NWS Marquette, MI wrote its last area forecast discussion before the first event at Mar 28, 6:33 AM EST, 27 minutes earlier. Its key messages:
Area forecast discussion, Mar 28, 6:33 AM EST, 27 minutes before
Area Forecast Discussion
National Weather Service Marquette MI
733 AM EDT Fri Mar 28 2025
.KEY MESSAGES...
- Two rounds of impactful winter weather with widespread sleet,
snow, and freezing rain today through Sunday.
- Freezing rain will be heaviest from late this afternoon
through early Saturday morning, ranging from a light glaze
(far western UP) to 0.25-0.50in (Keweenaw, central, and
eastern UP).
- After a brief lull in wintry precipitation Saturday, a round
of wet, heavy snow and a wintry mix with sleet, freezing rain,
and rain is expected Saturday night through Sunday. However,
confidence is low on the location of the axis of heaviest
precipitation.
- Northeast gales of 35 to 40 knots are expected over the
western half of Lake Superior Friday afternoon through Sunday.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 433 AM EDT Fri Mar 28 2025
Low pressure is centered over South Dakota early this morning with a
frontal boundary stalled out over central WI out ahead of it.
Overrunning WAA has already brought 850mb temperatures above
freezing into the Upper Peninsula, though surface temperatures
remain generally in the upper 20s to near 30. Some weak radar
returns are apparent across the northern UP and Lake Superior, with
IR imagery likewise showing cooler cloud tops stretching out over
the area courtesy of a weaker midlevel shortwave rippling through.
Should anything touch the ground, soundings are yet cool enough for
mainly light snow from the Keweenaw to the far north-central and
eastern UP.
Into the daytime hours, the boundary across central WI heads
northward towards the UP as the low pressure system slowly tracks
into MN and eventually across WI tonight. Spotty, light
precipitation spreads in from the south, possibly starting as a
rain/freezing rain mix before changing over mainly to rain into the
afternoon with temperatures climbing generally into the mid 30s
area-wide. However, the higher terrain across the north-central
UP and the Keweenaw may stay cold enough for freezing rain to
persist into the afternoon. Snow and sleet may even linger
throughout the day in the Keweenaw with the warm nose not as
prominent.
This evening, expect precipitation rates to increase as the low
moves through WI. Simulated reflectivity courtesy of the CAMs
continue to favor the central and eastern UP for the heaviest
precipitation through the first half of the night, after which
precipitation slowly tapers off. Will also note several hundred to
almost 1000j/kg of elevated CAPE, as well as ~65kts of shear above
the inversion. Unsurprising, then, that CAM guidance looks rather
more thunderstorm-ey than would be expected from a winter event.
Could we be looking at marginally severe thunder-ice storms? The
main concern would be hail. As for ptype: soundings continue to show
a deep melting layer from around 10kft-3kft across much of the UP
(shallower and more elevated in the Keweenaw) with surface
temperatures near/below freezing. Thus, the dominant
precipitation type may end up being freezing rain or a freezing
rain/sleet mix. Will continue to allow for some snow to mix in
across the Keweenaw.
This will yield widespread ice accumulations of a quarter to
half an inch across the north-central and eastern UP (the Ice
Storm Warning areas), and a tenth to quarter inch in the
Keweenaw and the south-central UP. Lighter ice accumulations up
to a tenth of an inch are possible across Ontonagon and Gogebic
county tonight. Snow/sleet accumulations below an inch are
possible across the northern half of the UP, with up to 1-3in in
the Keweenaw. An additional concern across the Keweenaw and
near the Superior shoreline will be gusty NE winds that may
exacerbate impacts from accumulating ice and wet snow.
A brief lull in accumulating wintry precip is expected for the
daytime hours of Saturday ahead of another round for Sunday. More on
that below.
Winter Storm Warnings and Advisories and Ice Storm Warnings remain
in effect today through Sunday.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 454 AM EDT Fri Mar 28 2025
By Saturday morning and into the afternoon, precipitation across the
UP should be largely quieting down as the associated sfc low pulls
to the east and weakens further. Some lingering upslope driven mixed
precip is likely amidst northeast flow into the higher terrain of
Marquette/Baraga counties, but with soundings showing some drying
and cooling above 850mb, precip should slow to a drizzle. If the
elevated warm nose sticks around a bit longer than forecasted, this
could persist as freezing drizzle given sub-freezing sfc temps, so
be on the lookout for slick travel.
