000
FXUS63 KAPX 272316
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
616 PM EST Sat Nov 27 2021

.NEAR TERM...(Through Tonight)
Issued at 406 PM EST Sat Nov 27 2021

...One snow event ends, and another arrives...

High Impact Weather Potential: Moderate.

1008mb surface low is passing a bit north of ORD this afternoon,
with a warm front extending into ne IN and central OH. Isentropic
ascent and f-gen has pushed a band of -SN across much of northern
lower MI, further north than originally planned. Mid-level drying
has worked into the far sw, though cigs are quite high down there
and drizzle is not (yet) a player.

Original surface low will track toward western Lk Erie
overnight. Associated snow will gradually exit eastward this
evening. Will need to keep an eye out for DZ development, but the
window between systems is relatively small, and FZDZ on top of
fresh snow poses a relatively minor hazard.

A vigorous clipper shortwave will dig and close off, very near
MQT by Sunday morning. Surface wave (1006mb) reaches eastern
Superior. Deeper moisture floods back in the from north, with lake
enhanced snow returning from nw to se. Winds will be all over,
with an initial period of sw-flow enhancement off of Lake MI just
as precip gets going, before rapid veering to nw occurs toward
morning.

Snowfall amounts overnight range from 1-2" along the nw lower MI
coastal counties, highest up in Emmet. 1-3" across all of eastern
upper MI, highest in western Chip/Mack.

Given the snow amounts overnight and into Sunday, a winter wx
advis will be posted for western Chip/Mack.

Min temps low-mid 20s.

&&

.SHORT TERM...(Sunday through Tuesday)
Issued at 406 PM EST Sat Nov 27 2021

High Impact Weather Potential: Accumulating snow Sunday into Sunday
night...more snow Monday/Tuesday...

Pattern Synopsis/Forecast:

This morning`s surface analysis has a 1008mb low centered near
Minneapolis, associated with a weak shortwave aloft...embedded in
broader north-south oriented surface troughing that extends
northward to a second surface low in northern Manitoba (associated
with a stronger niblet of energy a little further north in Canada)
...and southwestward into the Desert Southwest, associated with a
southern stream closed low there. Low pressure system over New
England continues to depart eastward, with high pressure moving out
of the Great Lakes as our next system moves in...and high pressure
across the western US, bridging a cold front that extends westward
from the Minneapolis surface low back up into the Canadian
Rockies...in advance of the next system moving onto the West Coast
attm.

Going into Sunday morning...that northern shortwave, associated with
the surface low in Manitoba today...will be diving into the northern
Great Lakes ahead of a 120+kt upper level jet max moving through the
flow...and riding over ridging across the western/central US.
Surface low should be for the most part vertically stacked as it
progresses southsoutheastward through the region. With cold air
aloft remaining in place...as well as reasonably moist mid-and-low
levels...will look for lake effect to take over for most of
Sunday...with accumulating snow in the typical northwest flow snow
belts. Similar to the situation we`ve experienced the past couple
days and are experiencing today...will look for high pressure to
return to the area later Sunday night into Monday (though it may
take some time to put a complete stop to lake effect)...with another
surface trough collocated with a warm front out west...bringing
another round of mid-level moisture to the region for Monday, and
perhaps into part of Tuesday as well, with another system quick on
its heels, too.

Primary Forecast Concerns: Snow Sunday into Sunday night...more snow
Monday and Tuesday...

Going into Sunday morning...will look for the surface cold front to
be crossing the CWA...perhaps more or less along US-131/I-75 by 12z.
Ahead of this feature...will expect good low level convergence as
winds switch from southerly to northwesterly...with additional lift
possible in the upper levels just ahead of the shortwave trough,
scraping our NE CWA. Both mid and low level moisture remain ample
along and behind the front...with 850-700mb RHs greater than 70%
across much of the CWA through the period. Though 850mb temps are a
bit warmer (still sufficient for overlake instability, however, at -
7 to -8C or so), we should remain saturated through the DGZ. Some
model soundings suggest we may stay deeply saturated up to 3km or
greater...which would indeed be much more impressive than the last
lake effect event, if it comes to fruition. NW flow behind the cold
front will ramp up, as a tighter pressure gradient on the backside
of the system slides through...suggesting that we may see lake bands
penetrate further inland, as well as potential for better moisture
flux off the lakes...though the stronger winds may fracture
snowflakes and diminish snow-to-liquid ratios (i.e., the snow will
stack up...but just how fast/much it will stack up is a little
uncertain).

