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National Weather Service Gaylord Michigan
635 PM EST sun Dec 21 2014

Near term...(this evening through tonight)
issued at 341 PM EST sun Dec 21 2014

Happy winter solstice everyone...the good news is that days will
be getting longer from here on out (not that anyone will be able
to tell for a while). Weather wise...short wave evident on water
vapor imagery across far northern Minnesota and southwest Ontario
will move northeast across Lake Ontario tonight. Not much
moisture/lift down this way but this feature may scrap eastern
upper...mainly Chippewa County and western portions of Mackinac
County with a little light snow (only like half an inch at best).
Meanwhile...low clouds remain entrenched across the region which
may attempt to lift out due to warm air advection leaving an
extensive middle level cloud deck. My bet would be for the low cloud
deck to remain but either way...cloudy skies should continue
across the entire area. Temperatures are not expected to drop much
tonight with lows only ranging from the mild middle 20s to middle
30s.

&&

Short term...(monday through wednesday)
issued at 341 PM EST sun Dec 21 2014

..wet to start the Holiday week then turning colder...

Weather impacts: winter storm potential for Christmas evening/day has
diminished in latest model trends. Still cautiously watching this
system.

Synoptic overview: strong Pacific jet energy continues to pour into
the Pacific northwest/British Columbia region this morning...squeezed between
strong ridging just off the Southern California/Baja California region and a fairly
deep trough axis along 165w. Middle level flow downstream across the
central Continental U.S. Already starting to buckle today under the influence
of incoming short wave energy in the northern rockies (and a couple small
scale waves moving through the plains). Across the Great
Lakes...subtle middle level ridging is currently moving across the
region with a ridge of surface high pressure just off to the east into
New England. But abundant stratus is draped from the Midwest into
northern Michigan bringing a rather drab winter solstice to the North
Woods.

Forecast overview: Pacific short wave energy still slated to dig out
a deep closed surface and upper low across the plains over the next 24
hours. Initial surface low that deepens in the plains slowly weakens and
migrates into the upper Midwest/western Great Lakes by Wednesday and
still looking to bring a round of (mainly) rain to the County Warning Area Monday
night into Wednesday...although there will be some icing concerns
initially Monday night (see below). But unfortunately...there remain
more questions than answers specifically around midweek for a high
impact weather event. Guidance trends had been backing off on the
strength of this system with the initial surface low/upper wave
weakening and moving through the Great Lakes midweek. But...todays
12z guidance (gfs and euro) are more aggressive in digging short
wave energy deep into the southern states and Gulf Coast then
lifting this wave (and a quickly deepening surface low) up through the
Ohio Valley and central Great Lakes. Of course...model solutions
vary with the Euro taking a bit more eastward track through Lake
Erie...GFS runs this system up through lower Michigan. Yet one more
potential scenarios for the Christmas evening/Christmas day time frame.

Monday...probably the "quietest day" of the upcoming Holiday week.
May still be some light warm advection snowfall exiting through
eastern Upper Michigan into Ontario early Monday morning. But
otherwise...dry weather will prevail under mostly cloudy skies and
increasing southerly winds...which should finally push temperatures to
above freezing for most areas.

Monday night through Tuesday...short wave trough closes off and
deepens through the plains/Midwest with attending surface low sliding
into the western Great Lakes. Deep warm air/moisture transport
develops ahead of this system Monday night. Aided by exit region
upper jet forcing that noses up into the lower Great Lakes by
Tuesday...should result in a nice push of precipitation. Forecast
soundings Monday night suggest rain for northern lower Michigan and a
rain/snow transition across eastern Upper Michigan where up to an
inch of snow is possible. But...with surface temperatures dipping back down to
at or below freezing Monday evening...am increasingly concerned we
end up with several hours of light freezing rain across the higher
terrain of northern lower Michigan and up to a tenth of an inch of ice
accumulation. Not enough for a warning...but some type of advisory
headline may eventually be needed. Surface temperatures will eventually rebound
to above freezing by Tuesday and remain there through Wednesday with
periods of light rain/fog through that period. Enough cold air could
bleed back into the region Wednesday to see some sort of changeover
during the day. But as mentioned above...a lot of uncertainty still
surrounds the midweek time frame.

&&

Long term...(wednesday night through sunday)
issued at 341 PM EST sun Dec 21 2014

Models are still in disagreement with exactly what this primary
system will do...but one thing is becoming clear...there seems to be
no Great Lakes bomb that was previously thought. Also beginning to
be more confident that the rain will begin to change over to snow
during the overnight hours of Christmas evening from west to east. Once
temperatures do fall below zero and the ground cools enough for the
snow to actually stick into Christmas afternoon the wrap around
moisture is almost non existent as it rapidly exits east with the
departing system. All-in-all there is a potential for at least some
picturesque dendritic flakes falling Christmas day.

The secondary storm system later in the period towards the weekend
still is very uncertain to where it will track...or if it will even
come to realization. With too many possibilities to begin to even
mention...from rain to a big snow maker. Will continue to hold off
until greater confidence is achieved. Temperatures will drop
throughout Christmas day...starting in the low to middle 30s in the
morning and dropping into the low to middle 20s by the evening hours.
The cooling trend will continue with high temperatures Friday near
freezing...Saturday in the middle 20s...and then Sunday only in the
upper teens to low 20s. Low temperatures both Friday and Saturday
mornings will be in the upper teens to low 20s...with Sunday morning
possibly dropping into the single digits to low teens.

&&

Aviation...(for the 00z tafs through 00z Monday evening)
issued at 634 PM EST sun Dec 21 2014

Mainly VFR...with some MVFR ceilings this evening...and apn becoming
MVFR on Monday. Low level wind shear late tonight tvc/mbl.

Southerly low-level flow is in place...behind high pressure moving
down the St Lawrence Valley. The low levels remains somewhat
moist...and there are some tatters of MVFR ceilings in parts of
northern Michigan. That will continue to be a risk this evening. On
Monday...as southeast winds off of Lake Huron get a little stronger...a
stratus deck will likely intrude on apn.

Surface winds will be from the S to southeast...mainly 10kt or less. Low level wind shear
late tonight mbl/tvc...as due south winds just off the deck
increase to around 30kt.

&&

Apx watches/warnings/advisories...
Michigan...none.
LH...none.
Lm...none.
Ls...none.
&&

$$

Near term...Sullivan
short term...Adam
long term...tjl
aviation...jaz

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