Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 171023

Area Forecast Discussion
National Weather Service Marquette MI
523 AM EST Wed Jan 17 2018

.SHORT TERM...(Today and tonight)
Issued at 521 AM EST WED JAN 17 2018


Winds will gust to 35-45mph across the Keweenaw today, strongest
over the higher terrain and the NW side. This will lead to blowing
snow, which will cause visibility restrictions at times. CMX just
started observing blowing snow as the winds got to 25mph (gusting
35mph). Elsewhere over the north central and west, winds will
generally gust to 25-35 mph, which will lead to some blowing snow
in open areas, but not expecting coverage or visibilities to be
too bad.

Tonight, we could see some light lake effect snow over the Keweenaw
and near and E of Grand Marais, but no significant accumulations are
expected if snow does develop. This would be due to 875-900mb air
being around -10C and a SFC trough settling into southern Lake

.LONG TERM...(Thursday through Tuesday)
Issued at 410 AM EST WED JAN 17 2018

...Potential winter storm is still on track for Sunday afternoon
through Tuesday...

The early portion of the extended forecast, Thursday through
Saturday, is set to be fairly quiet. There are a couple chances of
snow or rain/snow chances as shortwaves slide through the area and
temperatures steadily warm. The first shot of mainly light snow
would be Thursday as a stronger/fast moving shortwave slides through
the north half of the U.P. the best moisture/forcing will likely
stay north of the U.P.; however, the Keweenaw and locations along
Lake Superior could see a quick dusting of snow through the day
Thursday. Another wave is expected to slide through the area Friday
and again, the better forcing is expected to stay mainly over Lake
Superior. Not out of the question to see some rain/snow showers over
the Keweenaw.  That shortwave will likely produce mixed
precipitation as warmer air continues to advect northward on
southerly flow into the Upper Great Lakes. Actually, it looks like
high temperatures will warm above normal with upper 30s to near 40
degree readings possible Friday and Saturday.

Attention then turns to a potential winter storm for Sunday
afternoon possibly lingering through Tuesday morning. Models are in
good agreement on the track of the system, developing the low over
the Plains/mid Mississippi Valley Sunday morning, and then lifting
the low north and eastward into northern Lower Michigan. This would
be a very favorable track for heavy snow potential across central
and western Upper Michigan. The system would likely have plenty of
moisture to work with as the southerly flow is progged to be wide
open to the Gulf of Mexico moisture source. If this all works out as
each of the models are showing, there could be several inches of
snow across much of western and central Upper Michigan. The features
that would be responsible for this potential winter storm are well
outside of the more densely populated observation platforms, so it
is expected that the exact patch of the low and associated heaviest
snow band will vary over the next few days. Additionally, on the
east side of the low there will likely be some mixed precipitation
along with a potential dry slot, which will both have an impact on
snow totals. Again, confidence in forecasting this potential winter
storm will increase over the next couple days as the system is
better sampled. At this point, it will definitely be worth keeping
an eye on for the potential of widespread heavy snow Sunday
afternoon through Tuesday.

Tuesday and beyond, a consensus of the model blends was used. This
gives intermittent chance of lake effect snow; however, exact
placement will be dependent upon wind direction and placement of the
aforementioned stronger storm system.

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1142 PM EST TUE JAN 16 2018

Westerly winds will increase and become gusty through the morning
and afternoon hours at all TAF sites. These winds will allow blowing
snow given the fluffy nature of the recent snowfall, especially at
KCMX and KSAW where at times visibilities may drop down towards
MVFR/IFR category. Even though winds will be rather gusty at
times, model guidance still show very strong winds just off the
surface, with upwards of 45 to 55kt around 2000ft AGL. Therefore,
have maintained mentions of low-level wind shear. Winds will
gradually subside towards the end of this TAF period along with
any lingering visibility restrictions from blowing snow.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 521 AM EST WED JAN 17 2018

W to WSW gales to 40 knots are expected today before diminishing
this evening. Heavy freezing spray is also expected across the
western lake this morning. Otherwise, no gales are expected through
the upcoming weekend.

Upper Michigan...
Lake Superior...
  Gale Warning until 7 PM EST this evening for LSZ267.

  Gale Warning until 10 PM EST this evening for LSZ265-266.

  Heavy Freezing Spray Warning until 11 AM EST /10 AM CST/ this
     morning for LSZ162-263-264.

  Gale Warning until 1 AM EST /midnight CST/ Thursday for LSZ162-

Lake Michigan...


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