Area Forecast Discussion
Issued by NWS Portland, ME

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051
FXUS61 KGYX 052009
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
309 PM EST Thu Dec 5 2019

.SYNOPSIS...
A cold front will sweep across the forecast area this evening.
Another low pressure system will pass near or south of the
region on Friday with an additional chance for light snow in
southern and western areas. This system will usher in
significantly colder weather for Saturday. Warmer temperatures
perhaps with some rain is expected early next week before a
cold front brings in another dose of Arctic cold.

&&

.NEAR TERM /TONIGHT/...
Cold front beginning to move across the forecast area as of
1930z with gusty winds and a few snow showers or isolated
squalls. This front will sweep across the rest of the forecast
area by early evening with brisk conditions and the possibility
of a squall or two. Colder temperatures are expected tonight in
the wake of the front with lows mainly in the teens and wind
chill values lower than that as winds will probably not decouple
all night in most areas. Upslope snow showers will continue in
the northern Whites and adjacent western ME mountains through a
good portion of the night.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A quick-moving short wave trough will approach the forecast area
from the west Friday morning. Much of the members of the 12z
model suite are in better agreement today on the degree of
amplification and track of the short wave trough, SFC low track,
and subsequent shield of light snow. The ECMWF continues to be
the most consistent from run to run with the more northerly
track of these features so leaned that direction in the
forecast blend for PoPs and QPF for Friday. Even though the NAM
and GFS models are slightly further south, the track of their low
and mid level frontogenesis and -EPV (and associated potential
symmetric instability) fields favor the ECMWF forcing and QPF
fields.

Light snow should arrive across western zones late in the
morning, quickly spreading across central/southern NH and
southern ME through the afternoon hours. Expecting a coating to
an inch in most areas roughly south of a KLEB-KPWM line with a
few spots possibly picking up around 2". North of that line,
forcing for ascent will be weaker and low level RH values will
be quite low. Therefore, less than an inch expected north of the
aforementioned line, with little to no accums expected in much
of central ME northward into the mountains.

Overall this is a light snow event that will probably only last
6 hours in the afternoon to early evening and certainly pales
in comparison to the storm we experienced earlier in the week.
However, a coating to 2" of snow on the roads during the
afternoon and evening commute tends to cause quite a few traffic
issues. We`ll highlight in the HWO and may need a special
weather statement come late tonight or Friday morning.

Otherwise, the system quickly moves away Friday evening with at
least partial clearing and cold temperatures in it`s wake.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Core of the cold behind the front will be in place on Saturday
as high pressure builds into the area. Expect highs in the 20s
area wide despite a good amount of sunshine downwind of the
mountains. Saturday night the high moves across the area. Expect
even the lingering clouds in the mountains to disperse as the
upslope flow ends and winds go calm across the region. This
will set the stage for a very cold night with most of the area
expected to see single digit readings. The coldest valleys could
dip to zero. High pressure moves east Sunday opening our area up
to a southwest flow and increasing temperatures. It may take a
while to warm up after the very cold morning, but eventually we
should warm above freezing for most areas south of the
mountains.

The next low pressure system will be developing over the Great
Lakes on Monday with our area in the southwest flow ahead of the
broader trough. Thus expect continued warming conditions along
with increase moisture. Models indicate a peripheral shortwave
trough tracking up the East Coast on Monday which will bring an
initial round of rain. There has been some concern that
precipitation could start as freezing rain in colder interior
locations, but it seems the rain is likely to start later in the
day with enough time for the temperature to warm above freezing
for most areas. However, with the recent cold weather there
could be some areas where ground temperatures remain near
freezing and could see icy spots. But for the most part we see
this next system as a rain event area wide as our region will be
in the warm sector of this cyclone. There is still some
disagreement among the models on how fast to send the eventual
cold front through, with the ECMWF remaining on the faster side
of guidance. Still think the GFS is probably handling this
better and has some support from the CMC in moving the front
through Tuesday evening. This means another day of warm
temperatures and rain.

Once the front moves through it will usher in another Arctic air
mass with temperatures tumbling Wednesday and Thursday. The cold
high arrives Thursday night and could bring widespread lows in
the single digits to near zero.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Short Term...MVFR in the mountains tonight with snow showers.
Isolated brief snow squalls possible elsewhere through about 00z
this evening. Otherwise, VFR conditions Friday morning
deteriorate to MVFR Friday afternoon, with a few hour period of
IFR possible, mainly south of a KHIE-KLEW line in light snow.
VFR returns Friday night.

Long Term...MVFR ceilings may linger in the mountains on
Saturday but will finally disperse by Saturday evening as high
pressure builds in. Expect VFR conditions through Sunday.
Ceilings may lower to IFR on Monday as the next low pressure
system brings rain to the area lasting into Tuesday.

&&

.MARINE...
Short Term... SCA will remain in place through tonight as cold
air advection allows for gusts around 30 kt. Another low will
move through Friday afternoon with scattered snow showers
possible along the southern portion of the coastal waters.

Long Term...High pressure crests over the Gulf of Maine Saturday
night into Sunday with a southwest flow developing Sunday
evening. We will likely see gusts to 25 or 30 KT through Tuesday
when the next cold front arrives from the west.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 AM EST Friday for ANZ150-152-154.

&&

$$

NEAR TERM...Ekster
SHORT TERM...Ekster
LONG TERM...Kimble



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