This reprieve in precip will be short lived as a second punch of
impactful winter weather is expected ahead of a developing CO low,
which tracks northeast along a tight baroclinic zone into Upper MS
Valley Sunday and continues through the Great Lakes Monday. With
this system, all precip types, including heavy wet snow, sleet, and
freezing rain are back on the table, and with a deeper surface low
and stronger fgen response expected, a swath of heavy wet snow will
spread *somewhere* across the west-central UP Sunday. However,
uncertainty remains quite high where these impacts will setup.
Despite only being roughly 48-72 hrs away, model guidance show
significant differences in where the low will track, which has major
implications for precip type and amount forecasting. The major 00z
ensemble suites (ENS, GEFS, and Canadian) have trended upwards in
terms of heavier QPF/snowfall amounts, but disagree on where. Both
the ENS and Canadian shift the heaviest axis further northwest into
the west-central and Keweenaw, while the GEFS is the further south
and east outlier, placing a swath of heavy wet snow by Monday
morning in the central UP. These models have not been very
consistent from run to run, either. Snow totals could range from a
few inches to potentially significant amounts, but details remain
uncertain and confidence remains low, so will just keep an eye on
trends for now. Moreover, with strong WAA aloft taking place, expect
additional mixed precipitation (sleet and freezing rain), especially
across the south-central and east UP. Latest 24hr 25-75th percentile
ice accumulations from the NBM by Monday morning range from nothing
at all to an additional 0.25"+, thus raising flags for an additional
significant hazardous travel period. Regardless, the heaviest QPF
(and thus greatest impacts) is expected late Saturday night
spreading west to east Sunday morning before gradually shifting
eastward away from the CWA Monday morning.
In response, we have gone ahead an extended the Ice Storm Warnings
in the east half of the UP through Sunday. These could be extended
to the south-central UP counties if the trends hold where Winter
Weather Advisories are already in place.
Given the wet, heavy snow (SLRs generally <10:1) and potential
additional ice accumulations, travel hazards and power outages are
probable even with a short break Saturday morning and afternoon.
Beyond this weekend, models at least agree that high pressure
ridging filters in behind the departing system into Tuesday,
offering an actual break from winter weather. But, in the spirit of
brief respites from active weather, guidance hints at yet another
potentially impactful CO low developing midweek, bringing additional
chances for ice and snow.
&&
.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 732 AM EDT Fri Mar 28 2025
Ceilings are lowering to MVFR this morning ahead of an approaching
winter storm. A further deterioration to IFR is expected mid-morning
onward as associated precipitation moves in - starting as a
rain/freezing rain mix, then transitioning mainly to rain for IWD
and SAW. CMX should continue to see frozen precipitation mixing in
this afternoon. Heading into the evening, a change mainly to -fzra
is expected, though some sleet may mix in overnight. Some thunder is
not out of the question for a brief period during the evening.
wintry precipitation begins to taper off after 06Z at IWD and CMX,
but fzrapl is expected to persist at SAW the rest of the forecast
period. NE Winds turn gusty this afternoon at CMX, remaining elevated
through the night.
&&
.MARINE...
Issued at 454 AM EDT Fri Mar 28 2025
Winds gradually pick up today ahead of a developing low pressure
system, eventually becoming northeast gales of 35 to 40 knots over
the western half of the lake this afternoon into Saturday. While
gales look to weaken late Friday night into Saturday, northeast
gales up to 35 knots are possible (~60% chance) in the western arm
of Lake Superior Saturday into Sunday ahead of a secondary system
moving northeast into the Great Lakes. Winds slowly back to the
north and eventually the northwest throughout the weekend into
Monday, becoming 20 knots or less again late Monday night. Expect
periods of mixed precip and heavy snow this weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Warning until 8 PM EDT Sunday for MIZ001-003.
Winter Weather Advisory from 8 PM EDT /7 PM CDT/ this evening
to 8 PM EDT /7 PM CDT/ Sunday for MIZ002-009.
Ice Storm Warning until 8 PM EDT Sunday for MIZ004-005.
Ice Storm Warning from 5 PM this afternoon to 8 PM EDT Sunday
for MIZ006-007-013-014-085.
Winter Weather Advisory until 8 PM EDT /7 PM CDT/ Sunday for
MIZ010>012-084.
Lake Superior...
Gale Warning from 2 PM EDT /1 PM CDT/ this afternoon to 6 PM
EDT /5 PM CDT/ Sunday for LSZ162-263-264.
Lake Michigan...
None.
&&
SHORT TERM...LC
LONG TERM...BW
AVIATION...LC
MARINE...BW