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-- Discussion containing changed information from previous version are highlighted. --
928
FXUS61 KCAR 131551
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
1051 AM EST Fri Dec 13 2019

.SYNOPSIS...
Low pressure tracks from the Mid-Atlantic States Saturday
morning, to the Lower Saint Lawrence River by Sunday morning.
The trailing cold front crosses the region Sunday, followed by
high pressure building in through Monday. Low pressure tracks
into southern New York and New England Monday night, then tracks
across the Gulf of Maine on Tuesday.
&&

.NEAR TERM /THROUGH TONIGHT/...
Update...
High pressure will exit across the Maritimes today, with a
developing warm front across the region. Isolated snow showers
are possible across mostly northern areas this morning. Expect a
slight chance/chance of light snow this afternoon. Have also
included patchy freezing drizzle later this afternoon across
portions of the west-central highlands. Little or no snow or ice
accumulation is expected through this afternoon. Otherwise,
expect cloudy/mostly cloudy skies this afternoon. Afternoon high
temperatures will range from the upper 20s to around 30 north,
to the mid to upper 30s interior Downeast with upper 30s to
around 40 along the Downeast coast. Have updated to adjust for
current conditions along with afternoon temperatures, clouds and
precipitation chances.

Previous Discussion...
Continued southerly flow tonight will result in increasing low
level moisture this evening. This could result in some patchy
freezing drizzle developing across the higher terrain late this
afternoon into early this evening. Deeper moisture begins to
arrive after midnight as an area of low pressure begins to track
northward from the mid atlantic region.

Across central and downeast areas, precipitation will be mainly
in the form of rain overnight. However, across the north, it
will be cold enough to support snow. The snow will then begin to
mix with and gradually change to rain toward daybreak. The
exception will be across northwest areas and the St. John Valley
where snow will persist, where an inch or two of snow is
possible by daybreak.

Lows tonight will occur early this evening, with temperatures
gradually rising overnight. Temperatures by daybreak Saturday
are expected to range from the lower 30s across the far north
and upper 30s to lower 40s across central and downeast areas.
&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Diffluent flow over the region Saturday as the axis of a deep
layered ridge lifts to the NE (how quickly it does so will determine
how fast heavier/steady rain moves in) and a developing closed low
slides into the eastern Great Lakes. AS a result expect moderate to
locally heavy rainfall to overspread the area from S to N Saturday
morning (starting off as some snow across the north). The rain
should continue into Saturday evening before tapering off from S to
N as the dry slot associated with the developing cutoff low moves in.

Expect rainfall amounts to total around 0.75"-1" across the north, 1-
1.25" across Bangor and Upper Penobscot Valley and 1.25-2" across
Downeast Maine. There is also the potential for 1-2" of snow to fall
across the North Woods before changing to all rain there by
afternoon. With generally less than an inch of snow expected
(outside of higher elevations) elsewhere across the North.

The heaviest rain Saturday should be in response to a 60-70 kt 950-
850 hPa low level jet passing just S of coastal SE Maine Saturday
morning. Fortunately, should be fairly inverted in the low levels, so
outside of higher elevations on Mt Desert Island, should not see
much in the way of wind mixing down from this low level jet. So
could see some 35 mph gusts near the coast (possibly some lower 40
mph peak gusts) and 20-25 mph gusts possible across the north. The
gusty winds and recent heavy rains should allow for some smaller
trees to possibly come down across Downeast Maine with the strongest
winds on Saturday.

Highs Saturday should be around 15-20 degrees above normal and lows
Saturday night around 10 degrees above normal. With persistent low
level warm advection - would not be surprising to see temperatures
slowly rise through the night (for now have rising in the evening
then leveling off overnight).

The cutoff low tracks into Newfoundland Sunday, then into the
Canadian Maritime Waters Sunday night. The result will be some
isolated to scattered rain and snow showers (North) and just rain
showers elsewhere Sunday with some mainly flurries possible across
the North Sunday evening. It will be breezy to windy (but for now
sub-advisory level winds) with falling temperatures due to strong
low level cold advection.

Highs on Sunday should be around 10-15 degrees above normal and
occur during the morning and off to the mid 20s to mid 30s (NW to SE
across the area) by late Sunday afternoon. Lows Sunday night should
be a few degrees above normal.
&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Deep layered ridging builds over the area Monday, with dry
conditions and diminishing winds. The ridging exits Monday night
allowing snow ahead of a northern stream shortwave trough moving
into the eastern Great Lakes to move into mainly SW portions of the
forecast area late Monday night.

This shortwave helps spawn a coastal low that moves across the Gulf
of Maine on Tuesday. This will bring some snow to most of Northern
and Eastern Maine, except for a mix of rain and snow right near the
immediate coast. This precipitation should taper off from W to E
Tuesday night as the low exits to the SE of Nova Scotia. There is
still quite a bit of uncertainty as to the exact track and strength
of this low, but based on a track to the S of Nova Scotia would
expect the highest snow totals across the Penobscot/Bangor Region
and interior Downeast Maine. Given the uncertainty, its too early to
forecast amounts at this time.

A closed upper low then tracks across S Quebec Wednesday then across
N Maine/New Brunswick Wednesday night. This should bring some
isolated-scattered snow showers to the region, with the highest
chance across the North.

Weak northern stream ridging is currently progged to cross the area
Thursday so it should be dry.

Temperatures should be below normal Monday-Thursday.
&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: Generally VFR conditions are expected this
morning, with VFR/MVFR conditions this afternoon. Could have
isolated snow showers across northern areas this morning. Will
then have a slight chance/chance of light snow developing this
afternoon. Have also included patchy freezing drizzle later
this afternoon across the west-central highlands to include
KGNR. Low level wind shear is a concern across northern areas
this morning into the afternoon, then developing across the
entire region tonight. Expect IFR to develop after midnight in
rain at the downeast terminals (KBGR/KBHB) and in snow and rain
at the northern terminals.

SHORT TERM: Saturday-Saturday night...IFR/LIFR. Snow or a wintry mix
transitioning to rain north, with rain Downeast. The rain ends from
SW to NE Saturday night. LLWS possible Bangor/Downeast terminals.

Sunday...IFR or lower with Isolated-scattered rain/snow showers
North and Isolated-Scattered rain showers elsewhere, improving
to MVFR-VFR late. SW-W winds G20-30KT possible.

Sunday night-Monday evening. VFR. W winds G25-35KT possible.

Late Monday night-Tuesday...MVFR or lower possible in snow, with a
rain/snow mix possible near the immediate coast. NE-N winds G15-25KT
possible.
&&

.MARINE...
NEAR TERM: Winds/seas are expected to be below small craft
advisory levels this afternoon, though a few gusts to 25 knots
are possible. Winds/seas will then increase to small craft
advisory levels tonight. A Small Craft Advisory has been issued
beginning late tonight.

SHORT TERM: SCA conditions on all waters Saturday-Saturday night,
with some isolated gusts to 35-40kt possible on the coastal ocean
waters mainly Saturday morning with the passage of a low level jet.

Gales then probable all waters Sunday-Sunday night with strong low
level cold advection.

Winds diminish to SCA levels Monday then to sub-small craft levels
Tuesday (depending on exact evolution of a coastal low progged
to track across the Gulf of Maine Tuesday). SCA level seas
could linger on Tuesday on the coastal ocean waters.
&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory from 5 AM Saturday to 6 AM EST Sunday for
     ANZ050>052.

&&

$$

Near Term...Norcross/Duda
Short Term...Maloit
Long Term...Maloit
Aviation...Norcross/Duda/Maloit
Marine...Norcross/Duda/Maloit