Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 291855
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
155 PM EST Tue Nov 29 2016

.UPDATE...
Issued at 1036 AM EST Tue Nov 29 2016

Deep, stacked low pressure system spans the upper midwest/northern
plains region this morning with an occluded front arcing east/
southeastward to just north of the Soo, through SE Ontario into
New York. Widespread rainfall with the front has completely pushed
north and east of Michigan at this juncture, replaced with a
pronounced dry slot rounding the upper low (along the northern
side of a strong upper jet) from the central plains and midwest
up through lower Michigan. So, mainly clear skies prevailing
across lower Michigan at this point, with a bit more cloud cover
still across upper Michigan.

Rest of today, stacked upper low will just inch eastward keeping
region of strong subsidence and dry slot stretched through much of
the Great Lakes. Thus pretty much status quo at this point, with
a good deal of sunshine prevailing across lower Michigan and a bit
more cloud cover in the U.P. Nice core of 30 to 40 knot winds in
the mixed layer will slide up through the CWA through the day
making for a rather breezy day with 25 to 35 mph gusts common, a
bit stronger along the Michigan coast. However, don`t think we
will see advisory level winds (gusts to 45 mph or more).

Otherwise, another very mild day with temperatures running nearly
20 degrees above normal.

&&

.NEAR TERM...(Today and tonight)
Issued at 237 AM EST Tue Nov 29 2016

...Warmer yet as rain ends...

High Impact Weather Potential: Nothing too significant. Still
expecting some gusty southwest winds today, particularly across the
big waters.

Pattern Synopsis/Forecast: Textbook rain-maker across the Lakes this
overnight, with strong upper level jet dynamics above falling mid
level heights (via approaching short wave). Low level wind fields
have responded accordingly, with 70+ knot h8 jet core and its
associated mass convergence aimed right at northern Michigan. All
the above are working over one unseasonably moist Gulf of Mexico
originated airmass (precipitable water values in excess of three
quarters of an inch), resulting in a widespread soaking rain for the
region. This corridor of deep lift/moisture is a fast moving one
however, with aggressive drying already punching into our
southwest counties just behind passing occluded front. Whole
system is part of much broader troughing, the center of which is
back across the Northern Plains. While this troughing will be slow
to yield in the coming days, that approaching dry slot will be
anything but, quicky moving northeast through our area this
morning.

Primary Forecast Concerns: Timing of rain ending today. Additional
light shower threat later tonight. Wind and temperature trends
through the forecast.

Details: Simple observations supports continued rapid northeast
movement of upstream dry slot/occluded front this morning, ending
the rain threat from southwest to northeast in the process. Drying
is soo aggressive, that unlike typical November systems, cloud
cover even looks to scour out shortly after the rain ends, leaving
partly to mostly sunny skies south of the big bridge this
afternoon. Cloud cover will remain a touch more stubborn across
eastern upper, but even here would expect some afternoon sun.
Combination of a deepening mixed layer and h9 temperatures well
into the single digits easily supports highs well into the 50s for
northern lower, and just a few degrees cooler from the Straits
north. Its definitely gonna stay windy, with winds veering
southwest after frontal passage. Just how windy is still subject
to some debate. Secondary low level jet pushing 40+ knots quickly
develops this morning. Bufkit momentum transfer suggests the full
extent of this wind maxima will not likely mix to the surface.
Still, would expect to easily see widespread wind gusts in excess
of 30 mph, with isolated 40 mph gusts likely right along the shore
of Lake Michigan. If more vigorous mixing is realized, may even
tip the scales to low end wind advisory conditions along the
shores of northwest lower Michigan. Something definitely to
continue to monitor.

Winds quickly subside tonight as low level jet is lost and pressure
gradient relaxes. Clouds will be on the increase overnight as next
wave/elongated vort max pivot north into the area. Could even see
the return of some patchy light rain/drizzle, with the development
of moisture rich low levels also supporting late night fog
development. What does fall tonight will definitely stay liquid,
with temperatures only falling into the upper 30s and lower 40s.

&&

.SHORT TERM...(Wednesday through Thursday night)
Issued at 237 AM EST Tue Nov 29 2016

...The beginning of day rain night snow cycle...

