Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 160424
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1124 PM EST Fri Dec 15 2017

.SYNOPSIS...
Weak low pressure to our north and south will provide clouds,
and maybe a few snow showers or flurries tonight into early
Saturday. High pressure builds in on Sunday, for a pleasant,
but chilly day. Two weak waves will move through early next
week bringing some rain and snow showers, as well as some warmer
air. It cools down again toward the end of the week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
1115 pm Update: Have adjusted POPs along the coastal and some
interior portions and based POPs off radar and then interpolated
some the slow progress to the east based off the trajs aloft.
The developing weak inverted offshore surface trof has made
enough west progress to shift a band of light snow to coastal
and interior portions. Some places along the midcoast may see
around a half inch or so with generally a dusting over most
other areas.

Also made some adjustments to increase POPs over the mountains
overnight as guidance suggests scattered showers to move across
area after midnight. Other than those changes input obs data and
minor tweaks to temps and winds.


1025 PM Update...Have increased PoPs a little bit for the next
few hours on the coastal plain based on latest observational
data. Short wave trough and low level convergence zone acting to
aid in the development of a little light snow on the coastal
plain (PWM, SFM, etc). This should shift northeastward and
mainly focus on the mid coast after midnight. However, a dusting
of snow will be possible outside of the mid coast through 1 am
or so. Otherwise, no further changes.

925 PM Update...Have made some slight changes in PoPs for the
overnight hours. Latest mesoscale model data and radar imagery
indicate that a weak convergence zone just offshore (weak NORLUN
trough) may bring a little light accum snow to areas northeast
of PWM...mainly the mid coast. Have increased PoPs a little bit
in those areas (especially the islands and necks) with an inch
or less accumulation. Otherwise, have chancy snow showers
further inland that shouldn`t last too long, re: 6sm -sn at DAW
and SFM this hour. This light snow or flurry activity may
continue to move northward over the next few hours with little
to no accums expected.

535 PM Update...Little change to the going forecast other than
lowering temperatures for the next several hours based on
observational trends. Otherwise, some snow showers are expected
in the far interior tonight in association with a short wave
trough. In addition, a more southern short wave trough could
allow some snow showers to graze southernmost and easternmost
zones tonight as well. The rest of the region should expect
cloudy conditions with perhaps a few flurries. Winds will be
light this evening.

Previously...

Expect increasing clouds tonight as a pair of shortwave troughs
pass through the area, one to the south and one to the north.
The one to the south is already producing light snow over
southern New York and moving into southern New England. Have
included mainly slight chance PoPs for this light snow as it
could bring a few flakes to southern New Hampshire and coastal
Maine overnight. Further to the north, another wave will bring
increasing clouds and perhaps a few mountain snow showers
overnight and into tomorrow morning. With cloud cover widespread
tonight, expect lows in the teens and single digits.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Slightly warmer air makes a brief appearance on Saturday ahead
of an approaching cold front. Temperatures may rise into the 30s
in southern and coastal areas. Upslope snows continue in the
mountains as the front arrives. Drier air moving in with high
pressure Saturday night should bring the upslope snows to an
end with temperatures falling back into the single digits and
teens again, but a few degrees colder than tonight.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
At 500 mb, flow becomes fast and zonal through a good part of
next week along much of the US/Canada border, with several
fast-moving and weak waves moving through New England. So for
the most part there will be some threats for precip /but no
significant storms/, with temps moderating mostly to near or a
little above normal.

Sunday will see surface ridge over the region shifting east.
The day should start sunny with high clouds thickening late.
Sunday will likely be the coldest day in the long range with
highs in the 20s.

Sunday night will see approach of the first of several waves,
and this one will be weak with little dynamic forcing, and lots
of low level dry air, so, it could produce a round of snow
showers starting late Sunday night, into Monday. Highs on Monday
look to be a few degrees warmer than Sunday but still in the
20s, except low 30s in SE NH. The one thing this system will do
is allow warmer air in from the SW behind it. So although
another wave quickly follows on its heels for Tuesday, temps
will rise into the 30s and low 40s on Tuesday with a threat of
snow or rain showers, mainly in the mountains. This system will
push a cold front through Tue night.

Wednesday looks cooler with upslope SHSN in the mtns, and highs
in the upper 20s N to mid to upper 30s in the south, and Thu
will likely be a little cooler with surface ridge overhead,
light winds and little mixing, with highs in the 20s to low 30s.

Friday may end up dry, but another system approaches from the
west which could affect late Friday into Saturday.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Short Term...VFR expected for the most part with light winds.
However, MVFR conditions in light snow are possible on the
coastal plain tonight, especially on the mid coast. Any snow
should be fairly light.

Long Term...Mainly VFR Sunday through Wed, although could see
tempo flight restrictions in SHSN Monday, and SHRASN on Tue.

&&

.MARINE...
Short Term...Although winds are light now, a cold front will
drop through and bring stronger winds by morning, with advisory
conditions expected on Saturday.

Long Term...Winds/seas relatively tranquil Sunday through
Tuesday, but may need SCA by Tue night into Wed.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 6 AM to 11 PM EST Saturday for
     ANZ150-152-154.

&&

$$
NEAR TERM...Marine
SHORT TERM...Marine
LONG TERM...Hanes



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