Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 142352
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
652 PM EST Wed Feb 14 2018

.SHORT TERM...(This evening through Thursday)
Issued at 349 PM EST WED FEB 14 2018

No major weather impacts expected; however, there could be some
light freezing drizzle over the Keweenaw Peninsula late tonight.
This may impact the Thursday morning commute.

Weak mid-level ridging and a warm advection sw flow under sunny
skies has resulted in afternoon highs today well into the 40s across
much of the west half of Upper Mi with even a few lower 50s
readings. Shattered the high temp record for the day here at NWS MQT
with a reading of 48F and it could still climb higher before the
day is over.

Tonight into Thursday: The fairly quiet and mild weather will
linger into the evening hours before a cold front approaches the
area overnight tonight and toward Thursday morning. This will lead
to increasing cloud cover across the area throughout the night.
Most locations will remain dry; however, as the front slides into
the northern portion of the area, mainly the Keweenaw late
tonight, the chances for precipitation will steadily increase. The
best chance would likely be between 09Z and 12Z. Along and
directly behind the cold front 850mb temperatures do not drop too
quickly. This, along with shallow moisture will lead to mainly a
light freezing drizzle potential late tonight over the Keweenaw
and across portions of the nw 1/3 of Upper Mi into Thu morning,
while most of the rest of the U.P. should stay dry. Some light
snow could mix in with fzdz from seeder feeder processes as mid
clouds move over the area ahead of the frontal passage. While not
expecting much in the way of ice accumulation, it doesn`t take
much freezing drizzle to make untreated roadways and elevated
surfaces slippery. Will have to keep an eye on this for the
Thursday morning commute.

Behind front 850 mb temps begin to fall enough Thu afternoon to
introduce ice crystals back into cloud layer so ptype should
gradually change over to all snow. Again since colder 850 mb temps
don`t arrive until Thu night, not expecting much snow accumulation
during day on Thu.

Expect lows tonight mainly in the 25 to 30 degree range with highs
on Thu from the upper 20s to mid 30s, coolest nw and warmest south
and east.

.LONG TERM...(Thursday night through Wednesday)
Issued at 253 PM EST WED FEB 14 2018

Main story in the long term is that after very quiet weather pattern
for much of February thus far, looks like a more active pattern will
be setting up into next week with multiple chances of system snow.
Temps will be variable but should end up around normal or above
normal. Will be colder to start long term Thursday night into Friday
Night, then it turns warmer Saturday into early next week. Probably
turns colder late next week. Latest GFS would be quite cold with
return to sub -25c H85 temps about 10 days from now. We`ll see on
that as, at least right now, blend of rest of guidance including the
previously warm GEM, do trend colder but not to the extent shown by
GFS.

Cold with light lake effect Thursday night into early Friday,
especially east. Lake effect will continue to be held down by
extensive ice on Lk Superior. Wind chills Friday morning over
southwest may be around 20 below, but don`t expect to reach advisory
criteria. Skies should clear out rest of Friday and with core of
coldest air retreating temps will reach mid to upper teens.
Southwest return flow kicks in Friday night and Saturday as low
pressure trough crosses northern Ontario and high pressure ridge
moves to lower Great Lakes. Could be a 3-6 hour period of light snow
on Saturday pretty much everywhere mainly due to forcing aloft. Low-
level dry air should limit snow amounts most areas to well under 1
inch though lift in the DGZ and added moisture off Lk Michigan could
help boost totals over the east to an inch or two. Cold front tied
to sfc low slides through Saturday evening. Cold enough and moist
enough in wake of the front for light lake effect for mainly west
wind snow belts. Extensive ice on Lk Superior should hold down snow
intensity.

By later Sunday, attn quickly turns to incoming area of H85-H7
moisture advection ahead of H85 low developing over northern Plains.
Broad divergence aloft from right entrance region of upper jet along
with Upper Michigan located to north of H85 baroclinic zone will
focus area of light snow spreading across Upper Great Lakes late
Sunday afternoon into Sunday evening. Main question is where will
these features line up as ECMWF continues to keep bulk of
forcing/snow farther north from northern MN across Lk Superior and
on the Ontario side of Lk Superior. GFS, GEM and ensembles keep axis
of snow more over Upper Michigan. This round of snow should taper
off late Sunday night. If axis of heaviest snow directly impacts
U.P, then isolated advisory amounts would not be out of question.
Though snow may not end completely late Sunday night into Monday
morning, it should taper considerably before primary sfc low over
the central Plains Sunday night moves to northern Ill/southern WI by
00z Tuesday. Slug of moisture advection and increasing forcing from
deformation and divergence aloft to north of sfc-H85 lows should
support widespread moderate snow which could impact parts of Upper
Michigan. Only negative is the sfc low is forecast to weaken as it
moves toward Upper Michigan. Based on H7 mixing ratios and blend of
model/ensembles qpf, think at least advisory snow amounts could
occur Monday and Monday night. GEM and GFS total qpf amounts over
0.75 inches would suggest even warning amounts could occur. Much too
early to focus on those specifics but think a weakening system
evolution would warrant going on the lower end of forecasted
qpf/snow totals at this time. Pretty early to get caught up in
details since would be occurring on day 5, but overall seems that
there are increasing signs for at least moderate system snow early
next week.

Even after initial system drifts east of area Tuesday into Wednesday
there could still be light snow or flurries as Upper lakes remains
within front edge of upper level troughing. High pressure eventually
brings cooler and drier air late next week. At least as it stands
now.
&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 652 PM EST WED FEB 14 2018

VFR conditions should prevail thru much of the night at
KIWD/KCMX/KSAW. However, given the melting snow that occurred today,
not out of the question for fog/MVFR vis to develop, mainly at KSAW.
Late tonight/Thu, a cold front will drop se across the area, leading
to the development of low MVFR/IFR cigs and some -fzdz/-sn, mainly
at KIWD/KCMX.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 349 PM EST WED FEB 14 2018

A few southwest gale force gusts are possible on Saturday, otherwise
winds will be blo gales through the forecast period.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

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



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