Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 052014

Area Forecast Discussion
National Weather Service Marquette MI
314 PM EST Mon Dec 5 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 314 PM EST MON DEC 5 2016

Visible imagery across much of the Upper Peninsula have cleared this
afternoon, with the exception of the Kewennaw Peninsula where a
stratus deck lingers. As skies have cleared the pressure gradient
has remained light, which has allowed surface winds to remain
southwesterly and light or less than 10 mph. The next system remains
well upstream of the region across the Northern Plains and progged
to lift further North later tonight. Meanwhile mid-lvl heights will
also increase. Simultaneously warm air aloft will advect north this
evening ahead of the shortwave, as guidance indicates a better
inversion developing as the cold air becomes trapped.

With the warmer air advecting north tonight, moisture is expected to
accompany the airmass  which is present currently across Wisconsin.
This cloud cover/moisture will thicken across Upper Peninsula and
guidance is indicating drizzle/lgt-precip will develop. The
challenge is on what type of precip will fall, which thermal
profiles support the potential for a wintry mix although main
elements will likely end up being lgt snow or rain mixture. If
clouds are delayed from arrival, the shallow cold layer could
resultin increases chances of any precip falling as freezing
drizzle/fzra and snow. Any accumulations are progged to be less than
one inch across the higher terrain, as qpf from the event overnight
will struggle pushing into diffluent mid-levels.

Winds will be on the increase and turning southerly/southeasterly as
the shortwave lifts to the Northwest of the Arrowhead of MN Tue.
Clouds are expected to remain, the challenge will be on will any
lingering drizzle/flurries continue into midday/aftn Tue. Temps are
likely not going to warm much, so have only made minor adjustments
to going forecast of the low/mid 30s, possibly upper 30s east of

.LONG TERM...(Tuesday through Sunday)
Issued at 430 AM EST MON DEC 5 2016

Main attention continues to be Wed through at least Fri night as
significant LES kicks in.

A low pressure system will gradually move from northern MN Tue
through Ontario and into Quebec by Thu. Cold air moving in with the
system will lead to WSW wind LES on Tue night will probably impact
the Keweenaw, accumulations should be on the light side as 850mb
temps will only be around -9C. Winds will gradually turn W on Wed as
the system moves E, with light LES continuing.

Most attention is on Wed night into Fri along and behind a shortwave
and SFC trough/cold front that moves through. 850mb temps fall to
around -15C on Thu, which when combined with the other forcing
mechanisms leads to potential for moderate to heavy snow in the NW
wind snowbelts, and briefly along all of the north shores of the
U.P. as the trough passes. Only have snowfall amounts through Thu
right now, but an early prediction of up to around a foot of snow
just Wed night through Thu for the W and NW, and around 6 inches E
near Lake Superior. Additional persistent snowfall into Fri will add
to those totals. Exactly how long the LES continues is uncertain as
models differ on when to switch flow around to the south. The ECMWF
if faster in doing so on Fri, while the GFS doesn`t switch winds the
southerly until Saturday morning. Blowing snow will also be an issue
along Lake Superior Wed through Fri. Plenty of uncertainty for the
weekend and early next week, so just let the blends handle that.

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1249 PM EST MON DEC 5 2016

Visible imagery this morning had shown a narrow wedge of clearing
taking place just north of KSAW stretching east along the Lake
Superior shoreline. Then on the western edge of the clearing was
another channel of IFR cigs, with a second clearing wedge across
Northern Wisconsin towards KIWD. Early this afternoon the narrown
channel of low clouds had slowly lifted towards an MVFR deck with
only a few pockets of IFR lingering. Closer to KCMX low cigs
lingering but was at MVFR conds. Winds remained light as well
generally from the southwest; however, as a system continues to
develop later tonight flow will turn southerly to southeasterly
after midnight. Looking well south/southwest of the area and clouds
have already begun to advance. Expect the thicker clouds to develop
overhead late this afternoon/early evening. This will then bring
increased moisture chances later this evening from southwest to
northeast. With temperatures expected to moderate aloft, this may
result in temperatures closer to the surface remaining near freezing
and could allow the precip that develops to fall as a light wintry
mix of sleet/freezing-rain/lgt-snow. In addition to the precip types
possible tonight, low-cigs will also return and could see IFR conds
redevelop after midnight through daybreak Tuesday.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 314 PM EST MON DEC 5 2016

Period of active weather is expected to ramp up towards the middle
of the week. Gradient is expected to tighten up tonight, with a
period of gales east of the Keweenaw over Lake Superior thru midday
Tue. Winds may approach gales in the far western portion of the lake
Tue eve. Then 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 Superior...
  Gale Warning from 7 AM to 1 PM EST Tuesday for LSZ266-267.

Lake Michigan...


SHORT TERM...Beachler
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