Winter Storm in Michigan, December 4 to 6, 2024

Area Forecast Discussion
National Weather Service Gaylord MI
255 AM EST Wed Dec 4 2024

.KEY MESSAGES...

- Lake effect snow combined with gusty winds on the backside of
  a clipper system will bring about continued higher end travel
  impacts to the snowbelt areas of northwest lower and eastern
  upper Michigan.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 255 AM EST Wed Dec 4 2024

...More accumulating snow along with windy conditions on the way...

Widespread synoptic snow has developed across our entire CWA early
this morning well in advance of the approaching strong clipper
system...which is now centered over Western Ontario. Dominant SW
flow lake enhanced snow band embedded within the synoptic snow
shield continues to stream into the Straits area as expected...
dumping warning criteria snowfall from Leelanau county thru Western
Charlevoix to Emmet and Cheboygan and across portions of Eastern
Upper Michigan. All of the above areas are under a Winter Storm
Warning thru today and into early this evening....where 5 to 10
inches of new snow is expected.

Little will change during the morning hours as low level SW flow
persists...targeting the above outline areas withing the Straits for
the most persistent and heaviest snow shower activity. Total morning
new snowfall will be 5 to 10 inches within this area...and will
therefore leave all Winter Storm Warnings in tact. Rest of our CWA
will see light to at times moderate snowfall thru the morning...with
a general 1-3 inches of new snow expected. Winds gusting to 30 mph
will cause areas of blowing and drifting snow as well.

Initial cold front associated with the clipper system will sweep
thru our CWA this afternoon into early evening...shifting low level
flow to the NW. CAA will commence behind the initial cold front...
reinforcing ongoing over-lake instability and thus lake snow
production...but will refocus the most persistent and heaviest snow
showers into our typical NW flow snowbelt areas. A secondary cold
front will drop thru our CWA late tonight...shifting winds to a more
N/NW direction...which will likely shift the focus for heaviest
snowfall to areas along and west of US-131. Very tight pressure
gradient behind both the initial and the secondary cold front will
translate to winds gusting to 30 to 40 mph at times...producing
areas of blow and drifting snow and certainly hazardous travel this
afternoon thru tonight. All in all...expect new snow amounts for our
NW flow snowbelt areas of 5 to 10 inches this afternoon thru
tonight. Will therefore issue Winter Storm Warnings for all counties
along and west of I-75...and Winter Wx Advisories for much of NE
Lower Michigan where 3 to 5 inches of new snow along with blowing/
drifting snow is expected thru tonight.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 255 AM EST Wed Dec 4 2024

Pattern Synopsis / Forecast:

Clipper system will be exiting the region through the day on
Thursday, though with continued overlake instability and lingering
strong NNW flow, lake effect snows will be continuing across parts
of the region. Eventually, as the surface low moves east and surface
high pressure intrudes into the Corn Belt, the pressure gradient
slackens, thus reducing flow over the lakes, and more importantly,
diminishes available moisture to produce efficient lake effect snows
Thursday night into Friday. The influence of the surface high
pressure will keep things a bit drier (with some continued lighter
lake effect Friday), but on its heels, another clipper system will
be moving toward the Great Lakes, which looks to pass through Friday
night into Saturday, and another into Saturday night. The colder
pattern then moderates owing to the influence of a progressively
more northerly clipper track with these systems, drawing in warmer
air by the end of the weekend. Eventually, a baroclinic zone looks
to set up next week, but with ample uncertainty to the evolution of
any potential systems moving into the region.

Primary Forecast Concerns:

At the start of the period, efficient NNW flow lake effect snows
will be ongoing, with the most efficient region being spots downwind
of Grand Traverse Bay, which could see an additional 3-6"+ of
accumulation through the day Thursday. Elsewhere, perhaps an
additional few inches will be possible (lesser chances of additional
snow closer to Saginaw Bay and east of I-75 in the eastern U.P.).
The issue with Thursday will be focused on winds in other areas.
There will be ample fresh, fluffy snow that will be primed to be
blown around by those continued 15-25mph sustained winds, and gusts
of 30-45mph (locally higher near Lake Michigan), especially during
the morning hours when the strongest cold air advection overhead
supports efficient mixing and momentum transfer across the region.
Result will be continued snarled travel at the very minimum for the
Thursday morning commute across the snowbelts and other areas that
have snow cover to be blown around... with the snowbelts likely
seeing continued dangerous travel conditions Thursday due to
whiteouts and drifting snow, especially in open areas. Eventually,
the flow weakens later in the day into the overnight hours Thursday,
which should lower lake effect intensity, and confine it well
within those snowbelts.

