Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 061135
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
635 AM EST Wed Dec 6 2023

.NEAR TERM...(Today through Tonight)
Issued at 330 AM EST Wed Dec 6 2023

High Impact Weather Potential...small. Lake effect snow
dwindling this morning. Light mixed precip tonight, mainly
eastern upper/ne lower MI.

High pressure extends from MO to southern James Bay. Just in
advance of this ridge, a mesolow is over far northern Lake MI.
Associated 1000-850mb convergence, in an axis that extends from
central upper MI into nw lower MI, has produced (as expected) an
uptick in lake effect snow coverage/intensity, especially in nw
lower. This axis also marks a subtle 850mb thermal trof (850mb
temps to -9C). However, looking upstream, activity is waning on
s central Lk Superior.

The mesolow should wash out thru the morning/midday hours today,
as the ridge axis presses eastward. Low-level flow will back sw
this afternoon, as we get behind the ridge. Low-level warm
advection develops and increases today. Will hang onto some
reasonable decent pops during the daylight morning hours,
especially from Petoskey to GLR and Kalkaska. Those pops wane by
midday. Maybe a few showers can push back into Leelanau/Benzie/
Manistee Cos this afternoon, as convergence increases near the
coastline in sw flow. Some spots in nw lower MI will pick up a
coating of snow, especially in the pre-dawn hours. Coverage/
intensity increases after that. Though precip will erode, clouds
are not expected to. In fact, low clouds should expand today
just beneath the strengthening inversion. Max temps today again
in the 30s.

Tonight, a fast-moving shortwave digs se-ward, just to the n
and e of Lk Superior. A surface warm front crosses northern MI
from w to e. There is a chance for early evening snow in the
north, mainly Chippewa Co. Pops increase tonight, mainly near
and north of a line from Petoskey to Harrisville. Highest
pops/QPF in eastern upper MI, closer to the better dynamics/
forcing. Progged QPF is less than 0.10", but is highest in far
eastern upper MI. Precip initially, and for the bulk of the
event, will be snow. Grids have up to an inch of snow in
central/eastern Chip Co (including the Sault), less elsewhere.
However, as warmer air aloft surges in, precip could become mixy
along its western flank, as the bulk of the precip is departing.
A transition to IP/ZR/RA is possible in spots before exits.
Again, the bulk of the precip will be snow, and do not expect
substantial impacts from any late mix. Mostly cloudy tonight,
though perhaps clouds decrease late in western Chip/Mack Cos.
Lows in the upper 20s to lower 30s, and relatively early;
readings will be climbing before dawn.

&&

.SHORT TERM...(Thursday through Friday)
Issued at 330 AM EST Wed Dec 6 2023

High Impact Weather Potential: Snowpack set to erode from abnormal
to potentially record warmth.

Pattern Synopsis: Digging trough ejecting from the Rockies will lead
to a ridging response over the eastern CONUS, resulting in anomalous
ridging overtaking the short term forecast period. 500mb heights set
to rise a general +1 sigma above climatological normal. This ridge
axis will build directly overhead by Friday, allowing for a subtle
but effective pressure gradient between a deep northern stream wave
progged to be over Minnesota and surface high pressure over the east
coast to become pinched with time, resulting in a deep southwesterly
flow over northern Michigan. This will draw in a markedly warmer
airmass with time that should reach its zenith through the day
Friday.

