Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 102035

Area Forecast Discussion
National Weather Service Marquette MI
335 PM EST Sun Dec 10 2017

.SHORT TERM...(This evening through Monday)
Issued at 334 PM EST SUN DEC 10 2017

General lake effect ongoing will diminish through this evening with
winds becoming southerly ahead of clipper/SFC low. 1-2 inches of
snow are expected tonight into Mon morning with the clipper, with
the most along the WI border depending on the track of the
shortwave. Strong NW CAA will commence behind the system, leading to
NW flow LES by evening. Expect another 1-2 inches in the snowbelts
over NW Upper MI through 00Z Tue. Overall limited impacts in the
short term, with the focus more into the early long term part of
the forecast with the persistent LES.

.LONG TERM...(Monday night through Sunday)
Issued at 332 PM EST SUN DEC 10 2017

The dominant pattern of an upstream amplified ridge will persist,
and will maintain the downstream trough over the Great Lakes region
through the bulk of the extended periods. Closer to Thur/Fri,
ensembles do begin to indicate the ridge beginning to relax
marginally; however, guidance continues the theme of quick clippers
skirting the Upper Midwest/Great Lakes.

The more concerning feature in the medium term, Mon ngt-Tue ngt,
will be on a departing clipper that will bring strong winds to the
Upper Peninsula. In addition to the tight pressure gradient poised
to develop, it also appears favorable for good LES bands setting up.
With winds turning northeasterly then northerly, the most favored
areas will likely be Northeast Marquette County stretching east
through Alger County. SLRs have continued to be progged around 25:1
to possibly 30:1, with QPF totals between 0.4 to 0.6", resulting in
snowfall in excess of 8" to possibly much higher than a foot in
places by late Tue ngt. Further away from Lake Superior and snowfall
totals diminish significantly, to possibly sub-advisory conditions.
But the wildcard could be the gusty winds causing blowing-drifting
conditions and reduced visbilities in places from fresh snowfall in
prior days. Much colder temps will also accompany the back edge of
the departing shortwave, as a potent thermal trough dives into the
Great Lakes region. Temps will struggle to warm beyond the single
digits...likely warming into the low/mid teens by late Tue aftn. But
given the gusty winds, wind chill values will linger around zero to
a few degree below zero.

Tue ngt-Sat: Troughing will finally begin to lift/pivot east,
allowing mid-lvl heights to rise and create more of a
diffluent/dry flow aloft. This should diminish the coverage of LES
and any organized snow bands across the U.P. for a few periods;
however, flow will eventually turn northwesterly and help to re-
energize some snow showers later in the week. Guidance is keeping
up with a semi- active setup, with another clipper system arriving
Thur. The only wrinkle with the Wed ngt/Thur system could be a
period of strong parcel ascent along front edge, resulting in
faster moistening of the profile and development of snow showers
earlier. This could translate into yet another period of
moderate/heavy snow. Temps will continue to be sub-seasonal with
highs in the upper teens to perhaps mid 20s by late next week.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 120 PM EST SUN DEC 10 2017

Typical lake effect scenario playing out right now, but that will
gradually diminish through this evening. Synoptic snow will move in
late tonight into Mon morning, mainly impacting KIWD and possibly
KSAW. Behind that low pressure system, more lake effect kicks in
late Mon into mid-week.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 334 PM EST SUN DEC 10 2017

Tonight and Monday morning will be relatively calm with winds below
20 knots.  Winds will then increase markedly Monday afternoon and
evening with northeasterly gales to 35 knots across much of Lake
Superior and a few gusts to 40 knots across the central and eastern
zones. Combined with increasing wave heights, heavy freezing spray
is possible Monday afternoon through early Tuesday. Northwesterly
winds will then decrease Tuesday morning but stay within the 20 to
30 knot range until early Wednesday morning.  Winds will then remain
below 20 knots until Thursday and Friday, when northeasterly winds
will increase to 15 to 25 knots.

Upper Michigan...
  Winter Storm Watch from Monday afternoon through late Tuesday
     night for MIZ005-006.

Lake Superior...
  Gale Warning from 7 PM Monday to 7 AM EST Tuesday for LSZ248>251-

  Gale Warning from 4 PM EST /3 PM CST/ Monday to 1 AM EST
     /midnight CST/ Tuesday for LSZ162-240>242-263.

  Gale Warning from 4 PM Monday to 7 AM EST Tuesday for LSZ243>245-

Lake Michigan...
  Gale Warning from 7 PM Monday to 7 AM EST Tuesday for LMZ221-248-



LONG TERM...Beachler
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