Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 222006

Area Forecast Discussion
National Weather Service Marquette MI
306 PM EST Wed Nov 22 2017

.SHORT TERM...(Today and tonight)
Issued at 445 AM EST WED NOV 22 2017

LES has diminished rather quickly early this morning as a result of
dry and warmer air moving over Lake Superior. Will continue to see
LES diminish and drift offshore today as a SFC ridge moves through.
No additional significant accumulations are expected.

Could see some light snow along the WI border this evening into
tonight as a shortwave moves nearby, but nothing that would produce
significant impacts. With SW to W flow, there could be some light
lake effect/upslope snow over the Keweenaw tonight. Could see up to
an inch of snow over the Keweenaw.

.LONG TERM...(Thursday night through Wednesday)
Issued at 305 PM EST WED NOV 22 2017

...Up and down temperatures into next week with brief shot of lake
effect on Sat...

Upper air pattern late this week features trough over western Canada
sliding toward the Great Lakes while ridge builds over western Conus
and western Canada. Associated sfc low with the advancing trough
will deepen to 980-985mb as it reaches central Manitoba on Fri
morning. Warm air moving in ahead of the low along with some mid-
level moisture could support some light precipitation late Thu night
into Fri morning, especially north and east where sufficient
saturation for precip looks like better bet. Looks like there is
enough warm air sfc and aloft to keep ptype rain if it occurs.

Fri will be breezy (SW winds 20-30 mph with higher gusts possible)
with temperatures rising above normal (h85 temps upwards of +10c
supporting highs well into the 40s some areas) as Upper Lakes is
within warm sector of the deep sfc low crossing into northern
Ontario. Could be even warmer if there were not as many clouds
around. Day will be mostly cloudy to start with plenty of mid
clouds, then shortwave driving in from northwest through the day
will eventually spread rain showers back over the forecast area
through the aftn. Any precip should stay rain until later Fri night
when it changes back to snow as colder air moves back in behind the
cold front tied to the low. Not expecting widespread snow though as
most of heavier precip with the system will be out of the area by
time change over occurs.

On Sat, polar jet digs across Lk Superior and Upper Michigan. Upper
trough will deepen over Great Lakes and colder air (H85 temps as low
as -13c) will move across the region. After the warmer temps on Fri,
high temps on Sat will be in the 20s west to low 30s east. Temps may
fall through the day in some areas. WNW-NW winds will result in lake
effect snow. Snow showers could be heavy at times as cold air first
charges in, but lake effect should diminish by Sat night as synoptic
moisture exits and inversions up to 6-7kft fall with arrival of
anticyclonic flow as high pressure builds from central Canada to the
Upper Great Lakes and middle Mississippi River Valley. Overall the
snow amounts from the lake effect should stay in check with limited
synoptic support. Bigger impact could be from reduced vsby at times
in snow/blowing snow as northwest winds gust to 30-40 mph. Overall
could see similar conditions on Sat to what just occurred on Tue.

Lake effect diminishes Sat night into Sun, hanging on longest over
east forecast area. Ridging then builds in sfc-aloft by Mon. Temps
should stay in the 30s on Sun, but then could rise well into the 40s
on Mon. Signal in some of the guidance that with main trough/jet
streak west and north and sfc low well to the north, Mon could end
up being fairly sunny. If that is case, which is certainly tricky
this time of year, temps in some areas could reach 50F. Following
the warm up, latest GFS quite aggressive in return to upper
troughing/cold air mid week while ECMWF/ensembles and GEM keep it
warmer. GFS not agreeing well with NAEFS ensembles either. Probably
will see temps cool back mid to late next week but probably not to
the degree that the latest GFS is showing. Return to cooler weather
could come with a storm system, but per ensembles, probably not to
the extent 12z ECMWF shows with strong system over the Great Lakes
late next week.

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1241 PM EST WED NOV 22 2017

Lingering MVFR clouds at KCMX and KSAW will dissipate or lift out
of the area by mid afternoon leaving VFR conditions for the rest
of the foreast period. Mainly mid and high clouds will then
prevail with the potential for light snow or flurries at KIWD and
KCMX late this afternoon and evening.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 445 AM EST WED NOV 22 2017

Winds will back to the SW up to 20 to 30 knots today through
tonight. Westerly winds of 20 to 30 knots Thursday will back to the
south on Friday. Another strong low pressure system will then bring
the potential for northwest gales of 35 to 40 knots Friday night
into Saturday.

Upper Michigan...
Lake Superior...
Lake Michigan...


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