All this being said...will look for a potentially more intense band
of snow along/ahead of the cold front as it passes through the CWA
Sunday morning...with a quick switchover to northwest flow lake
effect behind it. With decent looking parameters Sunday...lake
effect accumulations, and perhaps total snow accumulations overall
(including the pre-frontal band), will be more impressive than the
Thanksgiving night-Friday evening. Better mid-level moisture should
begin to depart Sunday night ahead of colder 850mb temps aloft as
high pressure scoots into the region...suggesting that we may not
completely shut off the lake machine Sunday night, but we will have
to keep an eye on things as lingering lake processes could produce
light precipitation despite things drying out aloft. May have to
watch for some patches of freezing drizzle...? Will leave it out of
the forecast again, given some uncertainty...and will again let the
mid shift reassess.

Will look for only a short break in the action for early Monday...as
mid-level moisture returns Monday in combination with additional
upper-level divergence ahead of the next system sliding in from the
west. Similar to the system we`re currently experiencing...there is
still some uncertainty in the exact track and position of this
system and where exactly the heaviest snow will end up...though
guidance is perhaps starting to get a better handle on it. Precip
could start as early as Monday afternoon across the area...with
perhaps the heaviest precip moving through during the late afternoon
into the overnight. This will be another synoptic, warm advection
type setup ahead of a surface low...so will look for more widespread
snow...with potential lake effect behind it as winds turn more
westerly again...and 850mb temps remaining sufficient to keep
overlake instability going. Lake effect potential and placement will
ultimately depend on wind direction...and how deep the moisture
remains behind the system. Another potential cold front dropping in
later Tuesday may lead to an uptick in precipitation potential yet
again...though this doesn`t look particularly impressive attm.

.LONG TERM...(Tuesday night through Saturday)
Issued at 406 PM EST Sat Nov 27 2021

High Impact Weather Potential: Minimal attm...

Pattern Synopsis/Forecast:

Going beyond Tuesday night...active weather looks to remain the
overall idea through the rest of the week...as an upper level jet
max progresses through the flow onto the West Coast...potentially
helping to deepen troughing across the central US. Will have to keep
an eye on the track and timing of this...as it will determine things
like...how warm it gets ahead of the system for midweek, how much
precip we get, what precip type, and potential for lake effect
behind it, to name a few. Guidance beyond this becomes increasingly
uncertain, given lack of run-to-run consistency...but the overall
idea of active weather seems to remain in play going forward into
the month of December.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 616 PM EST Sat Nov 27 2021

Low pressure will continue to make its way thru the Great Lakes
region over the next 24 hours...generating areas of snow for much
of Northern Lower Michigan. Sufficiently cold air combined with
low level winds shifting to the NW on Sunday will provide lake
enhancement to this ongoing synoptic snow event. Overall
conditions will remain MVFR/IFR thru Sunday evening. Light/calm
winds tonight will become NW and strengthen to 15 to 25 kts on
Sunday...with some higher gusts possible across NW Lower Michigan.

&&

.MARINE...
Issued at 406 PM EST Sat Nov 27 2021

Weaker low pressure will transit far southern lower MI tonight. A
stronger low will drop in from the nnw, crossing eastern upper MI
Sun morning. Gusty nw winds kick in behind that low, and small
craft advisories are likely on most of our waters.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY from midnight tonight to 4 PM EST Sunday
     for MIZ086-095.
LH...SMALL CRAFT ADVISORY from 10 AM Sunday to 1 AM EST Monday for
     LHZ345-349.
LM...SMALL CRAFT ADVISORY from 4 AM Sunday to 1 AM EST Monday for
     LMZ323-341-342-344>346.
LS...SMALL CRAFT ADVISORY from 10 AM Sunday to 1 AM EST Monday for
     LSZ321.
&&

$$

NEAR TERM...JZ
SHORT TERM...FEF
LONG TERM...FEF
AVIATION...MR
MARINE...JZ

NWS APX Office Area Forecast Discussion