FXUS63 KAPX 042300

Area Forecast Discussion
National Weather Service Gaylord MI
600 PM EST Mon Dec 4 2023

.NEAR TERM...(Through Tonight)
Issued at 305 PM EST Mon Dec 4 2023

High Impact Weather...None is expected.

Primary Forecast Concerns...Cloud cover, low temperatures and pops.

It continues to be a challenging cloud forecast across the region.
Just enough over lake instability to produce low clouds off of Lake
Michigan across the western half of the Northern Lower Peninsula.
This is expected to remain the case into tonight. In addition, an
Alberta Clipper which is expected to move by to our south Tuesday
will increase mid and high level moisture overnight. The combination
of this and the over lake instability may produce some light snow or
flurries across southwest zones...roughly from Manistee to Leland.
Elsewhere, clouds will be on the increase. Meanwhile across
eastern zones, mostly clear skies in combination with light winds
and a fresh snow pack will likely lead to excellent radiational
cooling conditions this evening (out ahead of the clouds). Wide
range of low temperatures expected tonight (will likely occur
early) with lows in the mid teens across eastern upper and
northeast lower while spots near Lake Michigan may only fall into
the low 30s.


.SHORT TERM...(Tuesday through Thursday)
Issued at 305 PM EST Mon Dec 4 2023

High Impact Weather Potential: Minimal.

Pattern Synopsis/Forecast: Broad long wave troughing encompassing
most of North America...strong upper low/trough over the northeast
Pacific directing an atmospheric river into British Columbia and the
Pacific northwest. Strongest flow well south of the Great Lakes...
with short wave troughs tracking across the Ohio/Tennessee Valleys
and digging southeast across the Dakotas. Low level thermal
troughing extends across much of eastern Canada and down into the
Great Lakes and New England (12z APX sounding 850mb temperature
was - 5C). At the surface several compact low pressure centers
reflective of their parent short waves aloft...one over western
Kentucky and a clipper over southern Saskatchewan (which is
lagging it parent short wave). Cyclonic flow lingers across the
Great Lakes in the wake of another low over the St. Lawrence River

Dakotas short wave trough will reinforce the mean long wave trough
position though the over pattern over North America becomes more
amplified.  By midweek the long wave trough wavelength shortens and
the axis shifts east as strong upper level ridging (+2 to +3 sigma
500mb height anomalies) expands across the Plains and into the
Midwest/Great Lakes.  This will eventually scour out the low level
thermal troughing in the Wednesday/Thursday time frame.  As that
occurs what remains of the current northeast Pacific low/trough will
send a couple of pieces of energy into the western U.S.  What comes
of that evolution will be discussed in the long term portion of this

Clipper low over southern Saskatchewan will follow its parent short
wave across the northern Plains and into the Ohio Valley Tuesday
(while continuing to weaken)...followed by high pressure that will
extend from the middle/lower Mississippi Valley northeast across the
Great Lakes Wednesday.  Warm air advection also kicks in Wednesday
around the north side of this anticyclone...continuing into

Primary Forecast Concerns: Snow coverage with clipper passing south
of the forecast area Tuesday...lake effect potential Tuesday night...
warm advection precipitation Wednesday night/Thursday...high
temperatures Thursday.

Snow coverage with clipper passing south of the forecast area
Tuesday: Surface low and short wave trough slicing by to the
southwest and south of the forecast area...there is a decent shield
of moisture around the north side of this system which spreads into
northern Lower...but better dynamic forcing expected to remain south
of the area and forecast soundings suggest incomplete saturation
between synoptic moisture and lingering boundary layer moisture
which will probably be enhanced a bit by instability off of Lake
Michigan.  So whether or not there will be an effective seeder-
feeder process or not is the question especially the farther north
you go.  Have leaned on SREF PoPs for this forecast which highlights
areas west of the US-131 corridor for better potential for
measurable precipitation with some shallow lake enhancement
possible...mostly snow but perhaps falling as rain along the
lakeshore with a shallow surface based warm layer.  Will also have
some flurries mentioned in most other areas.

Lake effect potential Tuesday night: Light north-northwest boundary
layer flow expected Tuesday night as surface ridging builds in from
the west.  Cold air continues to linger (850mb temperatures in the
-8C to -10C range)...and given the weak nature of the boundary layer
flow some lake breeze formation may focus convergence especially on
the Lake Michigan side where again will focus better SREF based

Warm advection precipitation Wednesday night/Thursday: Solid push of
warm air begins in earnest on Wednesday...band of Pacific moisture
interacting with this baroclinic zone expected to bring a relatively
narrow north-south oriented band of precipitation to northern
Michigan probably starting Wednesday evening.  Likely starting as
mostly snow but strength of warm advection may result in a change to
rain on the back end of the precip band (perhaps freezing rain in
the higher terrain where surface temperatures will be close to
freezing??).  Accumulations should be light (mostly likely under an

High temperatures Thursday: Looking at widespread 40s on Thursday...
how warm may depend on how soon cloud cover clears out of the
area. Most record highs are in the 50s save for ANJ (45/1951) and
PLN (47/1953).

.LONG TERM...(Thursday night through Monday)
Issued at 305 PM EST Mon Dec 4 2023

High Impact Weather Potential: Wintry weather potential for the
weekend...with lots of uncertainty however.

Pacific-origin height falls spreading across the western U.S.
starting Thursday will have a large impact on the extended forecast.
There may be a lead short wave trough the passes in the vicinity of
the upper Lakes Friday...while a larger amplitude trough develops
over central North America by next weekend.  Focus will be on the
base of this trough as it moves out of the southern Plains into the
lower Mississippi Valley Sunday into Monday.  At the very least
looks more unsettled through the weekend and also portends a return
of colder air to Michigan...but there are a number of uncertainties
in play with regard to system timing/strength.  That combined with
this being a day 6/7 type of event will preclude any messaging just
yet...will give the guidance a couple of days to simmer on this.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 600 PM EST Mon Dec 4 2023

Weak low level ridging currently in place across the Western
Great Lakes will give way to low pressure diving SE out of the
Northern Plains and into the Southern Great Lakes tonight...and
then into the Ohio Valley on Tuesday. Majority of precip from this
system will slide south of our area...but will give our SW CWA
(around TVC and MBL) small chances of light snow over the next 24
hours. Prevailing conditions will remain MVFR/low VFR thru Tuesday
night. Surface winds will remain generally light and from the


Issued at 305 PM EST Mon Dec 4 2023

Minimal marine issues expected through midweek with a weak
pressure gradient in place as high pressure eventually slides in
from the northwest on Wednesday. Winds will begin to pick up later
Wednesday into Wednesday night as the surface ridge axis slides
to the east...this may bring small craft conditions to at least
Lake Michigan nearshore zones Wednesday night.





NWS APX Office Area Forecast Discussion