Winter Storm and Winter Weather in Michigan, December 4 to 5, 2024

Area Forecast Discussion
National Weather Service Marquette MI
509 AM EST Wed Dec 4 2024

.KEY MESSAGES...

- Quick-hitting clipper continues to bring widespread snowfall
  of 2-4 inches, locally up to 6-8 inches in the east through
  this morning.

- Heavy lake effect snow bands will develop today for the
  northwest belts, shifting to the northerly belts late tonight
  into Thursday. The combination of heavy snow and blowing snow
  will lead to dangerous travel conditions and near-zero
  visibility in heavy snow bands. Winter Storm Warnings and
  Winter Weather Advisories are in effect.

- Blustery northwest winds, gusting up to 30-45 mph are expected
  this evening into Thursday morning, especially near Lake
  Superior and in the Keweenaw. During this period, wind chills
  drop to near 0 over the east and into the single digits below
  0 central and west.

- Storms to 50 knots develop across the entire lake this
  afternoon through Thursday morning.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 509 AM EST Wed Dec 4 2024

996 mb Clipper system is well-defined on current water vapor
imagery/surface analysis early this morning with center located over
south central Ontario (just north of the northern Lake Superior
shoreline.) Best isentropic ascent ahead of the low has already
pushed into the eastern half of Upper Michigan per latest radar
mosaic. It will, however, be counteracted by an impending dry slot
this morning. Nonetheless, with some Lake Superior and MI
enhancement, the Keweenaw and eastern counties would still see some
3 to 5 inch accumulations with localized higher amounts through this
morning making the morning commute especially hazardous across the
east. Through the course of the day, the mid-level trough will drop
into the area behind the system's cold front accompanied by strong
CAA. This will drop 850 mb temps back into the -20C to -12C range
and a transition back into a NW wind lake effect snow pattern. With
snow bands now expected to extend farther inland, have upgraded Iron
and Delta Counties to Warnings and have put Dickinson under a Winter
Weather Advisory starting at Wed 18Z. Meanwhile, WNW winds will be
strong with gusts as high as 35 to 40 mph, resulting in areas of
blowing snow and visibilities less than a quarter mile in the
heaviest bands. This combined with temperatures falling into the
teens through the afternoon will make this a particularly hazardous
situation.

&&

.LONG TERM /TONIGHT THROUGH TUESDAY/...
Issued at 421 AM EST Wed Dec 4 2024

Moderate to heavy LES will continue into tonight, initially over the
NW wind snow belts. This quickly shifts N late tonight into Thursday
as the clipper low departs east to southern Quebec, a frontal
boundary drops south across the region in its wake (between 0-6Z
Thursday), and high pressure descends into the Plains. Lake Superior
temps have dropped to around 7C and 850mb temps dropping over the
lake initially will be around -20C to -12C (colder west), but even
out to around -12 to -18 for Thursday. This results in delta-Ts of
up to 28C in the west and 20C in the east this evening, rounding out
to around 20-25C for Thursday. Low level convergence will also be
strong and widespread along the lake Superior shores tonight with
model soundings showing good lift and moisture extending through the
DGZ and up to inversion height of 5-7kft; higher in the east where
there also is longer residence time over the lake. SLRs are expected
in the upper teens to around 20:1. QPF in the western high terrain
early on tonight could see up to 0.2-0.25" in 6 hours where NW
upslope flow is optimized. The north central and east will see the
upstream pre treatment from Lake Nipigon, also resulting in periods
of 6hr QPF up 0.25". This heavier LES shifts from the east to
north central as mentioned earlier. Otherwise, NW to N LES snow belts
should generally see a few hundreths to 0.15" per 6hr period tonight
with lower amounts into Thursday. Total QPF in the south central UP
likely will remain less than 0.1" during the LES event. LES totals
tonight: 2-8" in the NW becoming N wind snow belts, trace to 2" in
the south central. Opted to upgrade Iron and Delta counties to
Winter Storm Warnings and add a Winter Weather Advisory for
Dickinson county this afternoon into Thursday.

Other impacts tonight will revolve around the gusty northwest
becoming northerly winds tonight into Thursday as a result of the
strong pressure gradient expected over the UP. Gusts to 30-40 mph
are expected to be fairly widespread overnight into Thursday with
model soundings indicating potential for isolated gusts up to 45+
mph. Gustier winds are expected near Lake Superior and in the
Keweenaw where gusts up to 50 mph are possible. Rapid drops in
visibility are already likely in heavy LES (snowfall rates up to
1"/hr at times), but blowing snow is also a increasing factor in
hazardous travel into Thursday. Some power outages are also
possible. With temps falling into the teens early on, wind chills
are expected to drop near 0, warmer in the east and by the
lakeshores. Strong winds across the lake will also build up wave
heights above 8 feet along much of the Upper MI shores; some minor
lakeshore flooding and beach erosion is possible late tonight into
Thursday.