Primary Forecast Concerns: Thursday cloud cover; MaxTs both days

Lingering cloud cover from the departing WAA wing and associated
warm frontal passage (see near term) should gradually be on the
decrease form SW to NE through the day Thursday. Realistically, the
rising 500mb heights and presence of somewhat drier air should
result in a lack of sensible weather across the region. The big
question then becomes... where do temperatures in the wake of the
warm front lifting past the region? This is a rather tricky forecast
particularly for Thursday as the southwesterly flow will be a bit on
the weaker side given the pressure gradient won`t be entirely
pinched at this point. Regardless, it looks like widespread highs in
the 40s are possible across the CWA, with the warmer spot being
toward Saginaw Bay and west of US 131. In particular, it wouldn`t be
impossible for TVC, FKS, and MBL to have a sudden leap in
temperatures given the potential for clouds to clear earlier in the
afternoon during peak heating... so went a little more aggressive
there for temperatures... highs in the upper 40s to near 50. The
warm advection will carry into the overnight hours, and with flow
increasing, temperatures probably struggle to drop much Thursday
night. Completely possible for portions of NW lower to remain closer
to 40 overnight than the freezing mark, while most areas hover near
or perhaps slightly below 32 for the night. The warmth really shows
itself Friday, as the southwesterly flow kicks into gear, delivering
a more noticeable breeze across the region (S to SW winds 10-15mph,
gusts up to 25mph). One thing that could keep temperatures
(somewhat) in check will be increasing moisture in the upper
levels... and given that we are basically in the sun`s least
powerful time of year, that may help keep temperatures from
completely surging out of control. Regardless, looks like widespread
upper 40s to mid 50s are in the cards, with records at the short
period of record climate sites (GLR and PLN) potentially coming into
play. This warmth will likely deliver a knockout blow to the
snowpack across much of the CWA, with the most likely spots to
retain something through the short term period being the snowbelt
spots.

.LONG TERM...(Friday night through Tuesday)
Issued at 330 AM EST Wed Dec 6 2023

High Impact Weather Potential: Continuing to watch weekend system.

Ejecting wave in the Plains set to undergo surface cyclogenesis and
move into the Great Lakes region. Still a fair amount of uncertainty
for this setup regarding the exact track of the system... however,
the trends from the previous forecast cycle remain somewhat intact.
Thoughts regarding the potential of unsettled weather for the
weekend are coming more into focus. Current trends still favor
northern Michigan starting on the warmer end of the system as it
passes through the Great Lakes, though with colder air surging in
behind the system once it passes. How this system tracks will result
in various outcomes of precipitation types and intensity. A more
amplified and westerly solution (low passes over Lake Michigan)
probably puts us in the warmest possible outcome, with heavy rain
potential not out of the question given a closer proximity to deeper
moisture. A slightly weaker and more southeast track would probably
suppress precipitation potential, and perhaps a quicker and more
progressive passage through the region. Just looking at how guidance
is handling the cyclone, this has the look of a heavily occluded
system once it gets here, an outcome that guidance struggles with
considering its affinity for an amplified solution bias. Still tons
of details to iron out, but for now, it seems as though a weaker and
more southeast solution has a slight edge in the current outcomes.
Still going to hold off on messaging the system in exclusivity given
the uncertainties at this current forecast cycle. Should be noted
that the airmass int he wake of this system is set to be a bit
colder, and pending on how much synoptic moisture is left in the
tank, some lake effect processes may try to commence into early next
week, so that too may begin to need some monitoring in the coming
cycles as well.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 635 AM EST Wed Dec 6 2023

Mostly MVFR cigs today.

A ridge of high pressure is transiting the area. Lower clouds
will remain extensive today, though leftover snow showers and
flurries will diminish. MVFR cigs will be most common, though
VFR will occur at times, especially this afternoon and as you
head further south. Tonight, snow chances increase at CIU and
perhaps PLN/APN. Periods of IFR vsbys possible tonight at CIU.

Light winds will become w and sw. MBL will see winds become a
bit gusty late tonight.

&&

.MARINE...
Issued at 330 AM EST Wed Dec 6 2023

Winds will back w and sw today, as a ridge of high pressure
moves east across the area. Those winds increase late today into
tonight, and winds/waves will reach advisory levels on at least
Lake MI, and perhaps on some other waters as well. Will be
assessing marine headlines shortly, but do anticipate issuing
advisories for at least Lake MI soon.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
LH...Small Craft Advisory from 10 PM this evening to 10 AM EST
     Thursday for LHZ349.
LM...Small Craft Advisory from 7 PM this evening to 10 AM EST
     Thursday for LMZ323-341-342-344>346.
LS...None.
&&

$$

NEAR TERM...JZ
SHORT TERM...HAD
LONG TERM...HAD
AVIATION...J/Z
MARINE...JZ


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