Additional lake effect snows will be possible Friday as winds back
more westerly, shifting the focus of lake effect (albeit, a rather
lighter intensity) to the W to WNW flow snowbelts, though at this
juncture, there isn't much of a signal for more than a couple
additional inches through the day Friday. Eventually, a second
clipper passes through Friday night, and shifts winds more
southwesterly, which could put more lake effect into the Straits. As
of now, this system does not appear to be as intense as the one
passing through over the next 24-48 hours, but nonetheless, will
still be able to produce snow for the Straits and the eastern Yoop
as synoptic snows build in there, while most places south of M-72
hold drier. Furthermore, as milder air is drawn in by these systems,
it is possible for immediate lakeshore areas to see rain mix in at
times Saturday night into Sunday. Looking into next week, the
pattern is prime for a larger southern stream system (as opposed to
a clipper) to pass through from the southwest, and with milder air
in place, may lead to p-type issues. At this time, guidance is
signaling it as a warmer system with rain potential as temps raise
into the 40s. Eventually colder air is set to build in behind this
system, but uncertainty remains on how quickly that occurs... though
signals do indicate the milder temperatures should take a reprieve
around or slightly before midweek.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1147 PM EST Tue Dec 3 2024

Clipper low pressure system will bring increasing coverage/
intensity of SHSN overnight. PLN/CIU will the worst of it
tonight, becoming IFR to LIFR at times. TVC/MBL become IFR by
late tonight, APN becomes IFR Wednesday. Snow-liquid ratios in
the mid teens.

Sw winds become quite gusty tonight, veering w and wnw by late
Wednesday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Warning until 7 PM EST this evening for MIZ016-
     017-087-088-096-097.
     Winter Weather Advisory until 7 PM EST this evening for MIZ018-
     023-024-029-030-035.
     Winter Storm Warning until 7 PM EST Thursday for MIZ020-086-
     095-098-099.
     Winter Storm Warning until 7 PM EST Thursday for MIZ021-022-
     025>028-031>034.
MARINE...Gale Warning until 7 PM EST Thursday for LHZ345.
     Gale Warning from 10 PM this evening to 7 PM EST Thursday for
     LHZ346>349.
     Gale Warning until 7 PM EST Thursday for LMZ323-341-342-
     344>346.
     Gale Warning from 10 PM this evening to 7 PM EST Thursday for
     LSZ321-322.

&&

SHORT TERM...MLR
LONG TERM...HAD
AVIATION...JZ

Hazardous Weather Outlook
National Weather Service Gaylord MI
308 PM EST Tue Dec 3 2024

MIZ016>018-020>036-041-042-086>088-095>099-042015-
Emmet-Cheboygan-Presque Isle-Leelanau-Antrim-Otsego-Montmorency-
Alpena-Benzie-Grand Traverse-Kalkaska-Crawford-Oscoda-Alcona-
Manistee-Wexford-Missaukee-Roscommon-Ogemaw-Iosco-Gladwin-Arenac-
Western Chippewa-Central Chippewa-Southeast Chippewa-
Western Mackinac-Eastern Mackinac-
Mackinac Island/Bois Blanc Island-
Beaver Island and surrounding islands-Charlevoix-
308 PM EST Tue Dec 3 2024

This hazardous weather outlook is for Eastern Upper Michigan and
Northern Lower Michigan.

.DAY ONE...This afternoon and tonight.

Accumulating lake enhanced snow showers will refocus into the Straits
area tonight. Please see the latest Winter Storm Warnings for
additional details.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Accumulating lake enhanced snow showers will continue at times
through the rest of this week. Travel will be very difficult in
some areas downwind of Lake Superior and Lake Michigan. In
addition to the snow, gusty winds will create areas of blowing and
drifting snow with reduced visibilities. Whiteout conditions are
possible in some areas Wednesday night into Thursday. Please see
the latest Winter Storm Watches for additional details.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report snowfall amounts to the
National Weather Service. Reports may be made one of three ways:

Online:    weather.gov/gaylord
Facebook: facebook.com/nwsgaylord

Twitter:  twitter.com/nwsgaylord

For more information visit http://weather.gov/gaylord.

LHZ345>349-LMZ323-341-342-344>346-LSZ321-322-042015-
Straits of Mackinac within 5 nm of Mackinac Bridge including
Mackinac Island-St Ignace to False Detour Channel-
5NM East of Mackinac Bridge to Presque Isle Light MI including
Bois Blanc Island-
Presque Isle Light to Sturgeon Pt MI Including Thunder Bay
National Marine Sanctuary-Sturgeon Pt to Alabaster MI-
Grand Traverse Bay south of a line Grand Traverse Light to
Norwood MI-Seul Choix Point to 5NM West of Mackinac Bridge-
Norwood MI to 5NM West of Mackinac Bridge including Little
Traverse Bay-Sleeping Bear Point to Grand Traverse Light MI-
Point Betsie to Sleeping Bear Point MI-
Manistee to Point Betsie MI-
Whitefish Bay (U.S. Portion)/Whitefish Point to Point Iroquois MI-
St. Marys River Point Iroquois to E. Potagannissing Bay-
308 PM EST Tue Dec 3 2024

This hazardous weather outlook is for the northern Michigan
nearshore waters of Lake Huron, Lake Michigan and Lake Superior.

.DAY ONE...This afternoon and tonight.

Gale force wind gusts are expected to develop later tonight
across portions of Lake Michigan.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Gale force winds are expected across much of our nearshore waters
Wednesday into Thursday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

For more information visit http://weather.gov/gaylord.