With increasing anticyclonic flow on Thursday, drier air advecting
in, inversion heights lowering, and low level convergence weakening:
LES weakens, especially over the west with closer proximity to the
descending high pressure. That said, northerly winds hold on until
later in the day, keeping some lighter accumulations of up to 4"
over the north central and east Thursday into Thursday night.

Thursday night the high pressure settles to the Lower Mississippi
Valley, winds back westerly and lingering LES lifts to the west wind
snow belts for Friday in response. Meanwhile, a mid level shortwave
arrives to the Upper Great Lakes for Friday. While there is pretty
good placement and timing agreement on the shortwave, the sfc
features still could use some clarity. 850 mb temps do yield
sufficient delta-Ts for LES W wind snow belts. Accumulations look to
remain below 2". With confidence still low and expected system to be
on the lighter side, opted to keep chance PoPs for now save for the
far east where the best LES is possible.

A brief pattern shift on Saturday to quasi-zonal flow for Sunday
into Monday with WAA throughout brings a brief warm up to the
region. Highs Saturday - Monday increase to the 30s with lows mainly
in the 20s. Ensemble spread is still significant Sunday into next
week, but the active period is progged to continue with multiple
systems quickly moving into the Great Lakes region. A return of some
rain to the central and eastern UP is possible with the early next
week system before a colder airmass returns.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1222 AM EST Wed Dec 4 2024

The initial batch of snow is moving through the UP tonight with a
clipper low quickly tracking into Ontario. MVFR ceilings will be
favored at all terminals through the forecast period, but visiblity
remains more variable. MVFR to occasional IFR visiblity is expected
with light to moderate snow tonight, then a brief improvement in
visibility is possible into the early morning hours at IWD and SAW
with a brief dry period. However, visiblity restrictions likely hang
on at CMX the rest of tonight as winds veering more to the west kick
off lake effect snow there. Winds continue to veer to the NW into
Wednesday, bringing in lake effect snow and associated MVFR/IFR
visibility back into IWD and SAW. As winds turn to the NW by
Wednesday afternoon, they'll become gusty with 30 kt gusts becoming
likely (60+%) at all terminals after 18Z. The combination of wind
and snow could create a BLSN threat especially at KCMX Wednesday
afternoon.

&&

.MARINE...
Issued at 421 AM EST Wed Dec 4 2024

Some isolated gale force gusts to 35 kts are possible yet in the
west this morning, otherwise southwest winds 20-30 kts are expected
ahead of a cold front. As the clipper system moves just north of the
lake today, a cold front sweeps across the lake increasing northwest
winds to 45-50 kts from west to east this afternoon and evening.
Strongest winds are expected tonight between 1 AM and 7 AM EST
Thursday in the north central and eastern portions of the lake where
gusts up to 55 kts are possible (30-50% chance). North-northwest
gales Thursday morning gradually fall below 34 kts by the afternoon
in the west and by the evening in the east. 20-30 kt winds gradually
fall to around 15-25 kts for Thursday night, backing west by Friday
morning. West winds continue through Friday, veering northwest
briefly for Friday night, then backing southwest for Saturday into
Saturday night. Westerly winds are expected for much of the day
Sunday.

Behind the cold front today, waves build up to 10-16 ft. Wave
heights over the west hold steady tonight and increase up to 15-20
ft over the east by Thursday morning. Highest waves are expected
between Stannard Rock, Marquette, and Grand Marais. Waves then fall
below 4 ft in the west Thursday evening and Friday morning in the
east. Across the lake, waves between 3-6 ft are expected on Friday.
Waves then remain at or below 4 ft the rest of the weekend. With the
cold airmass surging in tonight and increasing wave heights, some
freezing spray is expected. The main area of concern for freezing
spray is the west half of the lake this afternoon through tonight.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Storm Warning until 1 PM EST Thursday for MIZ001-003-
     006-007-014-085.

  Winter Storm Warning from 10 AM EST /9 AM CST/ this morning to
     7 AM EST /6 AM CST/ Thursday for MIZ002-004-009-084.

  Winter Storm Warning from 1 PM this afternoon to 7 PM EST
     Thursday for MIZ005.

  Winter Storm Warning from 1 PM EST /noon CST/ this afternoon
     to 1 PM EST /noon CST/ Thursday for MIZ010-013.

  Winter Weather Advisory from noon today to noon CST Thursday
     for MIZ011.

Lake Superior...
  Gale Warning from 4 PM this afternoon to 1 PM EST Thursday for
     LSZ251-267.

  Gale Warning from 10 AM EST /9 AM CST/ this morning to 1 PM
     EST /noon CST/ this afternoon for LSZ162-241-242-263.

  Storm Warning from 1 PM EST /noon CST/ this afternoon to 4 AM
     EST /3 AM CST/ Thursday for LSZ162-241-242-263.

  Heavy Freezing Spray Warning from 1 PM EST /noon CST/ this
     afternoon to 7 AM EST /6 AM CST/ Thursday for LSZ162-
     240>242-263.

  Gale Warning from 10 AM EST /9 AM CST/ this morning to 7 AM
     EST /6 AM CST/ Thursday for LSZ240.

  Gale Warning from 10 AM this morning to 7 PM EST this evening
     for LSZ243-244-264.

