700
FXUS63 KAPX 042058
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
358 PM EST Thu Dec 4 2025

.KEY MESSAGES...

- Light snow tonight with some lake enhancement in southwest flow
off Lake Michigan...round 1.

- More widespread snow Friday night with (maybe) some lake
enhancement off Lake Michigan...round 2.

- Windy and colder Saturday with lake effect snow showers returning.

- Another round of synoptic snowfall in the Sunday time frame.

- Alberta clipper around Tuesday? Maybe...

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 358 PM EST Thu Dec 4 2025

Pattern Synopsis/Forecast: Full latitude long wave trough
encompasses North America this afternoon...some impressive 500mb
height/temperature anomalies within the core of the trough over
Ontario/Quebec (-2 to -3 sigma standardized height anomalies/-48C
with the thermal trough).  Large scale pattern is amplified all the
way across the Pacific Basin...with -EPO ridging over the eastern
Pacific.  But things are shifting...trough axis is east of the upper
Lakes this afternoon as a strong PV anomaly (dynamic tropopause
below 600mb) rotates across southern Ontario/Quebec with height
rises just upstream.  Mid level warm advection already underway
across the upper Midwest and spreading into Wisconsin/ Michigan...
ahead of another short wave trough digging southeast out of Manitoba
(better defined at 700mb).

Surface analysis shows a 1035mb high centered over Iowa...in the wake
of yesterday`s cold front passage.  Sharp mesoscale troughing runs
southeast/northwest across Lake Huron/Lake Superior due to lake
heating.  Surface cold air was "horseshoeing" around the upper
Lakes...but an impressive textbook example of cold air draining off
the higher terrain east of Lake Superior and into eastern Upper
earlier this morning.  Winds at CYAM were gusting to 43kts from the
northwest before the wind flipped to northeast and the temperature
dropped 9F.  So even against that background flow the density current
was able to overcome that and dropped all the way into northern Lake
Huron.

Surface high over Iowa slides south of Michigan this evening...
swinging boundary layer winds to the southwest while upstream short
wave trough crosses Lake Superior during the early morning hours.
This will be followed by another short wave trough tracking farther
south than the previous one...arriving Friday night and pushing a
cold front across Michigan that will bring a renewed shot of cold
air for the weekend.

Primary Forecast Concerns:

Light snow tonight with some lake enhancement in southwest flow off
Lake Michigan...round 1: Backing low level winds already underway
this afternoon...which will push existing multiband convection east
and northeast and should get some southwest flow bands going on
northern Lake Michigan.  These look to be relatively shallow to
start but the cloud layer is within the DGZ thermal range with an
inversion height around 800mb.  Most of this activity should be
focused into eastern Upper and the tip of the mitt.  Isentropic
ascent will spread mid/high level moisture across roughly the
northern half of the forecast area this evening...but there is a dry
layer between the higher level clouds and the top of the CBL.  So
initially there won`t be seeder-feeder enhancement...but the column
is expected to moisten after midnight and some increase in low level
convergence which may be a signal of a more dominant band getting
organized.  Anticipating a boost in snow intensity into eastern
Upper and the Straits region overnight and into Friday morning.
Eventually looks like a band of snow will propagate southward across
northern Lower Friday (more on this below).

So for snow amounts in the enhanced areas do think that parts of the
eastern Upper plus Emmet county zones are going to be pushing
advisory criteria snowfall amounts (in the 3-6 inch range roughly
from midnight to noon).  Far northern Cheboygan county and westerly
Mackinac county will be close...but snowfall won`t be the only issue
with increasing southwest winds tonight.  Wind gusts of 30 to 40mph
are likely...so blowing and drifting snow will just add to the
impact (the drive along US-2 might not be much fun overnight).  Will
go ahead and hoist a Winter Weather Advisory for the zones mentioned
above (plus the islands)...will include Cheboygan county to avoid
getting to cute though it may not get "bad" there until late tonight.

More widespread snow Friday night with (maybe) some lake enhancement
off Lake Michigan...round 2: Approach of next short wave trough
Friday afternoon is expected to result in an increase in snowfall
coverage across northern Michigan.  Good dynamic forcing and steep
mid level lapse rates could surprise a bit from a synoptic QPF
standpoint.  But will see about the details of that...mid level
moisture may strip away overnight ahead of the cold front passage
(so maybe end with a period of freezing drizzle??).  Not as great a
lake enhancement signal off Lake Michigan Friday night but it is
still there and certainly won`t hurt the cause; shallow CBL mostly
at temperatures warmer than -10C may just add a lot more supercooled
droplets and riming potential to the equation...which would cut down
on SLR.  But certainly several more inches of snow in the cards for
eastern Upper/northwest Lower through 1200Z Saturday.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 358 PM EST Thu Dec 4 2025

Primary Forecast Concerns:

Windy and colder Saturday with lake effect snow showers returning:
Gusty northwest winds will bring colder air into Michigan Saturday
in the wake of a morning cold frontal passage.  Does not look overly
impactful at this point (other than the fact that it won`t stop
snowing).  Temperatures probably steady or falling through the 20s
Saturday.

Another round of synoptic snowfall in the Sunday time frame: Another
short wave trough in the persistent northwest flow looks to arrive
Sunday and bring another round of widespread snow...followed by some
lake effect (again not looking overly impressive).  Another day of
highs in the 20s (normals this time of year are lower to mid 30s).

Alberta clipper around Tuesday?  Maybe...: Indications of such an
event but the details are all over the place.  But PoPs will be
increasing into the midweek period.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1258 PM EST Thu Dec 4 2025

Ongoing lake effect snow showers will dissipate this afternoon
continuing VFR conditions through this evening. Winds currently from
the NW will back to the SW tonight, becoming gusty overnight before
tapering through the day Friday. Additional -SN returns to KCIU and
KPLN tonight followed by lowering cloud cover, dropping CIG`s and
VISBY`s to MVFR around 0800-1400Z for all sites and continue to
lower beyond the end of the forecast period.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory from 11 PM this evening to 11 AM EST
     Friday for MIZ016-086>088-095-096-098.
     Winter Weather Advisory from 1 AM to 11 AM EST Friday for
     MIZ017.
MARINE...Gale Warning from 10 PM this evening to 11 AM EST Friday for
     LHZ345.
     Small Craft Advisory until 5 PM EST Friday for LHZ347-348.
     Small Craft Advisory until 5 AM EST Saturday for LHZ349.
     Gale Warning from 10 PM this evening to 11 AM EST Friday for
     LMZ323-341-342-344>346.
     Gale Warning from 11 PM this evening to 11 AM EST Friday for
     LSZ321.
     Small Craft Advisory from 11 PM this evening to 11 AM EST
     Saturday for LSZ322.

&&

$$

SHORT TERM...JPB
LONG TERM...JPB
AVIATION...SJC