Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 050452
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1152 PM EST Mon Dec 4 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 211 PM EST MON DEC 4 2017

Upper air pattern consists of a 500 mb trough moving into the plains
this morning with a strong shortwave in western Nebraska. This
strong shortwave becomes negatively tilted tonight as it moves into
the upper Great Lakes before forming a closed low between James Bay
and Lake Superior 00z Wed. Cold air will be coming in tonight and
there will be a rapid transition from rain to snow with this which
is already handled in the forecast. Going forecast has things well
in hand and did not make too many changes to the going forecast as
changes will be happening quickly overnight for dropping
temperatures and rain to snow will occur rapidly as well.
Temperatures will be falling on Tuesday. Winds look to be slightly
weaker with this forecast, but they stay up longer as well. Will
keep headlines going with little change.

.LONG TERM...(Tuesday night through Monday)
Issued at 332 PM EST MON DEC 4 2017

As a highly amplified ridge/trough pattern remains anchored across
the CONUS into next week, we will see persistent cold air advection
keeping temperatures below normal for this time of year. This
lingering cold air will allow the highly advertised lake effect snow
to linger across the snow belts through the middle/end of the week.
As a clipper system digs south across the region towards the end of
the week/early this weekend we should see chance for snow increase
across the entire U.P., along with lake enhancement in the north
wind snow belts.

Tuesday night through Wednesday: Overall, things look to be a bit
slower and delayed. As a result, lakeshore flooding across the west
half of the Keweenaw is expected to linger into Wednesday morning.
Also, it looks like the lake effect snow showers will linger a bit
longer in the west wind snow belts Tuesday night before gradually
transitioning over to the northwest wind belts by Wednesday
afternoon. Forecast soundings are showing ample depth and lift
through the DGZ, with an isothermal later around -18 to -20C across
the west. Therefore, while snow should be very fluffy expect
snowfall to be very efficient at times. The combination of lingering
breezy winds and falling snow be result in lower visibilities at
times. Did opt to issue a winter weather advisory for Ontonagon and
Gogebic counties; however, this time period will need to be
monitored closely for potential upgrades to a winter storm warning
if expected snow accumulations further increase than what is currently
reflected in the forecast. As the lake effect snow transitions to
the northwest wind snow belts through Wednesday, expect snow showers
to make it onshore east of Marquette and then across the higher
terrain across the north central. Accumulating and blowing snow east
of Marquette on Wednesday afternoon may require the issuance of a
winter weather advisory as we get closer.

Wednesday night through Friday: Increasing subsidence and height
rises as we get on the back side of the vigorous upper-level trough
should allow lingering lake effect snow to weaken, if not diminish in
some locations across the northwest wind snow belts by Thursday.
However, late Thursday night through Friday a potent shortwave
embedded within the main longwave trough will rapidly dig south
across the Upper Great Lakes. This will favor widespread chances for
snow across Upper Michigan and lake enhanced snow across the north
wind belts on Friday.

Saturday through early next week: Model solutions diverge in the
upper air pattern through early next week, so confidence is not high
in regards to the timing and potential impacts from additional snow.
However, it does look like there will be additional periods of lake
effect snow during this time period. There may be another shot for
system snow early next week as additional shortwaves are progged to
dig south across the region.
&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1152 PM EST MON DEC 4 2017

Low cigs/vsby will prevail with pcpn providing abundant low level
moisture. Rain may transition over to drizzle overnight as a dryslot
slides into the area, mainly impacting the KSAW TAF site. A cold
front moving through late tonight behind a deep low pressure system
will bring in very gusty sw to wsw winds along with a changeover
from rain to snow over the west. CMX will have very low vsby with
blsn on Tue. IWD may see lowered visibilities with any blowing snow
overnight tonight as heavier snow slides through the TAF site,
mainly through 12Z. The blowing snow may continue to cause reduced
visibility into Tuesday morning at IWD; however, snowfall intensity
will decrease during the day. KSAW should mainly stay out of any
snowfall.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 211 PM EST MON DEC 4 2017

A strong low pressure system over central Minnesota will rapidly
deepen as it moves across or near western Lake Superior tonight and
will bring storm force winds tonight into Tuesday evening. Gales
will then continue from late Tue into Wed night before diminishing.
Winds below gales are then expected through Sat.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory until 8 PM EST /7 PM CST/ Tuesday for MIZ002-004-
     005-009>014-084.

  Winter Storm Warning from 5 AM Tuesday to 5 AM EST Wednesday for
     MIZ001-003.

  Lakeshore Flood Advisory from 5 AM Tuesday to 8 AM EST Wednesday
     for MIZ001>003.

  Winter Weather Advisory from midnight Tuesday night to 6 PM CST
     Wednesday for MIZ009.

  Lakeshore Flood Advisory until 5 PM EST Tuesday for MIZ014.

  Winter Weather Advisory from 4 PM Tuesday to 7 PM EST Wednesday
     for MIZ002.

Lake Superior...
  Storm Warning from 4 AM to 11 PM EST Tuesday for LSZ266-267.

  Storm Warning until 11 PM EST /10 PM CST/ Tuesday for LSZ240>248-
     263>265.

  Gale Warning until 8 AM EST Wednesday for LSZ249>251.

  Storm Warning until 9 PM EST /8 PM CST/ Tuesday for LSZ162.

Lake Michigan...
  Gale Warning until 7 AM EST Wednesday for LMZ221-248-250.

&&

$$

SHORT TERM...07
LONG TERM...Ritzman
AVIATION...KEC
MARINE...07



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