Area Forecast Discussion
Issued by NWS Portland, ME

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KGYX 202352
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
652 PM EST Mon Nov 20 2017

.SYNOPSIS...
Axis of cold high pressure slides east across New England
tonight, with a warm up expected on Tuesday. The next cold front
will arrive on Wednesday with a chance of mixed precipitation in
the mountains and rain along the coast. This front will bring a
return to cold conditions which will last through the upcoming weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Update...
Scattered snow showers and flurries continue to cross over the
mountains and foothills region. A few flurries may be making it
to central and southern areas late this evening, however any
precipitation will be very light as sublimation occurs.

Lowered temperatures in the mountains as they are already near
or at their forecast lows. Added some additional cloud cover to
the forecast for the rest of this evening based on latest
satellite imagery. Otherwise, one last cold night before the
warm air advection begins and temperatures climb to above normal
for this time of the year on Tuesday.

Prev Disc...
Winds have been a bit gustier than anticipated earlier today,
however the gusts are beginning to lessen as the pressure
gradient relaxes. One final round of light snow coming from a
mid level cloud deck will move east and out of the forecast area
this evening. Ridge axis slides by tonight allowing winds to go
nearly calm before returning southerly in the morning. A warm
front will move through aloft bringing some clouds and warmer
temperatures. For tonight`s lows we had to consider the very dry
starting conditions and the likelihood of calm winds leading to
at least a few hours of good radiational cooling particularly
in the northeast part of the forecast area. But cloud cover
arriving overnight will halt the cooling at least for half of
the area, with temperatures holding steady or slowly rising by
morning. Expecting mostly 20s tonight, but some teens are
expected in the valleys of northwest Maine.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Much warmer temperatures can be expected on Tuesday as a warm
front lifts north of the area, putting us fully within the warm
sector of the approaching wave. Fairly strong southwesterly low
level flow will also aid in downslope warming to the east of the
mountains. We are going with high temperatures in the 50s
tomorrow, which represents mixing up to about 925 MB. Even
warmer air exists above that, and if we were to mix to 850 MB
temperatures in the 60s would be observed. However, mixing to
850 MB is tough to do this time of year only one month away from
the winter solstice. Thus low to mid 50s seem the most
reasonable for tomorrow. Southwest winds will be breezy again,
but not as windy as the past few days. A few gusts to 30 MPH are
not out of the question.

With the cold front approaching from the west the pressure
gradient will remain tight enough and clouds will increase
enough to prevent strong cooling overnight. Lows will drop only
into the 30s for most areas, though a few upper 20s are also
possible in the colder north. The front will be knocking on the
doorstep of New Hampshire and the Canadian border of Maine
around dawn with a line of showers possibly forming along the
front. This may take the form of a brief squall, but overall
precipitation amounts would be light considering the lack of a
good moisture connection with this system... yet.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long term period is dominated by fast flow across the region
with fairly dry conditions for much of the period.

A cold front will cross the region Wednesday. Although the models
agree that the front will cross the region, models differ on
the timing of the front and the effect of Atlantic moisture
streaming northward ahead of the front. GFS and NAM keep this
moisture off the coast while ECMWF brings it inland. Have used a
blend of models across coastal areas with the likelihood of
some morning showers across coastal areas. In the mountains,
precip type is a bit questionable early Wednesday with
temperatures near freezing but any precip should turn to snow
showers as colder air moves into the region during the morning
hours. Any snowfall accumulations in the mountains should be
light.

The front moves east Wednesday afternoon with any remaining
showers ending early afternoon across the midcoast. High
pressure builds across the area Thursday with another weak front
crossing the area Thursday night or Friday morning. High
pressure slips south of the region during the day Friday with
another weak front crossing the area Saturday.

The generally dry northwest flow is expected to continue into
early next week.

After Wednesday morning, the greatest chances for any
precipitation will be in the mountains with the passages of
cold fronts.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Short Term...Gusty west northwest winds will diminish this
evening with VFR conditions continuing. A southwest breeze will
commence tomorrow. A cold front approaches from the northwest by
Wednesday morning.

Long Term...MVFR to IFR conditions possible Wednesday morning
across coastal areas. MVFR to IFR conditions possible in
mountain snow showers Wednesday. Otherwise...mainly VFR
conditions expected.

&&

.MARINE...
Short Term...The pressure gradient will continue to relax
enough to allow gusts to fall off. Have therefore, discontinued
the gales. With the offshore flow, wave heights will be
greatest further from shore. Winds become southwesterly on
Tuesday and will likely reach solid Small Craft Advisory
criteria.

Long Term...SCA conditions will persist in the offshore zones
for much of the period in mainly northwest flow.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 5 AM EST Tuesday for ANZ150>152-154.

&&

$$
JC



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.