Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 071154

Area Forecast Discussion
National Weather Service Marquette MI
654 AM EST Wed Dec 7 2016

.SHORT TERM...(Today and tonight)
Issued at 455 AM EST WED DEC 7 2016

Mid-level low is currently NW of Lake Superior, and the SFC low is
just NE of there with a trough extending SW through the MN
arrowhead. Given cyclonic SW winds and 850mb temps of -12C over the
area, it only makes sense that there are intensifying LES bands over
the western lake and some hints of such can be seen from the DLH
radar. These bands should continue to intensify, especially as the
trough moves into the western lake. The expectation is that the
bands will push into the Keweenaw this morning as the low pressure
system and SFC trough move east. Exact timing and extend of the
bands moving into the Keweenaw is not completely certain, but have
gone with a solution that is favored by almost all models that gives
warning level snowfall amounts to the NW Keweenaw today.
Therefore, the advisory was upgraded to a warning. As the trough
continues to settle south across the area this evening and tonight,
a burst of heavy snow will accompany that trough and be the
beginning of NW wind LES that will continue through late-week.
Upgraded the other watches to warnings and added Luce and Northern
Schoolcraft to the advisories. Have total accumulations through
tonight of 3-14" from Ironwood to Copper Harbor (highest over the
Keweenaw due to the SW flow band expected today). Elsewhere near
Lake Superior, have 1-3" tonight. Of course, additional significant
accumulations occur in the long term time range.

.LONG TERM...(Thursday through Tuesday)
Issued at 300 AM EST WED DEC 7 2016

Nam shows a 500 mb trough over the upper Great Lakes 12z Thu.
Troughing remains through 12z Sat over the area. Prolonged lake
effect scenario in NNW lake effect snow belts will continue this
forecast period. This was covered in the previous forecast and used
that as the basis for this forecast. Will have numerous advisories
up for the NNW lake effect snow belts continuing. Did not make too
many changes to the going temperatures. Snow ratios look to be
between 20 to 25 to 1 for this event.

In the extended, GFS and ECMWF show a zonal 500 mb pattern across
most of the U.S. with a broad trough across most of the country 12z
Sat. 850 mb temperatures across Lake Superior at 12z Sat are from -
17C to -19C. A shortwave digs into the upper Great Lakes 12z Sun.
Troughing continues over the area Mon into Tue with cold air
remaining over the area through then. Temperatures will continue to
be below normal and lake effect snow showers will continue through
this forecast period as well. Get system snow in for Sat night
through Sun morning and then lake effect gets going in earnest again
Sun night through Wed with even colder air arriving in. The lake
effect event will be in WNW lake effect snow belts. Could see some
below zero temperatures for lows Tue night and Wed night.

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 653 AM EST WED DEC 7 2016

A trough will bring a band of lake effect snow into KCMX today,
although the exact timing remains uncertain. Conditions will
probably be reduced below what is in the forecast when this band
moves through KCMX, but was not confident enough in timing and
extent at this point to include such details. NW winds will kick in
behind this trough at KCMX and KIWD this evening and tonight, with
moderate to heavy lake effect snow expected. The trough is expected
to reach KSAW around or after 12Z tomorrow, bringing snow along and
behind it.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 455 AM EST WED DEC 7 2016

Southwest gales of 35-40kt will occur across mainly the southern
half of Lake Superior today. Winds will shift northwest this evening
and tonight and with much colder air sliding across Lake Superior
from Canada. This coupled with winds mainly between 25-30kt and
occasional gales to 35 kt will allow waves to easily build later in
the week.

Upper Michigan...
  Lake Effect Snow Advisory from 1 AM Thursday to 7 AM EST
     Saturday for MIZ006-007-084-085.

  Lake Effect Snow Warning until 7 AM EST Saturday for MIZ001-003.

  Lake Effect Snow Warning from 10 PM EST /9 PM CST/ this evening
     to 7 AM EST /6 AM CST/ Saturday for MIZ002-009.

  Lake Effect Snow Warning from 1 AM Thursday to 7 PM EST Friday
     for MIZ004-005.

Lake Superior...
  Gale Warning until 1 AM EST Thursday for LSZ265-266.

  Gale Warning until 7 PM EST /6 PM CST/ this evening for LSZ162-

Lake Michigan...


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