South Portland, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

052
FXUS61 KGYX 211124
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
624 AM EST Thu Nov 21 2024

.SYNOPSIS...
A low pressure system will approach from the Great lakes today,
which will bring widespread precipitation to the region into
Friday. This system will be slow to exit with chances for
precipitation continuing through Saturday. Conditions will start
to dry out Sunday into Monday as the low pressure lifts into
the Canadian Maritimes.

&&

.NEAR TERM /UNTIL 2 PM THIS AFTERNOON/...
Update...
Latest radar imagery continues to show a large band of rain over
New York State and southern New England slowly migrating to the
north and east. This precipitation will take much of the day to
reach easternmost portions of the forecast area which is in good
agreement with the latest NamNest solution.

Have added patchy drizzle to portions of southern Maine and New
Hampshire per latest surface observations. Otherwise, just minor
tweaks to the near term portion of the forecast.

Prev Disc...
Low pressure will intensify off the coast of New Jersey this
morning. This cyclogenesis will accompany the approach of a
large, cutoff, upper level low pressure system. This vigorous
energy will allow for rain to gradually overspread the region
today from southwest to northeast today into tonight. All in all
this will be a delay in the precipitation to reach eastern
portions of the forecast area.

A deep northeasterly flow will develop over the region with a
few gusts exceeding 35 mph which is supported by the latest GYX
probability plots. This raw and chilly flow off the Gulf of
Maine will keep temperatures in the 40s in all regions for
afternoon high temperatures.

&&

.SHORT TERM /2 PM THIS AFTERNOON THROUGH 6 PM FRIDAY/...
The rain will continue to progress to the north and east this
evening as low pressure passes well off the southern New England
coastline and into the open Atlantic. Periods of rain will
continue tonight as the upper level support and a moist
northeast flow continues to impact the region. It will continue
to be windy with lows dropping into the mid 30s north to the
lower 40s south. Atmospheric profiles suggests that some of this
precipitation will accumulate over the higher terrain as it
falls as snow.

Periods of rain will continue on Friday as models remain in
relatively good consensus to keep a large upper level low west
of our forecast area. Temperatures will reach the 40s north to
the lower 50s south.

Despite being a vigorous system, much of the energy arrives in
pieces with this system. Therefore, the overall trend of this
system has been lowered, mainly over eastern areas.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
04Z Long Term Forecast Update...
Latest global forecast guidance and the NBM continues to
indicate that stacked low pressure over the Delmarva on Friday
will drift northeastward towards the Canadian Maritimes by
Saturday night, bringing widespread precipitation to the area.
Thermal profiles support most of this to fall as plain rain
except across the higher terrain and perhaps far western NH
where depending on how quickly cold air wraps around the
departing low, a few flakes are possible. Brief s/wv ridging
looks to arrive on Monday ahead of another area of low pressure
that may bring additional precipitation towards the middle of
next week.

Previously...
Precipitation chances remain high from Friday into Saturday as low
pressure remains over the area, but these will diminish Late
Saturday into Monday as the low lifts northward into the Canadian
Maritimes.

Starting Friday, models are pretty good agreement in a band of
steady precipitation, mainly rain outside the mountains,
continuing to lift northward along an occluded boundary during
the morning hours. Drier air then follows, which should limit
precip to just a chance of showers for the afternoon hours along
with some breaks in the clouds. High temperatures are expected
to reach the mid 40s to lower 50s.

A chance of showers continues from Friday night into at least the
first part of Saturday, and there`s potential to see another
round of steadier precipitation during this time as well,
especially on the western Maine side of the forecast area with
an upper wave moving north from the upper low to the south. The
surface low is also forecast to be deepening while moving
northward over the Gulf of Maine, so Saturday has the potential
to be breezy depending on the track/strength of the low.

The low pressure lifts into the Canadian Maritimes Saturday night
into Sunday with transition to upsloping keeps clouds and rain/snow
showers going in the mountains while the rest of the area sees a
drying trend. Can`t rule out a few showers downwind of the mountains
Sunday, but in general it looks like a breezy day with a mix of sun
and clouds with some daytime instability available. Global models
and ensembles are in good agreement keeping mostly dry conditions on
Monday before another low pressure brings the next chance of
precipitation Monday night into Tuesday.

Highs in the extended are forecast to remain pretty typical for late
November and in the 40s, but some cooler air may start to make it
into the area toward the middle of next week.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
Short Term...VFR trends MVFR for locations that are not already
under MVFR cigs. IFR cigs arrive in southern NH late
early this morning and continue to expand into ME through the
day. HIE may be the only terminal that sees MVFR/VFR as showers
overspread the area today with any precipitation being delayed
at KAUG and KRKD as well. HIE may also experience occasional
stronger gusts due to downsloping in proximity to the Whites.
Northeast winds increase this afternoon, with gusts to 25 kt+
into Thursday night. LLWS is also possible Thursday night.

Long Term...Flight restrictions remain likely from Friday into
at least Saturday for much of the area as low pressure crosses
the region. Ceilings could improve to high end MVFR or even low
end VFR during the day Friday but could again lower to IFR/LIFR
as another round of steadier precipitation potentially arrives
late Friday into the first part of Saturday. This looks to be
mainly rain but could mix in with snow at times away from the
coast. Conditions look to improve Sunday into Monday, but MVFR
ceilings and rain/snow showers remain possible at HIE. Of lower
confidence but worth mentioning: wind gusts of 25 to 30 kt are
possible over the weekend out of the north and northwest, but
that depends on the track and strength of the low.

&&

.MARINE...
Short Term...GYX probability plots suggest a few gusts to 35 kt
or even high will cross the outer waters as the surface gradient
increases later today and tonight. Gales have been posted. Winds
should diminish slightly on Friday.

Long Term...Even though a brief lull in winds is possible over the
waters early Friday, SCA conditions (at a minimum) will likely
continue through the weekend. There also potential for a period
of Gale conditions Saturday into Sunday as deepening low
pressures moves northward near or over the Gulf of Maine into
the Canadian Maritimes, but that is dependent on the strength
and location of the low. A brief improvement is possible late
Sunday or Monday, but another weak low pressure could bring
another period of increased winds and seas around Monday night
or Tuesday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Warning from 4 PM this afternoon to 6 AM EST Friday for
     ANZ150-152-154.
     Small Craft Advisory until 6 AM EST Friday for ANZ151-153.

&&

$$

NEAR/SHORT TERM...Cannon
LONG TERM...Tubbs