257
FXUS63 KAPX 212300
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
600 PM EST Mon Jan 21 2019

.NEAR TERM...(Through Tonight)
Issued at 356 PM EST Mon Jan 21 2019

...A bit of a moderating trend...

High impact weather potential: None.

Pattern synopsis/forecast: Center of Arctic high pressure,
responsible for the dangerously cold conditions of late, now pushing
off to our southeast, with parent mid-level ridge axis just now
building into the region. After early morning temperatures that
where well below negative 20F in our traditional colder locations,
gradually development of south return flow and plenty of sunshine
has "boosted" readings into the single digits and lower teens early
this afternoon. Of course, those same light winds make it feel just
a bit colder, with wind chill values generally in the single
digits.

Both the surface and upper level flow regime remain quite
progressive tonight, with surface high pressure pushing off to the
East Coast while mid level ridge axis builds into and through the
northern Great Lakes. This results in further maturing of warm air
advection, keeping overnight lows several degrees "warmer" than
previous nights, and even bringing the possibility of a little light
snow toward Tuesday morning.

Primary forecast concerns/challenges: Cloud/temperature trends and
addressing that late night light snow potential.

Details: South winds will be on the increase tonight as pressure
gradient increases between departing surface high and developing
Southern Plains low pressure. Increasing warm air advection through
the column will result in slow top-down saturation, bringing slowly
increasing and lowering clouds with it. Saturation looks to become
deep enough to generate a bit of light snow late tonight, although
as previous forecaster mentioned, gotta wonder if guidance is
simply too aggressive with this idea given such a dry overhead
airmass. Any snow that does fall will remain light, with amounts
under an inch.

Combination of those winds and increasing clouds will really prevent
temperatures from falling too much tonight, and may actually see
temperatures start to rise very late tonight. Expect lows generally
in the single digits, although areas in the Au Sable River valley
will likely dip several degrees below zero quickly this evening
before recovering some later tonight. Wind chills will remain quite
cold, in the single digits to teens below zero. Not headline worthy,
but make sure you take proper precautions if venturing outside
overnight.

&&

.SHORT TERM...(Tuesday through Thursday)
Issued at 356 PM EST Mon Jan 21 2019

...Not as cold with widespread snow...

High Impact Weather Potential...Fairly high.

Primary Forecast Concerns...Snow accumulations late Tuesday into
early Wednesday.

Low pressure emerges out of the central Plains tonight, heads
northeast and tracks across northern lower Michigan Tuesday night
into Wednesday morning. There will be strong warm
advection/isentropic upglide in advance of this system. Models have
come into decent agreement with snow amounts. Forecast accumulations
will generally range between 6 and 8 inches across eastern upper
(enhancement due to a possible frontogenetical band) and 4 to 6
inches across northern lower (highest near the Staits and lowest
across southeast counties where a little rain could mix in).
Headlines will likely be advisory level but will defer this decision
to the midnight shift as the bulk of the snow will not fall until
the third period of the forecast (Tuesday night into easy
Wednesday). It then looks like some north northwest flow lake effect
snow showers during the day Wednesday with a break in the action
expected Wednesday night.

.LONG TERM...(Thursday night through Monday)
Issued at 356 PM EST Mon Jan 21 2019

High Impact Weather Potential: Active weather continues with several
chances for accumulating snow through the weekend, along with
another round of potentially very cold temperatures.

An Alberta Clipper and associated arctic cold front move through
late Thursday into Thursday evening with northwest flow lake effect
to follow. The Clipper/front should bring a round of snow showers to
the region. The lake effect behind it looks rather robust with
decent moisture and gusty winds. This in combination with the very
cold air (and low wind chills), visibilities will likely be lowered
at times (small dendrites). This pattern is expected to continue
into the weekend with periodic short waves moving through the flow
enhancing activity. The one limitation may end up being the
increasing ice cover on the big lakes. Temperatures will be upwards
of 20 degrees below average. Highs on Friday will struggle to reach
above zero once again.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 600 PM EST Mon Jan 21 2019

Strong arctic high pressure center will continue to slide east
away from Michigan tonight...as low pressure continues to develop
to the lee of the Rockies in the Central Plains. This system will
gradually lift NE toward the Great Lakes region Tuesday and
Tuesday. Widespread snow will develop ahead of the system and will
impact all of Michigan beginning on Tuesday and continuing Tuesday
night and into Wednesday. Conditions will deteriorate to MVFR/IFR
as this widespread snow develops. LLWS will develop as southerly
flow strengthens ahead of this system tonight into early Tuesday.

&&

.MARINE...
Issued at 356 PM EST Mon Jan 21 2019

After some lighter winds today, widespread southerly
advisory and possible gale producing winds return tonight into
Tuesday, as the pressure gradient tightens between departing high
pressure and developing low pressure in the Central Plains. The
gradient will loosen up some and winds will decrease later Tuesday
and Tuesday night as the low pressure lifts up into nrn Michigan.
Widespread snow is expected as this system passes.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 5 PM EST Tuesday for LHZ346-347.
     SMALL CRAFT ADVISORY until 6 AM EST Wednesday for LHZ348-349.
LM...SMALL CRAFT ADVISORY until 5 PM EST Tuesday for LMZ323-341-342-
     344>346.
&&

$$

NEAR TERM...MB
SHORT TERM...AS
LONG TERM...AS
AVIATION...MR
MARINE...MB