000
FXUS63 KAPX 281432
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
932 AM EST Tue Nov 28 2023

.UPDATE...
Issued at 911 AM EST Tue Nov 28 2023

Not much to change to inherited forecast. Fairly well organized
lake bands continue to impact the snowbelt locations this morning.
Flow is decidedly northwest...bringing the best snows into
northwest lower Michigan. Transit pockets of one inch per hour
snowfall rates within these bands, no doubt resulting in at least
a few inches of additional accumulations where bands have been
most persistent.

Expect lake processes to significantly throttle back as we head
through this afternoon with quickly backing winds, agressive
drying through the boundary layer, and lowering convective cloud
depths (all a result of impinging surface ridge axis). Still
looking at few more inches under those most persistent bands
before this downward trend begins. All headline end times will
remain.

&&

.NEAR TERM...(Today through Tonight)
Issued at 421 AM EST Tue Nov 28 2023

Key Messages:

- Accumulating lake effect snow will continue across NW lower and
  the eastern U.P. today with medium to high chances (40 to 70+
  percent) for an additional 4 inches for localized areas.

- A lull in snow intensity and coverage is expected later this
  afternoon and evening.

- Additional accumulating snow is anticipated tonight into Wednesday
  morning with medium to high chances (40-70+ percent) for another 2
  inches of snow across NW   lower and the eastern U.P.

Pattern Synopsis:

Deep troughing will continue to pivot across southeast Canada/Great
Lakes region as an associated surface cyclone treks northeastward
across Quebec today. An attendant weak front looks to sag from north
to south across northern Michigan this morning, eventually being
pushed eastward as low-level ridging temporarily slides overhead
this afternoon and evening. A shortwave embedded in the main flow
looks to dig across the upper Midwest and overhead tonight,
providing sufficient forcing aloft to support a weak cyclone that
will move into Ontario/Hudson Bay with a seconds front swinging into
the Great Lakes by Wednesday morning.

Forecast Details:

As stated in the key messages, accumulating lake effect snow will
continue across parts of NW lower and eastern upper Michigan this
morning into this afternoon. Forecast soundings display a favorable
environment to support moderate to heavy snowfall rates within lake
effect bands into this morning -- which has already been seen
tonight at KCIU with heavy snow and visibilities dropping to 1/4
mile or less for over an hour as a concentrated band set up over the
site. Wind direction across eastern upper and parts of northwest
lower are expected to turn slightly more northwesterly with time
through this morning as aforementioned surface ridging works into
the region.

With this said, strongest banding is expected to focus across Antrim
and Kalkaska counties through this morning, bringing high chances
(greater than 70 percent) for an additional 4 inches of snow into
early afternoon -- and even low chances (10-40 percent) for
localized areas to see an additional 8" or more. Other portions of
NW lower are expected to see a few more inches of additional
snowfall during that time, most likely across the typical northwest
snowbelts of northern lower and eastern upper. Drops to a quarter
mile visibility will be possible underneath strongest lake effect
bands, and wind gusts of 15-25 mph may lead to some blowing and
drifting at times this morning with dry snowfall (SLRs close to
20:1). The combination of drops in visibility and snow-covered
roadways will lead to hazardous travel across parts of the area this
morning.

After a lull in snow intensity and coverage this afternoon and
evening, accumulating snow chances will return along/ahead of the
aformentioned front tonight. Forecast soundings display an
appreciable portion of the saturated low/mid-level profile
collocated within the DGZ, which will likely lead to efficient snow
crystal growth and thereby efficient snowfall. Medium-high chances
(40-70 percent or greater) exist for an additional 2 inches across
much of NW lower and eastern upper Michigan, with some areas near
Little Traverse Bay most likely to see totals near 4 inches.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 421 AM EST Tue Nov 28 2023

HIGH IMPACT WEATHER POTENTIAL: Low for now...periodic light snow
and/or drizzle/freezing drizzle.

PATTERN SYNOPSIS/FORECAST:

Longwave troughing still holding steady over the eastern continent.
Positively tilted shortwave trough axis about to swing through the
Upper Great Lakes as of 3z/28...as lake effect continues amid sub -
12C 850mb air crossing the region. Ridging remains firm over the
western US...with strong northerly flow largely encompassing the
central US/MS valley...deforming into a confluence zone over the SE
US, where 160+kt zonal-ish upper level jet hangs on...keeping most
of the moisture out of the CONUS. Clipper system trekking over the
ridge into the central Canadian Prairies, with a surface reflection
extending from Saskatchewan down into the Mid MS Valley; strong
height rises on warm advection ahead of this feature over Manitoba
into the Upper Midwest.