  Heavy Freezing Spray Warning from 4 PM this afternoon to 7 AM
     EST Thursday for LSZ243-244-264.

  Storm Warning from 7 PM this evening to 7 AM EST Thursday for
     LSZ243>246-249-250-264>266.

  Gale Warning from 1 PM this afternoon to 7 PM EST this evening
     for LSZ245-246-265.

  Heavy Freezing Spray Warning from 7 PM this evening to 7 AM
     EST Thursday for LSZ245>248-265-266.

  Gale Warning from 1 PM this afternoon to 10 AM EST Thursday
     for LSZ247-248.

  Gale Warning from 2 PM this afternoon to 7 PM EST this evening
     for LSZ249-250-266.

Lake Michigan...
  Gale Warning from 4 PM this afternoon to 1 PM EST Thursday for
     LMZ221-248-250.

&&

SHORT TERM...TDUD
LONG TERM...Jablonski
AVIATION...LC
MARINE...Jablonski

Hazardous Weather Outlook
National Weather Service Marquette MI
522 AM EST Wed Dec 4 2024

MIZ001>007-009>014-084-085-051030-
Keweenaw-Ontonagon-Northern Houghton-Baraga-Marquette-Alger-Luce-
Gogebic-Iron-Dickinson-Menominee-Delta-Southern Schoolcraft-
Southern Houghton-Northern Schoolcraft-
522 AM EST Wed Dec 4 2024 /422 AM CST Wed Dec 4 2024/

This Hazardous Weather Outlook is for portions of central Upper
Michigan and western Upper Michigan.

.DAY ONE...Today and Tonight

Moderate to heavy lake effect snow expected today and tonight.
This combined with west-northwest winds gusting to 40 mph will
lead to blowing snow/reduced visibilities as well as wind chills
in the single digits above and below zero. See the latest Winter
Weather Warnings and Advisories for additional information.

Minor lakeshore flooding and beach erosion will be possible today
through tonight along the shorelines of Marquette, Alger, and
Luce Counties and across the west from Ontonagon through the
Keweenaw.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Moderate to heavy lake effect snow will continue through
Thursday. Blustery winds may lead to blowing snow, as well as wind
chills in the single digits above and below zero. See the latest
Winter Weather Warnings and Advisories for additional
information.

Minor lakeshore flooding and beach erosion will be possible into
Thursday along the shorelines of Marquette, Alger, and Luce
Counties and across the west from Ontonagon through the Keweenaw.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to submit snowfall reports to the National
Weather Service via phone, on our website, or through Facebook or
Twitter.

LSZ162-240>251-263>267-051030-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-Saxon Harbor WI to Black River MI-
Black River to Ontonagon MI-
Ontonagon to Upper Entrance of Portage Canal MI-
Upper Entrance of Portage Canal to Eagle River MI-
Eagle River to Manitou Island MI-
Manitou Island to Point Isabelle MI-
Point Isabelle to Lower Entrance of Portage Canal MI-
Lower Entrance of Portage Canal To Huron Islands MI Including
Keweenaw and Huron Bays-Huron Islands to Marquette MI-
Marquette to Munising MI-Munising to Grand Marais MI-
Grand Marais to Whitefish Point MI-
Lake Superior from Saxon Harbor WI to Upper Entrance to Portage
Canal MI 5NM off shore to the US/Canadian border including Isle
Royale National Park-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
Lake Superior East of a line from Manitou Island to Marquette MI
and West of a line from Grand Marais MI to the US/Canadian Border
Beyond 5NM from shore-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
522 AM EST Wed Dec 4 2024 /422 AM CST Wed Dec 4 2024/

This Hazardous Weather Outlook is for portions of Central Lake
Superior...Eastern Lake Superior and Western Lake Superior.

.DAY ONE...Today and Tonight

Northwest storm-force gusts to 50 knots are expected late
today through tonight. Heavy freezing spray is also possible. See
the Open Lake Forecast and Marine Weather Message for more
information.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Northwest storm-force gusts to 50 knots are expected through
Thursday. Heavy freezing spray is also possible. See the Open Lake
Forecast and Marine Weather Message for more information.

.SPOTTER INFORMATION STATEMENT...

The need for weather spotter reports is not anticipated at this
time.

LMZ221-248-250-051030-
Green Bay North of line from Cedar River MI to Rock Island
Passage-Seul Choix Point to Point Detour MI-
5NM East of a line from Fairport MI to Rock Island Passage-
522 AM EST Wed Dec 4 2024

This Hazardous Weather Outlook is for portions of Northern Lake
Michigan.

.DAY ONE...Today and Tonight

Northwest gales of 35 to 40 knots will be possible late today
through tonight. For more information, see the Nearshore Marine
Forecast and Marine Weather Message.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Northwest gales of 35 to 40 knots will be possible through Thursday.
For more information, see the Nearshore Marine Forecast and
Marine Weather Message.

.SPOTTER INFORMATION STATEMENT...

The need for weather spotter reports is not anticipated at this
time.

TDUD