557
FXUS61 KGYX 261921
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
321 PM EDT Sat Apr 26 2025

.SYNOPSIS...
Low pressure crosses the region tonight and lingers in the Gulf
of Maine Sunday bringing rain and some high elevation snow
across the north and showers south of the mountains. High
pressure builds in Monday and Tuesday for fair weather and
temperatures in the 60s and 70s. The next frontal system crosses
Tuesday night with high pressure building in the second half of
next week.

&&

.NEAR TERM /TONIGHT/...
Latest water vapor imagery shows a compact upper low over Ontario
with this feature forecast to cross Upstate NY tonight and into the
Gulf of Maine Sunday. At the surface, low pressure centered over
Vermont will advance east with the main axis of rainfall exiting the
coast and eastern zones over the next couple of hours. Upstream
there are some breaks in the cloud cover. Recent CAM guidance
suggest that some filtered insolation will allow for a corridor
of MU CAPE up to 500 J/kg to develop across southern NH and SW
Maine before sunset. While much of the area will see a downward
trend in PoPs through this evening, the corridor of instability
will bring chances for showers and thunder across southern NH
this evening.

Tonight dry air aloft will work into areas south of the mountains
while the surface tracks along the coast of Maine. This may allow
for clearing skies across southern NH and SW Maine while low clouds
and fog persist along the coast into central Maine. As low
pressure deepens along the coast later tonight a deformation
zone will bring increasing chances for precipitation over the
mountains. Lows tonight will range from the upper 30s across the
north to the upper 40s near the coast.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
Low pressure will slowly move through the Gulf of Maine Sunday
while the upper low crosses overhead. This will make for a
cloudy and cool day with showers south of the mountains. As the
upper low crosses overhead, temperatures will cool aloft with
T8s dropping to around -4C over the mountains. This will allow
for rain across the north to change to snow in the mountains
with a few inches of snow possible above 3KFT. If precipitation
rates are intense enough some snow may mix with rain all the way
to valley floors across the north. As the system pulls east of
the area NW winds will increase during the afternoon with gusts
25-30 mph. Highs will range from around 40F across the north to
near 50F across the south.

Chances for precipitation diminish Sunday evening with drier air
working into the area overnight. This will lead to clearing
skies and lows ranging from the mid 30s north to low 40s south.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Key Message: Upper ridging to start the period will gradually give
way to more trofing over time. Heading into next weekend the pattern
will become more blocky and exactly where cutoffs form will largely
determine our sensible weather.

Impacts: No significant weather anticipated. There may be a day or
two will low dewpoints and low RH values but after a good soaking
today and enough chances for rain in the extended fire weather is
not a large concern.

Forecast Details: To start the period upper ridging and an
approaching cold front will keep winds largely from the
southwest. It is a warm pattern and ensemble guidance agrees
that Mon thru Wed should be the warmest days of the
extended...likely peaking on Tue. That looks like a widespread
70s except near the coast where winds will likely try and turn
onshore by afternoon. Southwest winds may keep it relatively
pinned to the coastline south of PWM...but sea breeze could make
a run inland across the Midcoast.

Will also be watching the timing on the front Tue. Currently set
to arrive after peak heating and instability will be
waning...but if model guidance speeds things up there may be a
need to add some thunder to the forecast. Widespread precip
with this front will be lower confidence...especially as it
nears the coast.

There is a stronger signal for precip over the weekend...as
trofing deepens over the East Coast. Initially a warm front
will lift into the Northeast and then surface low pressure will
strengthen and track thru. The GEFS and ECMWF ENS are both
pretty bullish on rain chances with the GEPS drier. Fairly
widespread likely PoP from the NBM seems fair to me at this
range...so I did not change that forecast.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Short Term...Low cigs and reduced visibility in -SHRA and BR
will bring IFR/LIFR to KPWM, KAUG, and KRKD tonight. Some drier
air moving in from the west will allow for mainly MVFR at
remaining TAF sites tonight. Low cigs will linger through Sunday
with most sites seeing MVFR for prevailing conditions, although
some VFR may be achieved at times. Conditions improve to VFR
Sunday night.

Long Term...VFR conditions expected to prevail for most of the
period. Outside of local MVFR or lower conditions in SHRA with
the frontal passage Tue night I do not anticipate much trouble
with CIGs or VIS. Southwesterly LLJ will strengthen Tue night
but largely unidirectional flow should preclude LLWS.

&&

.MARINE...
Short Term...Low pressure crosses New England tonight and into
the Gulf of Maine Sunday. This system will bring SCA conditions
that last through Sunday night.

Long Term...Marginal SCA conditions are possible Wed as a cold
front approaches the waters. The best chances are well outside
the bays. Southwest winds this time of year tend to be weaker
than forecast with the cold SSTs...so I did knock down speeds by
2-3kt and even then the seas may be too high as well.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 AM EDT Monday for ANZ150-152-154.
     Small Craft Advisory until 2 PM EDT Sunday for ANZ151-153.

&&

$$


NEAR TERM...Schroeter
SHORT TERM...Schroeter
LONG TERM...Legro