Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 241909

Area Forecast Discussion
National Weather Service Marquette MI
209 PM EST Fri Nov 24 2017

.SHORT TERM...(Today and tonight)
Issued at 408 AM EST FRI NOV 24 2017

Main impacts for the short-term will be above normal temperatures
today with rain moving into the area and then colder temperatures
moving in tonight with light lake effect snow.

Today: Low pressure, sliding across Ontario this morning, will reach
western Quebec this evening. Ahead of the low, WAA increasing across
the Upper Great Lakes will allow isentropic ascent to linger across
the area as more moisture steadily flows across the region. This
will allow for isolated to scattered rain showers to continue or
slowly increase by mid to late morning. As the low continues
eastward throughout the day, a cold front sagging southward across
western MN this morning, will slide into the western U.P. by
around 18Z/24 and then to the far eastern U.P. by 03Z/25. Along
and ahead of the cold front/strong shortwave, widespread rain showers
will push through the Upper Peninsula as forcing is amplified.
Current thinking is that most areas will end up seeing between a
tenth and a quarter inch of rain. The strong southerly flow into
the area will allow temperatures to warm to above normal by this
afternoon with most area reaching into at least the mid 40s. The
favored south wind downsloping areas may end up seeing upper 40s.
It may not feel overly warm; however, as winds may gust to around
20 to 25 mph, which will make temps feel a bit cooler.

Tonight: The aforementioned cold front and low pressure system will
continue off to the east of the U.P. tonight. As this happens, winds
will become westerly this evening and then more northwesterly
overnight. At the same time, CAA will increase into the Upper Great
Lakes Region, with 850mb temperatures falling from around 2-3C this
evening to around -10C to -12C overnight. This will allow for
favorable delta-T values for lake effect snow. The most favorable
time for this to happen will be after 06Z as this is when the colder
temperatures advect into the region. Overall not expecting too much
in the way of accumulation as inversion heights are generally around
5kft and only a small portion of the moisture and convective cloud
layer are progged to be in the DGZ. At this point, have only a half
inch to an inch in the northwest wind favored snow belts. The
greater fetch over the eastern U.P. would lead to better chances
of seeing closer to an inch late tonight. Again, not expecting
too much, but it will be colder and roads may become a bit
slippery. Winds will be fairly gusty tonight, which will make it
feel much cooler. In fact, the favored westerly wind over the
Keweenaw may enhance the gusts a bit with gusts possibly reaching
between 25 and 35 mph tonight. Much of the rest of the U.P. may
see gusts around 15 to 25 mph. The northwest flow will allow waves
to build as high as 8 to 11 feet for locations east of Marquette.
This will lead to minor lakeshore flooding and beach erosion.

.LONG TERM...(Saturday night through Friday)
Issued at 156 PM EST FRI NOV 24 2017

...No widespread precipitation but could be breezy at times...

Strong west to east jet stream over the northern tier of the Conus
will persist through next week leading to a progressive and overall
warmer pattern. Could still be brief intrusions of cooler air this
weekend and again middle of next week with some light lake effect
but for most part a lower impact and quiet period is expected in
terms of larger scale systems. As a more stronger west to southwest
flow develops aloft next weekend downstream of deep trouging over
the western Pacific/western Conus, does appear a more prolonged
period of warmer weather could develop for the first full week of
December per CFS H5 height/H85 temp anomalies and latest 6-10/8-14
day outlooks from CPC.

To close the weekend expect broad ridge over western North America
with downstream troughing over eastern North America. Brief cold air
shot that brings lake effect early this weekend wanes Sat night but
another shot of colder air will move back in on Sun. May be a brief
period of gusty winds over 30 mph near Lk Superior as that cold air
moves in. Only shallow moisture shown in forecast soundings on Sun
but could be light lake effect over east. May end up only seeing
drizzle though as moisture only extends to temps of -8c which is
borderline to introduce ice in moist layer. Will keep it simple
with just mention of rain and snow showers attm. Any light precip
shuts down Sun night with winds shifting offshore as sfc high
brings in warmer south flow.

Sfc high moves to lower Great Lakes on Mon while stronger shortwave
over western Canada leads to deepening sfc low blo 990mb over the
Canadian prairies. South winds btwn the two sfc features will lead
to warmer conditions over Upper Michigan on Mon. Could be a lot of
mid and even lower clouds around (NAM shows more low clouds trapped
beneath inversion) but even so should see temps similar to what
occurred today (solid mid to upper 40s with even some low 50s). As
bulk of warmest air arrives late in the day on Mon maybe some light
rain could develop over the north. GEM more widespread with light
qpf compared to GFS and ECMWF. May turn breezy ahead of cold front
tied to the low. Strongest winds from southwest would be late Mon
into Mon night. Once cooler air works in Tue aftn and Tue night
could see lake effect for NW flow areas. GFS soundings are pretty
dry blo cloud base and H85 temps around -8c are marginal so any lake
effect looks very light. Gusty northwest winds over 30 mph could
develop along Lk Superior late Tue into Tue night. Temps will bounce
back quickly on Wed, then another shot of colder air moves back in
Thu-Fri of next week. Even with the changeable temps, quick moving
flow aloft looks to prohibit any big systems. However, there is a
hint especially from last few runs of ECMWF of a southern stream
rain/snow system lifting through on Thu with enough cold air behind
for light lake effect.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1241 PM EST FRI NOV 24 2017

VFR conditions will give way to MVFR conditions this afternoon with
a lowering of ceilings under areas of rain developing along and
ahead of an approaching cold front from the west. Behind the front,
winds will become gusty at each of the TAF sites; however, CMX will
be the most exposed and could see winds gusting as high as 35 mph
from the west and northwest. Light lake effect snow will be possible
late tonight into early Saturday morning; however, ceilings and
visibility restrictions should be limited with continued MVFR

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 408 AM EST FRI NOV 24 2017

South winds of 20 to 30 knots are expected to continue through
today. Gale force gusts to 35 knots are expected through this
morning so a gale warning remains in effect through mid morning for
most of Lake Superior. On the back side of the strong low pressure
system/cold front additional 35 knot gales are possible on colder
northwest flow into the area. Winds are then expected to remain in
the 20 to 30 knot range through at least mid week.

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


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