High Impact Weather Potential...Minimal

Pattern Synopsis/Forecast...The Northern Plains low that is over the
Dakotas at the moment, will begin to rotate into the Upper Great
Lakes during the day on Wednesday, pushing the cold front into the
region. SPC has thunder associated with the front, but Looking at
what is going on with the low, and that the dynamics for this system
is over SE Lower and continues sliding east, think that any thunder
is so low of a chance that it`s not worth putting into the forecast.
Models show a decent dry slow that moves through and brings
precipitation to a stop before restarting when the upper level low
moves over the forecast area and brings a rain/snow mix to the
interiors of the region. high temperatures are expected to be around
40f by Thursday afternoon, so will expect that the snow will change
over to rain during the day, and then change back to snow overnight

Primary Forecast Concerns...precipitation type will be the key to
the snow amounts through the time period. If temperatures take
longer to recover, or the models are too warm, and that would be
more likely in a cold advection situation like this, then light snow
accumulations will appear, especially in the interior of N Lower and
E Upper. Models show a muddled temperature gradient after the low
moves through, so as of now, the cold advection is weak. This would
produce temperatures that numbers are advertising at the moment.
Part of the muddled 850 mb is that the low becomes big enough to
pull Atlantic air over the top of the low back into the region
across the N Plains.

.LONG TERM...(Friday through Monday)
Issued at 237 AM EST Tue Nov 29 2016

Models have evolved the pattern so that the lake aggregate trough
is more defined and thus, we end up in a NNW or NW flow Lake
Effect regime. 850 mb temperatures are around -7c with the water
temperatures around 10c depending on the lake. So have bumped the
pops up for Lake Effect from Thursday afternoon through Sunday
morning. Sunday is where the models still diverge substantially
with the GFS and GEM still showing the relatively fast and flat
500 mb flow, while the ECMWF and UKMet are bringing the 500 mb cut
off low out of the Desert SW and bombing a sfc low from it in the
Gulf Coast States, now bringing it up to KTOL by Monday/12z. This
would bring a decent snow to areas in NE Lower and SE Lower,
possibly even farther north and west Overnight Sunday. Am in
agreement with the WPC idea of going with the GFS, as the ECMWF
has a tendency to eject energy from the Desert SW too fast. So
will probably see varying amounts of LES per the GFS.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 155 PM EST Tue Nov 29 2016

Solid VFR conditions will persist at the terminal sites this
afternoon into tonight, although gusty winds will continue through
the afternoon hours with gusts pushing 30 knots. Gustiness will
diminish heading into the evening and winds will further diminish
to under sustained 10 knots later this evening and overnight.

Tonight: Weak-ish short wave over the mid Mississippi river
valley will slide up through lower Michigan...ahead of a strong
cold front now pressing into the midwest. Along with steeper
lapse rates aloft/marginal instability, may kick off some showers
that will skirt parts of NE lower Michigan mainly during the
overnight hours. But guidance also suggests a batch of low (MVFR)
cloud cover and some fog developing upstream ahead of the front and
spreading up into northern lower Michigan overnight, then persisting
through Wednesday as the front eventually slides through the region.
Will have to see how that unfolds as we go through the evening,
but for now have flight conditions lowering to MVFR at all
terminal sites overnight through Wednesday morning.

&&

.MARINE...
Issued at 237 AM EST Tue Nov 29 2016

Winds will quickly veer southwest this morning behind a passing
occluded front. Strongest winds, gale force at times, will focus
across northern Lake Michigan in the process, enhanced some
through coastal convergence and Manitou Passage channeling. While
remaining gusty, gale conditions are likely to subside elsewhere,
although may last a bit longer down near Saginaw bay. Winds will
gradually weaken and become more variable tonight into Wednesday
as a weaker pressure gradient arrives. There will be an uptick in
westerly winds Wednesday night into Thursday as cold advection
sets in, with potential advisory level gusts.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 4 PM EST this afternoon for
     LHZ345>349.
LM...SMALL CRAFT ADVISORY until 4 PM EST this afternoon for LMZ323-
     341.
     GALE WARNING until 4 PM EST this afternoon for LMZ342-344>346.
LS...SMALL CRAFT ADVISORY until 4 PM EST this afternoon for LSZ321-
     322.
&&

$$

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



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