Area Forecast Discussion
Issued by NWS Marquette, MI

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211
FXUS63 KMQT 230532
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
1232 AM EST Thu Nov 23 2017

.SHORT TERM...(This evening through Thursday)
Issued at 403 PM EST WED NOV 22 2017

WV imagery and RAP analysis indicated a mid/upper level ridge from
the sw CONUS into BC/Alberta and a trough over the east resulting in
nw flow through the nrn Great Lakes. At the surface, sw flow was
increasing as a ridge moves east from the cntrl Great Lakes and a
trough edges through the plains. The broad WAA pattern supported
some light snow from ern MN into wrn WI with the lowest vsby only to
around 3sm. Radar returns into the wrn cwa remained aloft with only
mid clouds observed in the very dry airmass, per 12z KMPX/KGRB
soundings.

Tonight, Although the stronger isentropic lift and greater moisture
slide mainly south of the cwa per radar/satellite trends, some light
snow may be possible over the far west early this evening. As the sw
winds over Lake Superior veer wrly overnight some lake enhanced snow
may also develop into the Keweenaw. However, instability will be
limited with 850 mb temps only to around -8C.

Thursday, winds will veer enough to bring any light LES into the far
ne cwa east of Munising. Otherwise, a sfc ridg building into the
area will bring some clearing with some sunshine especially over the
south. This will help push temps into the mid to upper 30s.

.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 06Z TAFS through 06Z Thursday night)
Issued at 1232 AM EST THU NOV 23 2017

An upper disturbance moving through the area will result in
-shsn/flurries mainly at KCMX as winds turn to an onshore westerly
direction at KCMX overnight. Cigs will lower to MVFR at KCMX under
light shsn before improving to VFR Thu afternoon. Otherwise expect
expect VFR conditions throughout the forecast period at KIWD and
KSAW. LLWS is expected to develop late Thu evening mainly at KIWD as
a low-level wind max noses in from the west.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 403 PM EST WED NOV 22 2017

SW winds up to 30 knots will veer to the west late tonight into
Thursday and then 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.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
  Gale Watch from late tonight through Friday evening for LMZ248-
     250.

&&

$$

SHORT TERM...JLB
LONG TERM...JLA
AVIATION...Voss
MARINE...JLB



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