067
FXUS63 KMQT 101120
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
620 AM EST Fri Jan 10 2025

.KEY MESSAGES...

- Lake effect snow showers will develop behind a cold front
  early this morning into Saturday and press into the northwest
  wind snow belts. Snow accumulation associated with these
  showers may result in some hazardous road conditions.

- A Winter Weather Advisory is in effect for northern Gogebic
  and Ontonagon counties for this morning to Saturday morning.
  Generally 4 to 8 inches of fluffy snow is expected north of
  M-28, with isolated amounts up to a foot possible near the
  Porkies.

- Next system to bring widespread 1-4" of snow arrives on
  Sunday, continuing into Monday. Hazardous driving conditions
  are possible.

- Trailing lake effect snow is expected for early next week over
  the west becoming northwest wind snow belts.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 237 AM EST Fri Jan 10 2025

Broad troughing emanating southward from a closed upper level low
over northwest Ontario currently extends past the Texas/Mexico
border per GOES water vapor imagery and RAP analysis. While multiple
shortwaves are embedded within this trough, the one of interest for
Upper Michigan is currently pressing into western Lake Superior with
its surface reflection, a cold front, currently analyzed over
western Upper Michigan northward just east of the Keweenaw into Lake
Superior and Ontario. Webcams and radar reflectivities show a
narrow swath of snow accompanying the front, which is resulting in
some snow covered roads. Southerly flow off Lake Michigan is likely
supporting some light lake effect snow into eastern Upper Michigan.
Surface observations and webcams suggest this is east of our
forecast area, but I wouldn`t be surprised if some light snow is
falling in parts of eastern Luce. Mostly cloudy skies have kept the
region more mild then the past few nights. So far, temps have been
observed in the mid to upper 20s east, and teens to near 20 central
and west. Lakeshore areas and the Keweenaw are all currently
observing temperatures in the mid to upper 20s.

For the remainder of the overnight period and this morning, the cold
front will continue pressing eastward, pushing the swath of snow
through the forecast area. Guidance, supported by ongoing
observations, continues to suggest light snow is expected, with some
potential enhancement from the more moist southerly flow off Lake
Michigan later this morning into eastern Upper Michigan. This may
support amounts reaching an inch in parts of Luce before the frontal
precip ends. Behind the front, cyclonic flow with 850mb temps near -
12C will yield lake effect snow shower development. Expecting these
to press into the northwest to north-northwest wind snow belts
through the day and tonight, expanding eastward this morning and
early afternoon as the front exits. Model soundings suggest healthy
residency within the DGZ, particularly today into this evening
across the west and then late afternoon into tonight in the east.
Additionally, CAMs and some global models suggest an uptick in low
level convergence setting up along a lingering surface trough this
evening, which could further aid snowfall rates. At the moment, 0z
HREF suggests snowfall rates are most likely (75%+) to remain below
0.5 inches per hour, but localized terrain influences in the Porkies
could result in inch per hour rates at times. Overall, forecast
continues to reflect T to 2 inches in these snowbelts, with upwards
of 4 in Alger and 4 to 8 inches in northern Gogebic and western
Ontonagon through tonight. Localized pockets up to a foot will be
possible in the Porkies through tonight. Given the previous advisory
still looks good and the rates and amounts don`t justify adding to
it, will maintain the current advisories in Gogebic/Ontonagon for
the time being.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 421 AM EST Fri Jan 10 2025

Light LES continues into Saturday over the northwest wind snow belts
with 850mb temps over the lake between -11C and -14C, colder over
the west near the Keweenaw, and with Lake Superior at an average sfc
temp just shy of 4C. Decreasing cyclonic flow and weak sfc ridging
moving east into the Great Lakes turns winds southerly ahead of the
next system and shifts the weakening LES out of the UP. Otherwise
the day will be quiet with highs in the 20s.

