Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 061111

Area Forecast Discussion
National Weather Service Marquette MI
611 AM EST Tue Dec 6 2016

.SHORT TERM...(Today and tonight)
Issued at 435 AM EST TUE DEC 6 2016

Upper air pattern consists of a closed 500 mb low over the northern
plains with a shortwave ridge over the upper Great Lakes this
morning. The closed low moves slowly east and moves an upper trough
into the upper Great Lakes this afternoon and tonight with the low
ending up near Thunder Bay Ontario by 12z Wed. Nam shows some 850-
500 mb q-vector convergence with some deeper moisture moving through
the area today and both exit tonight. Complicated forecast for today
as cold air moves into the area late today. Lake effect does not get
going until tonight and the wind direction does not really help
until late tonight as winds turn more westerly in the Keweenaw. This
was already covered in the forecast. Mixed pcpn this morning will
switch over to all snow late this afternoon with the arrival of the
colder air. Used the prob ice present to depict snow and a narrow
band moves through the cwa today with the cold front. Out ahead of
the cold front, removed snow out of the forecast and went with
drizzle, freezing drizzle and rain showers based on temperatures.
That was the only real big change to the going forecast.

.LONG TERM...(Wednesday through Monday)
Issued at 506 AM EST TUE DEC 6 2016

Very busy with the forecast for tomorrow through Fri night as a
couple shortwaves move through and colder air leads to LES.

Most uncertain with start times of the snow and associated
headlines. Don`t have a lot of time to provide details here so will
keep it brief. Models differ on if a compact SFC low will move
across northern Lake Superior Wed morning or if it will just be a
trough crossing as a shortwave moves across the area. If the low
develops, snow will likely move into the Keweenaw very early on Wed
(possibly even before 12Z) and may be very heavy. The GEM drops over
0.60" of QPF just Wed morning, which is backed up by the NCEP WRF
ARW. If that doesn`t occur, then amounts closer to what is in the
forecast are expected as flow will be WSW early and gradually
turning SW and W...then NW late. Models also differ on when to drop
the SFC trough across the rest of the area, which should allow for a
hefty burst of snow right along the trough. Set headline start times
to match best expectation for when the trough moves in, but
adjustments may need to be made. Another area of uncertainty is
eastern Marquette and western Alger Counties. Models show N to NNW
winds, which will drive the LES and the Lake Nipigon band somewhere
into this area. Of course, that makes the snowfall forecast highly
volatile in the north-central U.P. See the forecast and hazard
products for more info.

With focus on the forecast through Fri night, let blended
initialization handle the forecast from Sat on.

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 611 AM EST TUE DEC 6 2016

Band of light snow with a cold front will move across the area this
afternoon. Conditions will stay MVFR at KIWD through the period and
will stay MVFR through most of the period at KCMX. At KSAW, VLIFR
conditions in upslope flow will continue this morning in fog and low
clouds. Conditions will imrpove this afternoon with downslope flow
to IFR and then improve further tonight with drier air moving in.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 435 AM EST TUE DEC 6 2016

Period of active weather will continue this forecast period.
Gradient is expected to tighten up this morning with a period of
gales east of the Keweenaw over Lake Superior into early afternoon.
Gales in the far western portion of the lake this afternoon into
Wed. Another brief gradient increase will occur Wed, before winds
shift from southwest/west to northwest coupled with much colder air
flowing across the lake Thur into Fri. 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 7 AM Wednesday to 7 PM EST Friday
     for MIZ001-003.

  Lake Effect Snow Watch from late Wednesday night through Friday
     evening for MIZ002-004-005-009.

  Lake Effect Snow Advisory from 1 AM Thursday to 7 PM EST Friday
     for MIZ084.

  Lake Effect Snow Advisory from 1 AM Thursday to 7 AM EST
     Saturday for MIZ006.

Lake Superior...
  Gale Warning until 1 PM EST this afternoon for LSZ264>267.

  Gale Warning from 4 PM EST /3 PM CST/ this afternoon to 10 AM
     EST /9 AM CST/ Wednesday for LSZ162.

  Gale Warning from 4 PM this afternoon to 7 PM EST Wednesday for

Lake Michigan...


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