aloft moves in, a mix
of rain, freezing rain, sleet, and snow will all be possible through
this evening. The E-central U.P. (roughly Menominee, Delta, Alger,
and Schoolcraft Counties) will see warmer SFC temps, so less
freezing precip expected there. Tonight, as deeper moisture exits,
upslope drizzle/freezing drizzle is possible over the N-Central and
W. Snowfall accumulations of up to 2 inches will be possible through
this evening (greatest over the higher terrain of the Keweenaw), but
most locations should see under an inch. Could see some light ice
accumulations over the W this morning, then across the interior W
this afternoon, and the higher terrain of N-central and W U.P.
tonight. Could certainly see some slippery travel conditions at
times today and tonight in areas that see freezing precip, but think
that impacts will not justify an advisory so will stick with the
Special Weather Statement.

.LONG TERM...(Saturday night through Friday)
Issued at 334 PM EST FRI NOV 17 2017

Main issues in the extended will be lake effect snow potential for
northwest wind snow belts Saturday night into Sunday and again
Tuesday into Wednesday. Travel weather into Thanksgiving looks to be
fairly quiet across much of the eastern CONUS outside of some light
lake effect snow potential.

Saturday night through Sunday: As the aforementioned stronger second
wave slides into the Upper Great Lakes Saturday night, expect colder
air to slide into the Upper Peninsula. This will act to lower the
DGZ enough to take away the freezing drizzle potential and keep
precipitation in the form of lake effect snow for mainly northwest
wind favored locations. Yet another wave is progged to slide across
the area late Saturday night into Sunday morning, which will help to
increase lake effect snow coverage. 850mb temperatures are expected
drop to the -14C to -17C range through this time period, giving
delta-t values in the 19C to 22C range.  More than enough for lake
effect snow potential. Inversion heights are progged to be around
5kft to around 8kft when accounting for lake surface temperatures;
however, the sounding is lacking moisture in the 6kft to 8kft layer.
This points to mainly a light to possibly a moderate lake effect
event for this time period. The best chance of seeing the moderate
snow would be as the aforementioned waves move overhead Saturday
night into Sunday morning. Generally looks like 1 to 3 inches with
up to 5 inches possible in the northwest wind favored snow belts.
The greatest totals are expected over the higher terrain.

Sunday night through Monday night: As weak ridging slides into the
Upper Great Lakes and low pressure begins to approach form the
Northern Plains, winds will become westerly Sunday night and then
southerly for Monday into Monday night. This will effectivly push
the lake effect snow over Lake Superior before ending as warmer air
pushes in both at the surface and aloft.

Tuesday through the extended: Models are in good agreement that a
low pressure system will slide just north of Lake Superior early
Tuesday morning and into Quebec by Wednesday morning. This will drag
a cold front through the area during this time period and shift
winds to the northwest. 850mb temperatures are progged to drop into
the low to mid teens below zero, which would again be a good setup
for some lake effect snow for northwest wind favored snow belts
through at least early Wednesday afternoon. Details will have to be
ironed out as the system gets closer. At this point will stick with
a consensus of the models as this systems looks to be handled well
with the consensus. At this point, late Wednesday afternoon through
Thanksgiving looks to be fairly quiet with dry high pressure
building across much of the eastern CONUS.

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 650 AM EST FRI NOV 17 2017

Certainly a complicated forecast with regard to precipitation type.
Expect precip that is developing across the area to fall as rain,
freezing rain, snow, drizzle and freezing drizzle through the TAF
period. Today will be more rain, freezing rain, and snow, while
tonight will be more drizzle and freezing drizzle mixed with snow at
times. Expecting IFR to occasionally LIFR conditions at all sites.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 459 AM EST FRI NOV 17 2017

Gales are expected today over central and eastern Lake Superior and
a gale warning has been posted. Cold front to the south of the low
moves through tonight with winds diminishing below gales. However,
northwest winds increase to gales again late Sat into Sat night.
Winds diminish to 30 kts Sun-Mon but more gales are possible Tue
into Wed as active pattern continues.

Upper Michigan...
  Winter Weather Advisory until 9 PM EST this evening for MIZ001-

Lake Superior...
Lake Michigan...
  Gale Warning until 7 PM EST this evening for LMZ221-248-250.



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