FXUS63 KAPX 132050

Area Forecast Discussion
National Weather Service Gaylord MI
350 PM EST Thu Dec 13 2018

.NEAR TERM...(Through Tonight)
Issued at 347 PM EST Thu Dec 13 2018

...Wintry Mix Precipitation Tonight...

High Impact Weather Potential: Light snow/ice accumulations south,
some freezing drizzle north.

Pattern Synopsis/Forecast: Upper air analysis reveals a broad
ridge/trough/ridge pattern across the CONUS. Main upper jet takes a
deep dive from the northern Rockies down into the south-central
CONUS with a detaching mid level short-wave and low pressure closing
off over Texas. Weaker northern branch and short-wave trough is
progressing through the Upper Midwest. At the surface, low pressure
is over east Texas ahead of the aforementioned short-wave with a
surface trough that stretches northward through the Midwest. Most of
the active weather continues along the Gulf and into the mid
Mississippi River Valley but with deep moisture advection and precip
spreading north/northeastward ahead of the trough. Some very light
precip noted moving out of the Minnesota ahead of the northern
stream short-wave trough.

Across the CWA currently, lower cloud cover has stuck around in most
locations although some thinning/brightening has been seen around
the region. But nearly everyone has been able to warm to the middle
and upper 30s.

Primary Forecast Concerns/Challenges: Precip type, light icing and
light snow accumulations.

Northern stream short-wave will press across the northern lakes
region late tonight through Friday morning. QG-forcing for ascent is
rather unimpressive. But, this system will act to tighten/squeeze
the thermal gradient across lower Michigan with subsequent
development of a modest deformation axis bisecting lower Michigan.
Strongest response/highest pops-QPF expected to be through the
Saginaw Valley and points south...essentially along and south of the
M-55 corridor.

Precip type is another matter. Initially, forecast soundings across
my southern counties suggest primarily snow to start. But as low
level warm air gradually noses up into northern lower Michigan,
still think we see a transition toward more liquid/freezing rain
very late into Friday morning. Combination of light snow
accumulation and some light icing late may ultimately necessitate a
winter weather headline. But I`d prefer to allow evening or
overnight crew see how things evolve and make the call as needed
toward the morning commute.

Further north, just some light nuisance precip (light snow, patchy
freezing drizzle) anticipated along the track of the short-wave
trough. That said, any freezing drizzle could also necessitate and
winter weather headline in itself. So...again will allow later
shifts to see how things unfold.


.SHORT TERM...(Friday through Sunday)
Issued at 347 PM EST Thu Dec 13 2018

...Early precip threat Friday morning then a dry weekend...

High Impact Weather Potential: Wintry mix possible near Saginaw Bay
Friday morning.

Pattern Synopsis/Forecast: Split short wave trough moving across
central North America this afternoon...northern branch was moving
into the upper Midwest while a compact circulation in the southern
branch was over Texas.  Pattern upstream of this short wave is
amplifying....with broad ridging over the western U.S. and another
short wave trough approaching 140W.  Northern branch wave
(actually two pieces of energy) will lift across the Upper Lakes
Friday...while the southern branch will deepen as it bowling balls
its way along the Gulf Coast before turning northeast into the mid
Atlantic.  New amplifying eastern Pacific short wave trough will
push inland quickly this weekend...with some associated height falls
eventually reaching Michigan by Monday (along with a new push of
colder air across the Lakes to start next work week).

At the surface...1035mb high pressure over northern New England...
with some surface troughiness over northwest Ontario and the upper
Midwest associated with northern branch short wave trough.  Better
defined surface low was along the Texas/Oklahoma border with the
stronger upper support associated with the southern branch wave.
This surface low will remain south of Michigan while a narrow east-
west oriented high pressure ridge sets up across the state beneath
deformation/confluence axis between jet branches.  Approaching
height falls with Pacific short wave trough will push a cold front
across Michigan probably in the Sunday night time frame.

Primary Forecast Concerns: Only real concern in the short term is
lingering precipitation Friday morning across northeast Lower with
last lingering bit of deep moisture associated with isentropic
ascent.  Warming aloft and near freezing surface temperatures could
bring a mix of snow/liquid (rain or freezing rain depending on
surface temperatures) over the far southeast portion of the forecast
area near Saginaw Bay.  All of this looks to exit stage right Friday
morning...with a strong push of dry air in its wake as evident in
afternoon satellite imagery over the Dakotas/western Minnesota.
There is a second PV anomaly in the northern branch forecast to pass
north of Lake Superior Friday afternoon but doesn`t look to have
much impact on the forecast area.

Little in the way of forecast concerns beyond Friday afternoon
through Sunday with aforementioned surface ridge lying across the
Lower Peninsula.


.LONG TERM...(Sunday night through Thursday)
Issued at 347 PM EST Thu Dec 13 2018

High Impact Weather Potential: Minimal.

Colder air will likely arrive Sunday night/Monday across the Upper
Great Lakes...with deep layer northwesterly flow and 850mb
temperatures headed to -10C likely leading to lake induced snow
showers.  Right now doesn`t look like a major threat.  Moderating
temperatures for midweek as warm advection kicks in...with the
possibility of a short wave trough arriving in the Wednesday-
Thursday time frame.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1259 PM EST Thu Dec 13 2018

Once again, lots of MVFR cloud cover across the region. There are
some thin spots/clearing that may bring some temporary VFR weather
to the terminal sites. But overall, anticipate MVFR conditions
through the afternoon.

Tonight, surface trough across the Midwest today will cross
through the region later overnight into Friday. Increasing
southerly winds ahead of this system may actually help scour out
the lower cloud cover for a time, replaced by thickening mid and
high level cloud cover. Some light precip slides through the
region with this system, mainly in the form of very light snow,
although a little -FZDZ is also possible.


Issued at 347 PM EST Thu Dec 13 2018

A generally quieter stretch of weather anticipated heading into the
weekend, at least from a wind/wave perspective. Some stronger
westerly winds are possible on Friday/Friday night...and could
require a small craft advisory for some areas. Weakening winds into
the weekend.





NWS APX Office Area Forecast Discussion