South Portland, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

731
FXUS61 KGYX 180439
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1139 PM EST Fri Jan 17 2025

.SYNOPSIS...
A cold front will approach the region tonight crossing the area
Saturday. Rain and snow will move through ahead of the front,
with snow accumulating an inch or two in the mountains. Another
wave forms along the front and will track northeastward towards
the Gulf of Maine Sunday night. Snow will spread into the area
to the northwest of the track. Moderate accumulations are
possible. Then Arctic air pours into the country and lingers
through midweek.

&&

.NEAR TERM /THROUGH SATURDAY/...
1130 PM Update... Clouds are continuing to thicken over the
region with earlier cooling now slowed down and in some cases
readings have warmed back up a few degrees. This will be the
theme through the overnight hours with a few flurries possible
across the north and mountains.

Previously...
645 PM Update... Flurries persist across the mtns with
increasing clouds elsewhere and temperatures mainly into the
20s. Just minor adjustments were made at this time based on
latest observational trends.

Previously...
Fairly quiet weather overnight as the primary concerns will be
clouds and temps. Where it remains clear temps will drop quickly
after dark...but any overcast will stabilize readings. So it may
be an overnight featuring bouncing temps hour to hour. Gradually
towards temps should be slowly rising as warm advection
increases ahead of the cold front.

&&

.SHORT TERM /SATURDAY NIGHT/...
Low levels saturate early Sat...with weak lift so it is possible
that some drizzle breaks out early in the day. It is also
possible that higher level saturation provides a seeder-feeder
mechanism. In that case precip would more likely be sprinkles or
flurries. If it tends towards drizzle there could be some
freezing drizzle before temps fully warm above freezing. However
that should remain brief. Maybe a bigger concern is that recent
cold weather will mean cold ground temps and even if the air is
above freezing any drizzle may freeze on contact. With the low
confidence however there are no headlines planned at this time.

By midday the front will move into the area with rain and snow.
Ptype will primarily be based on surface temps...but some light
accumulations are possible in the mtns before the cold front
sweeps thru. It will be the mildest day in a while...with temps
expected to make it into the 40s for a large part of the area.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
05Z Long Term Update... There continues to be rather significant
disagreements between latest deterministic and ensemble based
guidance, particularly in QPF and the location of where the
greatest h7 FGEN forcing will cross on Sunday night. Therefore,
while there is high confidence that it will snow, confidence on
whether we will reach local warning criteria is rather low.
Behind this system there is high confidence for a period of well
below avg temperatures with potentially dangerous windchills.

Previously...
The Greenland block at 500 MB pattern, which has temporarily
broken and shifted toward Europe, seems to want to return again
next week, which will allow for colder air to shift back into
the E half of the CONUS. The only system of note will be the sfc
low that crosses the CWA Sun night into Monday, which helps
pull the arctic airmass equatorward, and ultimately helps to
reestablish the block downstream. But after some SN Sun night,
we turn cold and dry through the rest of next week.

Sunday should start off with at least partly sunny skies, but
clouds will begin to arrive around midday from the SW, and it
will likely be OVC by sunset. Snow will likely begin across S NH
mid to late afternoon, and overspread the rest of the CWA by
early evening. Highs Sunday may actually end up a little above
normal ranging from the mid 20s N, to the mid to upper 30s S,
where temps will get a boost from the NW downslope.

As for the snowfall, the bulk of it will be Sunday night,
probably more in the evening than toward daybreak, but
significant model differences make amounts uncertain. The GFS
and the CMC are both more robust with the QPF, as they tend to
show better phasing with the 500 MB low. However, the ECMWF and
its ensemble still favor and weak phasing and progressive
system, and given the skill of the Euro, Ill lean toward it,
because its been consistent, where some of the models havent
been. Also, the old adage that says when youre in a drought,
forecast a drought, seems to favor sticking with less precip.
Lows Sunday night drop into the teens to low 20s. Monday will
see the colder air begin to work in but the coldest air will
shift in for Tue-Wed.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Largely VFR conditions expected tonight. Some MVFR
CIGs may sneak into the mtns. Clouds will thicken and lower thru
Sat...and eventually IFR conditions are expected as precip moves
into the area. A period of LLWS is also possible...especially
early Sat before warmer air can mix inland. IFR conditions are
expected to continue into Sat evening when winds shift westerly
and VFR returns south of the mtns.

Long Term...IFR or lowers expected late Sunday and Sunday night
in SN, but should improve to VFR Mon morning. Then mainly VFR
though Wed, although KHIE may see some restrictions in upslope
conds.

&&

.MARINE...
Short Term...Light winds expected tonight but southerly flow
will begin to increase Sat. SCA conditions will develop in the
morning...but gale force gusts outside of the bays possible thru
the evening. Winds and seas will gradually diminish after
midnight.

Long Term...SCA conditions likely Sun night through Tue with
light freezing spray increasing on Monday and continuing into
mid-week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Warning from 10 AM to 10 PM EST Saturday for ANZ150-152-
     154.
     Small Craft Advisory from 7 AM Saturday to 1 AM EST Sunday for
     ANZ151-153.

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Legro
LONG TERM...Cempa/Tubbs