Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 102315
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
615 PM EST Sun Dec 10 2017

.SYNOPSIS...
Weak low pressure will approach from the west tonight and then
move east Monday. High pressure will build across the region
Monday night. Strong low pressure will lift across the region
later Tuesday through early Wednesday.

&&

.NEAR TERM /THROUGH MONDAY/...
600 PM Update: A sct to bkn ln of heavier sn shwrs and
potential sn sqls are rapidly movg E across NE ME erly this eve
ahead of an arctic cold front which will likely cross into Nrn
and Cntrl ptns of the FA this eve into ovrngt. PoPs were beefed
up somewhat erly this eve, and then merged to the fcst late
tngt. Given the speed of these sn shwrs/sqls, snfl potential
should be lmtd to a half to full inch.

Orgnl Disc: The low pressure system that brought the first
measurable snowfall to much of the region last night has moved
well east of the Canadian Maritimes. A westerly flow of drier
air has moved into the area in the wake of the low. Our
attention now turns to an arctic frontal boundary just to the
northwest of the state. Behind the boundary, temperatures this
afternoon were only in the single digits above zero to lower
teens across much of Quebec province. This boundary will begin
to cross northern portions of the region tonight. An upper
disturbance will also cross northern areas through early this
evening with a chance of snow showers, and even a brief snow
squall mainly across far northern areas and the St. John Valley.
We should then see a brief break in any snow shower activity
through the first half of the night. However, a weak area of low
pressure across southern Quebec is expected to track east along
the boundary and across far northern Maine toward daybreak on
Monday. This will result in another chance for snow showers
after midnight, mainly across northern and western areas. In
addition, another weak area of low pressure is expected to
develop along the down east coast as short wave energy rotates
east around the upper trof. This low is expected to move quickly
east into the Canadian Maritimes early Monday. Near term models
are keeping the bulk of the moisture with this feature just
offshore and to our east. However, it looks like the immediate
down east coast could see a brief period of light snow with this
system after midnight into early Monday morning. Precipitation
amounts look to be light, less than a tenth of an inch, so any
snow accumulation looks to be an inch or less. Brought the
western edge of likely pops(60%) just into the immediate down
east coast late tonight into early Monday morning. Otherwise,
any morning snow showers across the north and light snow along
the down east coast will give way to at least partly sunny
conditions, with perhaps a few lingering afternoon flurries by
afternoon. Lows tonight will range from the single digits above
zero across the St. John Valley to the upper teens to around 20
down east. Highs on Monday will range from the mid teens to
around 20 north and upper 20s to lower 30s Downeast.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
High pressure will exit to the east Monday night while
intensifying low pressure tracks across the eastern Great Lakes.
Cloud cover will increase across the region Monday night. The
low will track toward southern Maine Tuesday. Snow will expand
northeast across the region Tuesday. Onshore winds will draw
warmer air toward the Downeast coast during the afternoon,
which could allow the snow to mix with rain or transition to
rain during the afternoon into the evening. The low will lift
northeast across Maine Tuesday night, though the exact track is
still uncertain. Snow will persist across northern areas Tuesday
night. However, dependent on the track, warmer air being drawn
north could allow the snow to transition to a wintry mix
particularly across eastern areas. Snow, or a wintry mix, early
Tuesday night Downeast will taper to snow showers overnight.
Have issued a Winter Storm Watch for most of the forecast area,
with the exception of the Downeast coast, Tuesday morning into
Wednesday morning. The heaviest snow totals are expected across
northern Aroostook county, where amounts in excess of 8 inches
are possible. Lesser snow accumulations are expected southward
across the remainder of the forecast area, dependent on the
eventual track of the low. The least snow is expected along the
Downeast coast where the snow should transition to rain or mix
with rain. The surface low lifts toward the Gulf of Saint
Lawrence Wednesday while the upper low crosses the region.
Deformation zone snow or snow showers will persist across the
north and mountains Wednesday with the upper low and wrap around
moisture from the surface low. Mostly cloudy skies along with a
chance of snow showers are expected Downeast Wednesday.
Temperatures will be at below normal levels Tuesday, with
slightly below normal level temperatures Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Could still have a chance of snow showers across the north and
mountains Wednesday night, with decreasing clouds Downeast. High
pressure will build across the region Thursday. Low pressure
should intensify east of the region Friday. Dependent on the
track of the low, the western edge of the precipitation shield
could bring a chance of snow to the region. High pressure is
expected Saturday. Low pressure should approach from the west
Sunday with a chance of snow. Temperatures will be at below
normal levels Thursday through Sunday.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
NEAR TERM: VFR conditions to start the evening but we could see
brief MVFR/IFR conditions developing this evening in any sct
snow showers activity associated with an approaching frontal
boundary. Mainly VFR on Monday but again could see briefly lower
conditions in scatterd snow showers, mainly north.

SHORT TERM: VFR conditions are expected Monday night. Conditions
will lower to IFR/LIFR levels across the region Tuesday morning
through the afternoon. IFR/LIFR conditions are then expected
Tuesday night into Wednesday morning. Occasional MVFR
conditions will then persist Wednesday afternoon. Occasional
MVFR conditions will persist across the north and mountains
Wednesday night into Thursday. Occasional MVFR conditions are
possible Downeast early Wednesday night, with VFR conditions
overnight into Thursday. Conditions Friday will be dependent on
the eventual track of low pressure and whether snow is wrapped
back across the forecast area.

&&

.MARINE...
NEAR TERM: A small craft advisory is in effect through early
Monday morning. Small craft advisory may be needed into Monday.

SHORT TERM: Small craft advisory conditions are expected Monday
night into Wednesday. Visibilities will be reduced in rain and
snow Tuesday morning into Wednesday morning.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Watch from Tuesday morning through Wednesday
     morning for MEZ001>006-010-011-015>017-031-032.
MARINE...Small Craft Advisory until 7 AM EST Monday for ANZ050>052.

&&

$$

Near Term...VJN
Short Term...Norcross
Long Term...Norcross
Aviation...VJN/Norcross
Marine...VJN/Norcross


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