Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 221657
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1157 AM EST Sun Jan 22 2017

.UPDATE...
Issued at 1137 AM EST Sun Jan 22 2017

After coordination with surrounding offices, have decided to
extend the dense fog advisory for the entire CWA through noon on
Monday. Current observations show some improvement in visibility
across the area (especially for counties adjacent to Lake
Michigan) as temperatures warm up a bit, and visible satellite
does show a bit of thinning in some areas. The GFS is most in line
with the 22.12Z APX sounding, showing not as steep of a low level
inversion as the NAM/RAP/HRRR. The GFS might be a little
optimistic with mixing this afternoon, but it does appear to have
the best handle on the situation for today. At any rate, do expect
dense fog to persist for many areas through this afternoon and
visibilities to drop again tonight. Rather than cancel the
advisory for this afternoon and then reissue another one tonight,
have opted to simply extend the current advisory through Monday
morning.

&&

.NEAR TERM...(Today and tonight)
Issued at 311 AM EST Sun Jan 22 2017

...Simply more of the same...

High Impact Weather Potential: Periods of dense fog.

Pattern Synopsis/Forecast: Unseasonably mild and moist airmass
continues across the region, producing another night of rather
widespread dense fog. Deep layer south and southwest flow
responsible for this prolonged January thaw, with latest warm surge
tied to well defined shortwave trough pivoting north across western
upper Michigan. Primary warm front slowly moving north across our
area, south of which highs yesterday topped out well into the 50s.
Despite the proximity of this system, not a ton of rain overnight,
although passage of band of steep h8-h6 mid level lapse rates (see
00z local sounding) did manage to kick of a few rather robust
showers during the late evening and early morning hours. Real system
of interest is well to our southwest, with strong upper jet core and
attendant shortwave trough drumming up quite the early season severe
weather outbreak across the Gulf Coast states. This system will
continue to deepen as it heads across the southeastern states today
and tonight, all-the-while that upper Michigan wave continues its
northward journey into southwest Ontario by this evening. This
really puts our area in kinda a void region, with mid level heights
slowly inching upward through the short term. Band of "deeper"
moisture does attempt to pivot back west later tonight as low level
flow begins to respond to that intensifying southeastern storm. H8
thermal gradient really begins to ramp up across northern Lake
Michigan in the process, although per trends, best moisture is
displaced to the east and west of this gradient.

Primary forecast concerns: Mostly fog and temperature trends. Light
rain/drizzle chances will also need to be addressed.

Details: Weak warm front mixes north this morning, with band of
elevated showers out ahead of it likely clearing our area by
sunrise. Low level moisture remains abundant, and with continued
modification of the near surface environment via cold ground and
snow melt, feel current widespread dense fog will be slow to burn
off, with some fog likely persisting right through the day across
eastern upper Michigan and interior sections of northern lower
Michigan. Inherited dense fog advisory will remain through this
morning, although some areas may be trimmed sooner than that. Just
not seeing much precipitation potential for northern lower as mid
levels dry out and as the moist plume becomes increasingly focused
to the near surface environment. Not totally out of the realm of
possibility to sneak in a bit of sunshine at times this afternoon,
although feel this may be hard to come by given nearly non-existent
mixing potential. Moisture remains much deeper north of the big
bridge, but still short of ice nucleation level, so not expecting
much more than some patchy drizzle.

As mentioned, band of deeper low level moisture advances back west
later tonight, although with definite lack of any appreciable forcing
tied to it. Soundings show more of a drizzle look as this moisture
spreads west. Very light winds and near surface airmass modification
will continue to promote fog, some of which once again could become
quite dense.

As for temperatures, simply put, not a whole lot of change to what
has been occurring the last few days. Highs today very similar to
those experienced yesterday, with readings ranging from the upper
30s eastern upper to lower and middle 40s south of the bridge. Not
much nocturnal response tonight, with lows staying at least a few
degrees above freezing.

&&

.SHORT TERM...(Monday through Wednesday)
Issued at 311 AM EST Sun Jan 22 2017

...And more fog? well an end is in sight...

High Impact Weather Potential...Monday night into Tuesday, mixed
precipitation is expected. Tuesday night into Wednesday, mixed
precipitation is expected.

Pattern Synopsis/Forecast...Low pressure at the sfc and 500 mb moves
from the Ohio Valley, to the Mid-Atlantic states however, it will
have its affect on us with an inverted trough from the low up
through C upper, as another 500 mb shortwave trough moves into the
forecast area. This will produce light precipitation through the
day, and looks to be in the form of rain. Monday night, however,
colder air moves in at 850 mb and at the sfc which will bring a
mixed bag of precipitation. By Tuesday morning, the precipitation
may all be snow, but then change back to rain as the sfc
temperatures warm back up above freezing again. Only for the Mix to
move back into the forecast area, again at night with the cold air
moving from the North and east as the sfc high retreats and the warm
front remains south of US-10.

Primary Forecast Concerns...The low flow moisture trapped in the
boundary layer fog that we have been having, looks to remain into
Tuesday morning until the system moving out of the Plains and into
the Upper Great Lakes by Wednesday begins to get the air moving and
actually bring temperatures down again.

The mixed precipitation nights are the most concern as one or two
models are trying to crank out a lot of freezing drizzle/rain monday
night into Tuesday and Tuesday night into Wednesday. Looking at the
profiles, and thinking that freezing drizzle is more likely than
FZRA, went with the GFS idea, and so that rain briefly changes over
to FZRA or snow depending on where you are. This is certainly a risk
of FZRA in E Upper Monday night but think that with the profiles
more upright and saturated, think that the better bet is with the
rain changing to snow as the entire profile cools. That`s even more
so on Tuesday night into Wednesday.

.LONG TERM...(Wednesday night through Saturday)
Issued at 311 AM EST Sun Jan 22 2017

High Impact Weather Potential...lake effect snow Wednesday night
and through Saturday

Extended (Wednesday through Saturday)...Wednesday, the system moves
into the Mid-Mississippi Valley with the warm front over the
southern end of the state. Model blend continues to show a mix of
rain and snow on Wednesday as the sfc low passes to the south.
However, the sfc temperatures look to get into the mid to upper 30s
that day, so will remain with the mix, or all rain as the system
moves by. However Wednesday night, the cold air come back in behind
the low and changes the mix back to snow. This system keeps the 1000-
850 mb layer winds out of the NW, or NNW through the end of the
week, so will expect that there will various amounts of snow as the
850 mb temperatures cool and the wind directions vary with time.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 633 AM EST Sun Jan 22 2017

More of the same, with dense fog gradually lifting later this
morning, giving way to pockets of fog and br through the day.
IFR conditions during much of this period, although may see a few
hours later this morning and afternoon with low end MVFR cigs and
vis. Low level moisture further deepens with time tonight,
producing IFR conditions with more locally dense fog, low cigs,
and even some periods of drizzle. Light winds through this taf
period.


&&

.MARINE...
Issued at 311 AM EST Sun Jan 22 2017

Light winds today and tonight become a bit more gusty out
of the east on Monday, especially across northern Lake Huron. Light
winds return Monday night through Tuesday night. Fog, locally dense,
will continue at times through Monday.


&&

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

$$

UPDATE...MEK
NEAR TERM...MSB
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...MSB
MARINE...MSB


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