Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 012048

Area Forecast Discussion
National Weather Service Marquette MI
348 PM EST Thu Dec 1 2016

.SHORT TERM...(This evening through Friday)
Issued at 343 PM EST THU DEC 1 2016

Sfc low has moved east of Lk Superior but sfc troughing remains
across Upper Michigan and northern WI. Cool moist northwest flow
north of the trough is resulting in lake effect precip in the form
of mostly snow across the west half and mainly in the form of rain
across the east half of the cwa. Lake effect was heavier and more
widespread late last night into late this morning as a shortwave
wrapping around the western portion of the larger scale trough moved
across. Some higher terrain areas saw 2-4 inches of snow during that
time but based on web cams and sfc obs seems that the snow into this
aftn has become lighter. Expect marginal setup for lake effect to
continue through tonight and Friday with h85 temps -7c or so and
inversion heights around h85/5kft. Another couple of shortwaves
north of Lk Superior look poised to drop across Lk Superior and
parts of Upper Michigan later tonight into Friday morning. Stronger
forcing and deeper moisture look to mainly affect eastern cwa but
should see increase in lake effect for all areas as these waves
drop across similar to what occurred last night and this morning.

Additional snow amounts tonight into Fri morning will mainly be an
inch or two, but isolated higher terrain spots over the west and
maybe just inland from Lk Superior in the east could see higher
amounts of 3 to 4 inches. Only real bigger adjustment into Fri was
to ramp up pops over east cwa late tonight and Friday morning even
south to the Lk Michigan shore as that area will be most directly
impacted by the shortwave dropping down across eastern Lk Superior
and will have the advantage of being at the end of the longer fetch
with nw winds off Lk Superior. Consensus of probability of ice
present grids indicate that if enough deeper moisture does not
materialize, especially west, there could be some chance of drizzle
or freezing drizzle. Only have a slight chance of drizzle mainly
late tonight and into Fri.

Temperatures will fall back into the upper 20s tonight over the
interior west and central and that could lead to slippery spots as
moisture from the light snow today refreezes. Will mention that in
the hazardous weather outlook (HWOMQT). Farther east, temps will
fall into the lower 30s inland and stay in the mid 30s near the
shore. Should eventually see the rain near the shore mix with and
change to snow. Feasible it could stay warm enough right near the
shore to keep ptype mainly rain. Temps will stay cool on Fri with
low 30s over interior west and as warm as upper 30s near Lk Michigan
and over the far east.

.LONG TERM...(Friday through Wednesday)
Issued at 458 AM EST THU DEC 1 2016

Fri into Fri night: Models indicate the closed low over sw Quebec
will weaken and lift east toward New England late Fri. Behind the
low, cold air will linger over the Upper Great Lakes under a
cyclonic nnw flow. However 850 mb temperatures progged to be in the
-5C to -6C range will only be marginally cold enough to support lake
effect pcpn with Lake Superior sfc temps of 6-7C. Snow will be the
primary precip type although a mix of rain is possible along the
shoreline and east during the daytime hours on Fri. Given the
general absence of enhancement and a fairly elevated dgz expect any
snow accums to be inch or less.

Sat into Sat night: Light lake effect precipitation supported by low-
level convergence should be dwindling or ending over the east half
by afternoon or evening as the high pressure ridge axis moves across
Upper Michigan and winds back more west to southwest.

Sun into Sun night: Models indicate that the next shortwave trough
in zonal flow aloft will move in from the Northern Plains late Sun
into Sun night. Deep layer q-vector convergence ahead of this
shortwave will result in pcpn spreading w to e across the cwa on
Sun. Pcpn will be mostly in the form of snow over the west half but
will be more a mix of rain and snow east half due to moderation from
Lake Mi in southerly flow ahead of shortwave. 850 mb temps
-6 to -7c should be sufficiently cold enough given Lake Mi sfc temps
of 9C for some lake enhancement of pcpn into Schoolcraft and Luce
counties Sun into Sun evening which could produce some accumulating
snow well inland from Lake Mi. Given limited moisture inflow with the
system expect most system snow amounts to be generally less than an

Monday into Thursday: Models trending toward more amplified pattern
for next week as a 120+ kt 300-250 mb jet max and assoc shortwave
energy digging in from the eastern Pacific will carve out a broad
mid-upper level trough over the Western CONUS by early next week.
Model consensus of downstream ridging into the Great Lakes region in
response to the developing western CONUS trough will keep Upper Mi
mostly dry Mon into Mon night with a slight warming trend. Model
uncertainty increases from Tue into late week with the 00Z GFS being
much more progressive than 00Z ECMWF and Canadian with stronger
shortwave energy ejecting out of base of western CONUS trough. Given
uncertainty will use model consensus for pops which tend to keep
area dry from Mon into most of Tue but then brings in pcpn for Tue
night into Wed. Evolution/track of developing strong sfc low is very
much in question so initial pcpn for Tue night into Wed may end up
being more of a mix of rain/snow and then transition to more lake
enhanced/lake effect snow for late next week. Once cold advection
ensues behind the system, there will also likely be a period of
stronger winds accompanying lake effect snow later in the week.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1241 PM EST THU DEC 1 2016

Cyclonic nw flow on the backside of low pressure to east of Lake
Superior will result in mostly prevailing IFR conditions with -shsn
at KIWD and KCMX through this afternoon. Cigs will start out IFR
but will trend MVFR later today through the rest of the TAF period.
At SAW expect conditions mainly MVFR in occaisonal snow showers this
aftn and again late tonight into Fri. In between those time periods
late this aftn through most of tonight could see conditions become
VFR with even potential for clouds to briefly scatter out.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 343 PM EST THU DEC 1 2016

Surface low continues to drift east away from Lk Superior but
tighter pressure gradient across Lk Superior will keep nw winds 20
to 30 kts into Fri, strongest on the east half. High pressure moving
across will diminish the winds to 20 kts or less Fri night into the
weekend. Approaching low pressure trough for the middle of next week
will result in southeast winds increasing to 25 kts, strongest over
eastern sections.

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


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