384
FXUS63 KMQT 121333
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
933 AM EDT Wed Mar 12 2025

.KEY MESSAGES...

- Mainly warmer than normal temperatures are expected into the
  weekend. This will lead to melting snowpack and increasingly
  dangerous ice conditions on lakes and rivers.

- Widespread rain chances this weekend before changing over to
  snow Sunday. Heavy snow is not expected at this time.

&&

.UPDATE...
Issued at 933 AM EDT Wed Mar 12 2025

The back edge of light flurries/snow showers is moving northward
through the UP this morning, but light amounts of snow (mainly trace
accumulations) are still possible across the northern half of the UP
before snow wraps up into the afternoon. Otherwise, the forecast
remains on track.



&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 228 AM EDT Wed Mar 12 2025

A weak trough moving through early this morning is bringing mid-
level cloud cover to the region, with radar imagery showing returns
of generally around 10 dbz or less above the surface. However, given
the somewhat dry air at the surface and weak forcing in the lower
levels associated with the trough, light snow will have a difficult
time getting to the ground. While a few spots may see a light
dusting by the time the sun rises, only flurries are expected across
the area, if even that. As the sun rises, expect the last of the
light snowfall to leave the Keweenaw late this morning, with a
transition or mix over to sprinkles possible over a few spots as
warmer temperatures move into the U.P. from the west throughout the
day. Expect a return to above-normal temperatures today, with the
increasing sunniness throughout the day helping the area to feel
Spring-like by the afternoon hours, especially over the west half
outside of the Keweenaw. Expect highs to get into mid to upper 30s
over the Keweenaw and east, and the low to mid 40s over the rest of
the U.P. today; watch out for thin and unstable ice conditions
given the warmth!

&&

.LONG TERM /TONIGHT THROUGH TUESDAY/...
Issued at 321 AM EDT Wed Mar 12 2025

Building height rises behind a low amplitude shortwave this evening
usher in quiet and warmer weather through at least Friday afternoon.
Overnight lows tonight/Thur morning will be fairly seasonable in the
20s region wide before temperatures begin to climb through the rest
of the day, peaking in the mid-50s close to the WI stateline and mid
to upper 40s along the Great Lakes.

From a meteorological perspective, the fun beings to ramp up Friday
in the form of an anomalously deep negatively tilted trough that
swings across the western CONUS, inducing strong sfc cyclogensis out
of the Front Range Friday morning. Ensembles quickly eject a deep
~975 low pressure northeast, reaching the KS/NE border by Friday
afternoon. Warm southerly flow ahead of this feature surges
northward into the UP, pushing daytime temperatures into the 50s
across the entire CWA, with favorable probability (>50% for highs
near 60 interior west and central. Given that recent warm days have
far exceeded NBM temperatures, current thinking is that this
probability is too low and it would not shock me to see a 65F
somewhere close to the state line. Also, overnight lows into
Saturday and Sunday may not dip below freezing, especially across
the south and west. As the deep trough and sfc low continue trekking
northeast, WAA along and ahead of the warm/occluded front will begin
to spread rain across the Upper Great Lakes late Friday through much
of Saturday before changing over to mix/snow Sunday. Guidance
suggests 24 hr QPF through 00z Saturday between 0.1 and 0.5", which
in tandem with melting snowpack and existing frost depths, will be
worth keeping an eye on. No flooding impacts are currently expected,
though if you have property near a river or lake that has previously
experienced flooding or runoff issues from early spring
rains/snowmelt, it may be worth necessary preparations.

Another aspect of the forecast worth watching will be the potential
for the first thunder of the year, as the ENS shows significant
MUCAPE on the order of 200-450 J/kg Friday through Saturday morning,
though it is all elevated, so enough questions remain about the
potential to realize such instability to keep thunder out of the
forecast for this package. With a ~980mb low encroaching the western
UP Saturday, one would expect fairly strong gradient winds through
much of the weekend, though surprisingly gridded forecast guidance
is rather lackluster on the magnitude of winds prior to the cold
fropa Sunday morning. As noted previously, suspect that CAMs will
provide a boost to the wind forecast over the coming days.

With cool northwesterly flow expected to follow the passage of such
a trough, lake effect snow showers are possible (30-50%) Sunday as
Lake Superior remains wide open and 850mb temps drop to the mid-
negative teens, though height rises aloft with approaching ridging
may spoil conditions by midday Monday. Uncertainty is high given the
spread in PoPs between the NBM and LREF, but with some dry air also
expected behind the low, expecting sub-advisory LES once all is said
and done. Looking further ahead in the forecast, uncertainty grows
into next week, though the GEFS is already taking aim at another
Colorado Low for the middle of next week, though spread is high
enough that it is only worth keeping an eye on rather than getting
too worked up in the details.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 659 AM EDT Wed Mar 12 2025

VFR conditions are expected to hold across the area today through
tonight. However, there is around a 30% chance that CMX and SAW
could see MVFR cigs for a short time this morning in the light snow
showers/flurries. However, the threat for snow showers looks to end
by 15z. Light southerly winds (looking to become easterly over CMX
late this afternoon) look to dominate the daytime hours before winds
turn southwesterly tonight.

&&

.MARINE...
Issued at 321 AM EDT Wed Mar 12 2025

Even as high pressure departs the region through the midweek time
period, a slackening pressure gradient in the absence of strong
pressure features will keep wind gusts at or below 20 kt through
Thursday night. Friday will begin a gusty period as a deepening
Colorado Low tightens the pressure gradient against high pressure
over the Canadian Maritimes. Southeast winds will gust to 20-25 kt
by Friday afternoon over the east half of the lake, with easterly
wind gusts to 25 kt spreading to the west half of the lake overnight
into Saturday. Then as the unseasonably strong low pressure cuts
across western Lake Superior late Saturday unto Sunday, westerly to
northwesterly winds quickly ramp up to gales to 35 kt Sunday morning
over the west half of the lake and gusts to 30 kt over the east.
Gales to 40 kt spread to the east in the afternoon hours with gusts
to 45 kt possible (~40%) near the upper entrance of the Portage
Canal. Winds fall below gales Sunday night and below 25 kt early
Monday morning as winds shift to the west. Uncertainty grows in the
late period of the forecast but winds are generally expected to be
in the 20-25 kt range. Light to moderate freezing spray is forecast
in the wake of the low, especially in the east half of the lake
Sunday night. The long-duration southeasterlies will allow waves to
swell to 7-9 ft east of Isle Royale by Saturday morning, though the
highest waves in this forecast period will be in the northwest flow
behind the low Sunday, with widespread 6-9 ft waves and waves up to
10-13 ft in the eastern quarter of the lake Sunday evening.

&&

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

&&

$$

UPDATE...LC
SHORT TERM...TAP
LONG TERM...BW
AVIATION...TAP
MARINE...BW