Attention then turns to a clipper system which is the main focus of
the extended forecast. During the day Saturday, a shortwave trough
over the Northern Plains will be deepening as it swings toward the
Great Lakes. This shortwave reaches western WI and Lake Superior
Sunday morning as the closed low over Manitoba begins making its way
southeast toward the Great Lakes. From there, the shortwave pivots
over the Upper Great Lakes, eventually spinning around and phasing
with the closed low as it descends to the Upper Midwest/Great Lakes
for Tuesday. This brings a clipper low from ND on Saturday to near
La Crosse, WI by Sunday morning before it tracks northeast over
Upper MI and Lake Superior through Monday night. Ensemble guidance
generally has great agreement in the track and timing of the system
save for some of the Canadian suite which brings the low track
further to the south or the deterministic NAM which is quicker to
bring the low over the Great Lakes. The differences later in the
event will be driven more by the evolution of the closed low and the
shortwave phasing with it...which model guidance tends to struggle
resolving.

Despite these differences, there is fairly good confidence in the
forecast. WAA late in the day Saturday supports snow over the west,
which expands eastward across the UP into Sunday as the low moves
through the region. With northern Lake MI sfc temps around 5-7C and
850 temps over it around -8C to -9C, some lake enhancement along the
Lake MI shores is anticipated late Saturday night through Sunday.
Looking at model soundings, the depth of the moist layer increases
through the event, with a average DGZ depth of 4-7kft. With SLRs in
the teens and 6HR QPF around 0.1" (near 0.2" with lake enhancement),
up to 1-2" of snow per 6 hours is possible. Ensemble probabilities
of 24HR totals of at least 3" around 30-60%, focusing in on the lake
enhancement off Lake MI as well as over the western spine of Upper
MI with a transition over to LES. Current storm totals are between 1-
4" with higher amounts possible where there is lake enhancement. The
enhancement will depend greatly on the system track which means
confidence in storm totals is higher over the west. Some minor
impacts are expected, mainly over Menominee, Delta, and Schoolcraft
counties for snow covered roads. Winter Weather Advisories may be
needed with future forecast packages.

As the sfc low departs to the northeast, cold air filters in behind
it. 850mb temps drop to between -12C and -20C, colder over the
southwestern end of Lake Superior. This will support LES, into early
next week over the west wind snow belts on Monday, becoming
northwest for Tuesday into Wednesday. CAA during this period will
yield low temps below 0 Monday and Tuesday nights; wind chills
Monday night in the west may drop into the negative teens to near -
20 along the WI/MI state line. With the closed low likely dropping
south over the UP Monday night into Tuesday, LES looks to strengthen
during that period before gradually tapering out through the week.
Otherwise, light LES looks to continue next week until the next
shortwave arrives from the northwest.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 619 AM EST Fri Jan 10 2025

Cold front will move through the region this morning followed by
lake effect developing and pressing into Upper Michigan. At the time
of this discussion, the front had already passed KCMX and KIWD and
was approaching KSAW. Expect snow associated with the front to
linger for a couple hours at KSAW, followed by MVFR ceilings. There
some uncertainty on when the lake effect snow will get going and
move over KIWD/KCMX this morning, but expect it by afternoon and
then to continue into the overnight hours. Strongest showers may
yield IFR conditions, but MVFR is predominately expected. Lake
effect into KSAW is expected to begin late this afternoon. Shower
activity at all terminals will likely begin diminishing tonight.

&&

.MARINE...
Issued at 445 AM EST Fri Jan 10 2025

A cold front currently over central Lake Superior will continue
eastward through today with northwest winds mainly less than 20 kts
expected behind it. Reinforcing cold air this evening through
tonight will support some north-northwest winds up to 20-25 kts over
the east half of the lake. Winds settle below 15 kts Saturday and
Saturday night as weak high pressure ridging moves over the region.
A clipper low lifting through WI and Upper MI moves over the lake
Sunday night into Monday. Expect southeast winds of 15-25 kts over
the east half of the lake on Sunday ahead of the low. Winds then
increase from the north and eventually northwest behind the low to
20-30 kts Sunday night through Monday. There remains around a 25-50%
chance for low-end gales to 34 kts Monday and Monday night, highest
probabilities are over the southeastern portion of the lake (LSZ265
and 266). The higher winds look to remain over Lake Superior until
Tuesday evening as remnant troughing looks to keep cold air
advection going until the middle of next week. In addition to
helping sustain the higher winds, the colder air is also expected to
bring freezing spray across the lake Monday through Tuesday night;
some heavy freezing spray is possible Monday night into Tuesday
morning.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 7 AM EST /6 AM CST/ Saturday for
     MIZ002-009.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...JTP
LONG TERM...Jablonski
AVIATION...JTP
MARINE...Jablonski