Shortwave trough axis exits eastward today...but height rises in its
wake will be short-lived...as next clipper system rides the flow
down into the Great Lakes tonight into Wednesday. Do think a surface
boundary will swing through our area Wednesday morning...though it
looks like the boundary will hang on back to the NW behind this...as
additional energy digs into the western US. Suspect we may not be
entirely quiet Wednesday night into Thursday...as this energy digs
across Canada and develops a surface low to our north going into
Thursday. Signals point toward the system crossing the region later
Thursday into Thursday night, although there are still a few minor
timing differences to contend with.

Primary Forecast Concerns:  Periods of snow/freezing drizzle...

Main vort max should be on its way out Wednesday morning, though
some energy lingering over the area should keep things active,
particularly over the usual snowbelts. Mean cloud flow looks to
shift from NW/WNW early toward more W by late in the day...with
guidance currently pointing toward more favorable inversion heights
(maybe 6kft) up across the EUP where there will be better fetch off
southern Lake Superior...and think this is where the bulk of the
snow will fall in the afternoon. Moisture stripping out further
south over NW Lower suggests drizzle/freezing drizzle could become a
concern, as inversion heights plummet and cloud top temperatures
warm to -5C or so, diminishing ice nucleation potential.

Thursday could be a bit tricky...as guidance points toward potential
for a lack of moisture early in the day, increasing with time as
that system takes shape to our northwest...and as better forcing
approaches. Think that W/SW flow areas would be more favored, with
lower SLRs as the profile should be warmer...though again, can`t
rule out the freezing drizzle potential, either...particularly if
this system ends up coming through when surface temps are below
freezing (i.e., Thursday night). Main focus should again be the EUP
closer to the system, though not impossible that parts of Northern
Lower could be affected, particularly if the approaching southern
stream system is able to give a boost to forcing...and if it is
further north (which is more likely if the Thursday system zips
through quicker).

.LONG TERM...(Thursday night through Monday)
Issued at 421 AM EST Tue Nov 28 2023

HIGH IMPACT WEATHER POTENTIAL: Minimal for now...

PATTERN SYNOPSIS/FORECAST:

Aforementioned trough should be on its way out Friday, lingering a
SW-NE oriented BCZ into the southern Plains, along which a southern
stream disturbance looks to ride. Think the bulk of the impacts from
this will be well south of our area, assuming the current idea
holds...though it`s not impossible that warm advection could bring
some precip into our area...and will have to watch for lake
convection in the meantime, with the northern stream trough nearby.
Not impossible there could be another weak disturbance Friday
night...though the bigger story will be troughing digging over the
western US going into the weekend. While this does signal potential
for milder weather here in the Great Lakes...do think warm advection
concerns will come into play as bits of energy eject northeastward
along the flow toward the Upper Midwest this weekend. Still working
on timing out these bits of energy for Sunday into Monday and
beyond, though it appears the overall trough axis will slip overhead
as we go into Monday night. Think it will remain at least nuisance-y
active here in the Great Lakes into the start of next week...with
potential for lake effect to return going into the end of the
extended and beyond, depending on how long the upper trough hangs
around. With the potential for milder air and warm advection...will
be keeping an eye out for this active period to also be a little
more mixy/rainy than what`s going on out the window right now.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 629 AM EST Tue Nov 28 2023

Lake effect snow showers will continue across northwest lower and
eastern upper Michigan into this afternoon, creating variable VSBY
conditions at northern Michigan TAF sites -- with most likely drops
to MVFR/IFR conditions at CIU and TVC over the next several hours.
MVFR CIGs will also hold across parts of northern Michigan before
they are expected to lift to VFR later this afternoon as low levels
dry out and snow shower coverage/intensity wanes. Additional snow
will return to northern Michigan later tonight, along with drops
to MVFR/IFR conditions for most sites. Otherwise, gusty northwest
winds will gradually turn to southwest winds by this evening.


&&

.MARINE...
Issued at 421 AM EST Tue Nov 28 2023

Small craft advisory winds and waves are expected to continue across
northern Great Lakes nearshore waters through tonight.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 11 AM EST this morning for MIZ016-
     017-020-025-026-031-032.
     Winter Weather Advisory until 1 PM EST this afternoon for MIZ021-
     022-027-028-086-087-099.
LH...Small Craft Advisory until 7 AM EST Wednesday for LHZ345>349.
LM...Small Craft Advisory until 7 AM EST Wednesday for LMZ323-341-342-
     344>346.
LS...Small Craft Advisory until 7 PM EST this evening for LSZ321-322.
&&

$$

UPDATE...MSB
NEAR TERM...DJC
SHORT TERM...FEF
LONG TERM...FEF
AVIATION...DJC
MARINE...DJC