Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 061819

Area Forecast Discussion
National Weather Service Marquette MI
119 PM 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 110 PM EST TUE DEC 6 2016

Narrow band of moderate snow was approaching KIWD stretching
southeast, and this band will continue to lift northeast towards KCMX
later this afternoon. CIGS are mainly MVFR across TAF sites, but
expect some light snow/rain and possibly fzra/sleet may accompany
precip between 23z and 01z before it transitions over to all snow for
KSAW. At KCMX precip should remain as all snow through TAF period,
however a brief lull in snow does appear favorable with some minor
improvements to CIGs back to MVFR and possibly VFR. Winds will be on
the increase from the southwest overnight, with gusts developing to
around 28-32kt thru daybreak Wed. Lgt snow will redevelop and coupled
with the gusty winds will likely further reduce VSBYs by daybreak Wed
with low end MVFR conds returning.


.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 1 AM Thursday to 7 AM EST
     Saturday for MIZ006.

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

  Lake Effect Snow Advisory from 7 AM Wednesday to 7 PM EST Friday
     for MIZ001-003.

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

Lake Superior...
  Gale Warning until 10 AM EST /9 AM CST/ Wednesday for LSZ162.

  Gale Warning until 7 PM EST /6 PM CST/ Wednesday for LSZ240>243-

Lake Michigan...


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