Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 192348

Area Forecast Discussion
National Weather Service Marquette MI
648 PM EST Sun Nov 19 2017

.SHORT TERM...(This evening through Monday)
Issued at 324 PM EST SUN NOV 19 2017

The main forecast concerns through the short-term forecast is the
potential for continued mainly light lake effect snow for west to
west-northwest wind favored snow belts through late this evening.

Tonight: A surface high pressure system to the south of the area
will shift very slowly to the east through the overnight hours. The
main impact this will have on the U.P. weather will be to shift the
winds to the west-northwest or west through late evening then to the
southwest overnight. This will effectively shift the lake effect
snow to the Keweenaw Peninsula and over the far eastern U.P., closer
to the shoreline east of Munising through the evening hours.
Overnight, the lake effect snow will shift over Lake Superior and
slowly diminish as drier air moves into the area. To start the
evening, 850mb temperatures are progged to be around -10C to -12C;
however, as winds become southerly and WAA increases across the
area, 850mb temperatures are expected to warm to around -6C to -8C
by 06Z/09Z Monday. This along with drier air moving into the area,
would all point to the diminishing lake effect snow trend tonight.
An addition 2 to 4 inches can be expected closer to the shoreline
over the eastern U.P. In fact, a mesolow over north-central Lake
Superior will potentially help support the higher end of these
totals over easter Alger County and northern Luce County. The
mesolow will likely have some gustier winds with it during the
evening hours; therefore, issued a SPS for lower visibility and
heavier snowfall rates. The Keweenaw Peninsula may see up to an
inch; however, the drier air and decreasing inversion heights will
help to limit totals.

Monday: As the aforementioned high pressure system slides to the
east, south winds will increase, allowing for more WAA into the
area. Temperatures aloft will steadily warm and the lake effect snow
potential will be gone by early Monday morning for all of the U.P.
Many areas may actually see some sunshine sneaking out by Monday
afternoon as drier air continues to filter into the U.P. Also, with
the warm air advection, temperatures are expected to warmer, with
highs reaching into the upper 30s to around 40 degrees in most

.LONG TERM...(Monday night through Sunday)
Issued at 346 PM EST SUN NOV 19 2017

A compact trough digging SE across southern Canada will bring a
987hPa surface low just north of Lake Superior late Monday night.
Increasing cold air advection and a strengthening pressure gradient
will produce blustery conditions across the CWA late Monday night
through the day Tuesday. NW wind gusts to 40mph along Lake Superior
and to 30mph inland will be possible.

Moderate lake effect snow is also expected Monday night through
Tuesday night for the NW-wind snow belts, especially east Tuesday
afternoon as inversion heights rise to around 8kft. Winter Weather
Advisories may be needed across the east Tuesday afternoon and

Little weather impacts are expected for any holiday travel on
Wednesday as backing surface winds and WAA limit precip to light LES
across the Keweenaw and far NE Wednesday and Wednesday night.
Another quick shot of cold air will allow for an increase in LES for
the NW-wind snow belts Thanksgiving afternoon and evening before WAA
and backing flow end LES by late Thursday night.

A more potent clipper system passing north of Lake Superior is then
expected to affect the Upper Great Lakes Friday night through
Saturday. The system will be rather progressive, but a more southern
track would produce decent impacts to the CWA via snow and wind.

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 648 PM EST SUN NOV 19 2017

Backing winds to the sw and s along with warming air mass will bring
an end to ocnl lake effect -shsn at KCMX tonight with MVFR cigs
clearing out to VFR late in the night. At KIWD/KSAW, VFR conditions
will prevail thru the fcst period under drier air mass associated
with passing high pres ridge.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 324 PM EST SUN NOV 19 2017

West to west-northwest winds of 20 to 30 knots are expected through
this evening as pressure gradient remains fairly tight ahead of high
pressures building into the area. An area of low pressure will
approach, then move through the area Monday night through Tuesday
giving a period of south gales Monday night before shifting to
northwest gales Tuesday into Tuesday night. The next chance of
seeing near-gale winds will be Friday into Saturday; otherwise,
winds are generally expected to be in the 15 to 25 knot range.

Upper Michigan...
Lake Superior...
  Gale Watch from Tuesday morning through Tuesday evening for

  Gale Watch from Tuesday morning through Tuesday evening for

  Gale Watch from Monday evening through Tuesday afternoon for

Lake Michigan...
  Gale Watch from Monday evening through late Monday night for



LONG TERM...Kluber
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