Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 211138
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
638 AM EST Sat Jan 21 2017

.UPDATE...
Issued at 636 AM EST Sat Jan 21 2017

Dense fog is not widespread. Was thinking that it could redevelop
toward daybreak with the arrival of an increase in low level
moisture and drizzle, but that has not occurred. There is some
dense fog in spots, but again, not widespread for the Dense Fog
Advisory.

&&

.NEAR TERM...(Today)
Issued at 333 AM EST Sat Jan 21 2017

High impact weather potential: Dense fog, again.

Pattern synopsis and forecast:

Early this morning, one shortwave trough has exited north of the
area while another was working up through the mid Mississippi
valley, and was associated with a sfc low in Iowa. A warm front
extended from this low through nrn IL/IN, with the next batch of
deeper low level moisture north of it and working through srn lower
and the srn half of Lake Michigan. Embedded within this deeper
moisture were some spotty light rains and drizzle. Across nrn
Michigan, we are still stuck in widespread stratus and fog, but
there were some areas with the low stratus lifted out and improved
visibilities. Damp conditions with temperatures still in the lower
half of the 30s makes it feel quite chilly out there.

Not much will change through tonight in the weather department,
despite the aforementioned shortwave trough and associated sfc low
and warm front lifting up into nrn Michigan. There is just not a
deep moisture tap, but fcst soundings do show a couple of periods of
increased low level moisture for spotty light rain and drizzle. The
first comes this morning for mainly nrn lower, with the band of
deeper moisture north of the warm front. These spotty light rain and
drizzle will then exit eastern upper by early afternoon. By this
time, the warm front will by draped across nrn lower with weak
convergence in light near sfc winds. This cyclonic nature of the
winds with the front will lead to continued chance for seeing drizzle
through tonight. There is a stronger signal of shallow WAA with the
front, and do believe that despite low clouds and fog, temperatures
will be able to rise into the upper 30s north, and the lower 40s
south. It will still feel rather chilly however due to the dampness
outside.

We currently have a dense fog advisory issued and will continue that
into this morning, despite area observations not showing as much
dense fog as yesterday early morning. Conditions with the deeper low
level moisture do show quarter mile or less visibilities, am just
unsure as to how widespread it will be. Fog will be around through
tonight yet again, but am somewhat unsure as to how dense it will
be. Near sfc winds do get a bump more out of the SW behind an ill-
defined occluded/cold front. This cooler near sfc air could help set
the stage for widespread dense fog as the low level moisture will
remain plentiful. Additional advisories may be needed again. Lows
tonight in the mid and upper 30s.

&&

.SHORT TERM...(Tonight through Monday)
Issued at 333 AM EST Sat Jan 21 2017

...Mild for a time before mixing again...

High Impact Weather Potential...Dense fog is possible Sunday
morning, otherwise, Monday night, mixed precipitation is expected.

Pattern Synopsis/Forecast...We continue the current pattern of weak
sfc flow with a strong inversion trapping the moisture from the
melting snow. However, as each afternoon the last couple of days,
the afternoon will also see the fog lift, but also since the
gradient begins to tighten up in the late afternoon as a storm
system in the Ohio Valley deepens and brings more moisture, but now
with the inverse trough from the low, rain through the day on
Monday. Then we actually get some cold advection as the moves into
the Mid-Atlantic region. Our rain looks to mix with snow overnight,
and in E Upper, maybe some freezing rain before changing to all snow
by Tuesday morning.

Primary Forecast Concerns...Main issue is that the models are
showing marginal profiles for freezing rain in E Upper. Will leave
it in for now, but think that the blend of models is bringing in too
much warm air aloft, based on the NAM sounding which is the only
model to show a classic freezing rain sounding.

.LONG TERM...(Monday night through Friday)
Issued at 333 AM EST Sat Jan 21 2017

High Impact Weather Potential...Mixed precipitation Tuesday, and
then Wednesday more mixed precipitation with some moderate snow as a
storm moves through the state.

Extended (Tuesday through Friday)...Snow Tuesday morning will change
back to rain before ending as high pressure briefly moves into the
region. Then the Wednesday system moves into the Mid-Mississippi
Valley with the warm front over the southern end of the state. This
brings rain back into the forecast area Tuesday evening before
changing over to snow overnight. Model blend shows a mix of rain and
snow on Wednesday as the sfc low passes to the south with all of the
warm air. Thinking that the colder ECMWF is better, but will keep
the mix for now. However, Wednesday night, the cold air come back in
behind the low and changes any mixes back to snow. This system is
enough to effect a change in the pattern to put us back into all
snow showers, and maybe some lake effect for Thursday and Friday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 636 AM EST Sat Jan 21 2017

Low level moisture remains rich underneath an inversion. Same
story as the last few days. IFR conditions expected to be the rule
once again with areas of fog and stratus combined with periods of
drizzle. Cooler near sfc air leaks in overnight and will possibly
result in more widespread dense fog. Light ESE winds.

&&

.MARINE...
Issued at 333 AM EST Sat Jan 21 2017

The pressure gradient remains pretty weak through Sunday night with
fairly light ESE/variable winds. Winds pick up out of the east
Monday as we get into the nrn end of the tighter gradient of
stronger low pressure working into the mid atlantic states. Periods
of light rain and drizzle through Monday with possibly a little
light snow mixed in Monday night.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY until noon EST today for MIZ008-015>036-041-
     042.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...SMD
NEAR TERM...SMD
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...SMD
MARINE...SMD


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