Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 162038
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
338 PM EST Sat Dec 16 2017

.SHORT TERM...(Today and tonight)
Issued at 408 AM EST SAT DEC 16 2017

Moderate LES into Alger County will gradually weaken while shifting
W this morning, with 2-4" of additional snow in Alger County through
today. Once the snow shifts W, areas of Marquette County near Lake
Superior will be favored for light to briefly moderate LES through
the morning hours with 1-2" (maybe up to 3") of accumulation. Given
high snow to liquid ratios and weak winds, do not expect significant
impacts. Cancelled the Advisory for Marquette County since the
LES band that was expected over the eastern part of the county
stayed in Alger County and no other significant impacts are
expected. Also cancelled Baraga and southern Houghton Advisories
given no significant impacts expected. The Keweenaw will be
tricky today. The winds will become E to ESE, favoring the
Keweenaw for LES, but winds will be steadily shifting and will
also be variable with height, so not really expecting anything too
significant, maybe up to another 4" today. Will let the Advisory
continue for the Keweenaw given uncertainty in how that will
evolve.

The E-SE winds may result in some light snow showers over the S-
central this afternoon and evening, possibly transitioning to very
light freezing drizzle tonight as moisture leaves the DGZ.

.LONG TERM...(Sunday night through Saturday)
Issued at 337 PM EST SAT DEC 16 2017

Monday night through Wednesday afternoon: A broad trough sweeping
across southern Canada will brush the CWA Monday night into Tuesday.
Some light snow showers will accompany this trough across mainly the
northern CWA late Monday evening into early Tuesday morning. Colder
air aloft that would be sufficient for LES will lag the main trough
axis, so more prominent LES will hold off until a secondary surface
trough crosses the west Tuesday afternoon and the east Tuesday
evening. Though LES will be generally weak early Tuesday, gusty
W/WNW winds to 45mph across mainly the Keweenaw Peninsula combined
with a loose snowpack may create intermittent whiteout conditions
Tuesday into Tuesday evening. The same will likely hold true near
Lake Superior east of Munising Tuesday afternoon and evening. A
period of moderate lake effect snow for the W to NW wind snow belts
is then expected Tuesday night before diminishing from west to east
on Wednesday.

Wednesday night through Saturday: Though there remains a lot of
uncertainty in the forecast during the second half of the week, the
main message is that more active weather with accumulating snow will
affect at least portions of the western Great Lakes Wednesday night
through Friday.

A potent mid-level trough moving onto the NW CONUS Tuesday night
will become stretched across the central CONUS by Thursday
afternoon. The extreme positive tilt with the northern portions of
this trough complicate the forecast across the Upper Great Lakes by
Wednesday night. Somewhat disorganized lee cyclogenesis in the
Plains will spread a shield of WAA precip across the region
Wednesday evening into Thursday. Guidance has been quite
inconsistent on the placement of the generally narrow swath of
precip, with the GFS switching from the northern-most solution
yesterday to a much more open southern track with today`s 12Z
guidance. The GEFS and other long-range guidance only increase
uncertainty with a wide distribution of solutions. With that said,
there is a relatively high chance of at least some accumulating snow
across the CWA with this system Wednesday night into Thursday.

By Friday and Saturday, model disagreements grow substantially, with
some solutions suggesting chances of an organized system bringing
accumulating snow across the region as the upper trough receives a
re-enforcing shot of energy from the north. Again, with significant
uncertainty this far out, those with holiday travel plans should
continue to monitor forecast updates.
&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1250 PM EST SAT DEC 16 2017

Some lingering light lake effect snow showers at KCMX will end early
this afternoon. Otherwise, VFR conditions will gradually give way to
MVFR cigs tonight as srly low level flow with increasing moisture
advection develops.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 408 AM EST SAT DEC 16 2017

Southwesterly winds will increase late Monday to 20 to 30 knots
before veering to northwesterly gales to 35-45 knots late Mon night
through Tue night. With increasing wave heights, freezing spray is
possible Tuesday night into Wednesday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 5 PM EST this afternoon for MIZ001-
     003.

Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Titus
LONG TERM...Kluber
AVIATION...JLB
MARINE...Titus



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