FXUS63 KAPX 251612

Area Forecast Discussion
National Weather Service Gaylord MI
1112 AM EST Thu Feb 25 2021

Issued at 1112 AM EST Thu Feb 25 2021

Morning composite analysis reveals a subtle low level wave
traversing through the northern lakes region with an equally
subtle theta-e ridge nosing into northern Lower Michigan (sfc
dewpoints jumping into the 20s near the Michigan coast).
Warm advection, weak background forcing and marginal over water
instability is kicking off spotty synoptic and lake induced precip
across the region with a little heftier pocket of snow showers
sliding through eastern Upper Michigan per radar obs and webcams.

Low level wave and associated QG-forcing for ascent will kick on
through the region through the course of the afternoon and
continue to kick of spotty snow showers, particularly across
eastern Upper and NW Lower Michigan. Afternoon "heating" might
also add a small bit of convective contribution to the snow
showers this afternoon as well. In general, anticipate around half
an inch or less of accumulation where snow showers are most
persistent...perhaps a little better across parts of Chippewa
county and the SOO area given the heavier snow occurring up there
right now.


.NEAR TERM...(Today through Tonight)
Issued at 252 AM EST Thu Feb 25 2021

Impactful weather: Minimal. Scattered lake effect/enhanced and
diurnally-driven snow showers today.

Pattern synopsis and forecast:

Broad upper troughing stretched from the nrn Plains through the
Great Lakes early this morning, with a couple of weak perturbations
seen. One was dropping into western Lake Superior, and was
associated with a weak sfc circulation and trough that extends to
the SW. There were some patchy light system snow with these
features. The other was dropping into srn Manitoba, and was also
producing some patchy light snow. Here in nrn Michigan things were
pretty quiet. Skies were clear most areas, but in the coldest low
level air across eastern upper and NE lower, there were still some
lake clouds, which were also still producing a few flurries here and
there. The only other thing of note, is some increased mid level
clouds pushing toward our neck of the woods, ahead of the western
Lake Superior wave.

The aforementioned Lake Superior wave and associated weak sfc low,
will cross nrn Michigan today, followed by the second wave this
evening. Forcing from a deep layer -divQ standpoint was rather weak,
but a near marginal overlake instability environment coupled with
steep lapse rates of 7.5C/km from the sfc to the mid levels of the
atmosphere, is expected to fire off scattered morning lake enhanced
snow showers, with more diurnally-driven snow showers in the
afternoon. Could see some spots get a half inch of snow or so.

The second wave arrives this evening, and although hi-res guidance
is suggesting the marginal overlake instability and wave can fire
off some additional lake effect snow showers, believe the chance is
less than today. Only went for a slight chance, more into the higher
terrain, where maybe some orographic assistance can help. A few
tenths of an inch of snow at best.

Highs today will be in the low to mid 30s. Lows tonight may be
tricky. Readings will largely be in teens, with lower 20s around the
GTV Bay region. If the typically colder low lying areas of NE lower
can decouple (still some decent wind in the 950-925mb layer), maybe
some folks will get down into the single digits.


.SHORT TERM...(Friday through Saturday)
Issued at 252 AM EST Thu Feb 25 2021

...Above Normal, but Not Records...

High Impact Weather Potential...Minimal.

Pattern Synopsis/Forecast and possible impacts...Friday, 500 mb
ridge is over the Upper Great Lakes with the sfc ridge to the east,
which puts most of the forecast area in return flow. Temperatures at
this point look to be racing to around 10F above normal as the day
warms from the advection and the sunshine as the models show dry air
to support sunshine. Friday night, the clouds return and the next
system moves into the region. The P-type looks more like snow
overnight as the sfc temperatures fall below freezing, but as we get
into Saturday, and especially the afternoon, rain will mix in, with
the snow. The snow looks to be a bit on the spotty side with the GFS
idea, and the ECMWF idea is minor to light amounts. So will go with
the NBM (consensus) amounts 1-2" along and south of M-32, and less
than an inch north. Saturday afternoon looks like it will dry out as
the system moves out of the Upper Great Lakes. Part of the forecast
area looks like it could turn out partly or even mostly sunny. The
next system moves brings clouds into the region overnight into
Sunday morning.

.LONG TERM...(Saturday night through Wednesday)
Issued at 252 AM EST Thu Feb 25 2021

High Impact Weather Potential...Minimal at this point.

Extended (Sunday through Wednesday)...Models look like they are
backing off the timing of the onset of the precipitation. GFS and
ECMWF have the same basic idea by 18z/Sun with the bulk of the
precipitation moving up through W/C Upper, glancing off NW Lower,
and E Upper. After the system moves NE of the Upper Great Lakes,
Monday, the NW winds then bring 850 mb temperatures down to -16 to
-20C depending on the model. Will probably have some LES in E Upper.
The air looks dry, mainly on the GFS. While the ECMWF has moisture,
but 850 mb temperatures over N Lake Michigan are much warmer. So
maybe? The ridge pushes into the region by 00z/Tue, Consensus (NBM)
is dry, into Wednesday. 00z models (GFS and ECMWF) have a warm front
(different timings, but close enough) for some concern for
precipitation that will have to be dealt with in upcoming forecast
packages. However, Wednesday should be dry.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 521 AM EST Thu Feb 25 2021

An area of weak low pressure drifts down into the region today,
while high pressure will be drifting across the srn Great Lakes
tonight. The arrival of the weak low pressure will bring increased
cloudiness, along with scattered lake effect/enhanced and diurnal
snow showers. Conditions will primarily be VFR, but periods of
MVFR CIGS and of course reduced VSBYS, mainly with any snow
shower, is expected today for PLN/APN. Skies expected to at least
partially clear through tonight, with only a minimal threat for
MVFR CIGS at the NW lower airports.

SW winds will turn more out of the west this afternoon with some
gustiness at TVC/MBL. Winds lighten up and back out of the SW


Issued at 252 AM EST Thu Feb 25 2021

An area of weak low pressure drifts down into the region today,
while high pressure will be drifting across the srn Great Lakes
tonight. The pressure gradient will be more relaxed today and
tonight, allowing winds to drop below advisory levels in most
nearshores, but there could be some low end advisory gusts in the
Lake Michigan nearshores. A better shot at advisory gusts comes
Friday and Friday night ahead of another low pressure and cold
front, mainly for Lake Michigan nearshores.





NWS APX Office Area Forecast Discussion