969
FXUS61 KGYX 201835
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
235 PM EDT Sat Jul 20 2024

.SYNOPSIS...
A cold front drops south tonight through Sunday, bringing the
chance for scattered showers and a stray thunderstorm.
Otherwise, mostly dry conditions continue into Monday. Moisture
increases Tuesday with daily chances for showers and afternoon
thunderstorms into Friday. Cooler conditions are expected for at
least Wednesday and Thursday. High pressure looks to return for
next weekend with warming temperatures.

&&

.NEAR TERM /TONIGHT/...

High Impact Weather Potential: Minimal.

Pattern: Quiet weather this afternoon with some high cloudiness
across the area.  Potent surface cold front sits north of northern
New England associated with low pressure across northern Quebec and a
strong upper low east of James Bay.  While the mid and upper low
continue to push east...northwesterly llevel flow at H8 will drive
this front towards the international border after midnight and into
our the mountains through daybreak. Thus..the forecast focus will be
on whether this front can spark and showers and the impacts of
associated clouds on overnight lows.

Through this evening: Quiet weather is expected through the evening
with clouds along the surface cold front nearing the international
border by 8pm with mostly clear skies south of this outside of some
cirrus esp over the southern half of the area. Temperatures will
fall back into the upper 60s in the mountains by 8pm with 70s
elsewhere.

Tonight: Moisture plume with PWATs to around 1.25" drops into the
mountains tonight ahead of the surface cold front with the front
beginning to outpace mid level support with instability diminishing
through the overnight.  The result should be a decaying line of
showers reaching the far northern zones overnight with the surface
wind shift pushing ahead of the moisture boundary to the coast.
Outside of the northern showers...expect partly to mostly cloudy
skies...which should keep overnight lows a bit warmer than the
previous night...with values in the upper 50s in the mountains and
lower to middle 60s to the south.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
High Impact Weather Potential: Minimal.

Pattern: Surface front draped across the region Sunday morning will
cross the area through the day providing a focus for clouds and some
possible showers.  Beyond this...drier air drops into the region
Sunday night with quiet weather and cooler overnight lows expected.

Sunday: Moisture boundary associated with the cold front will
continue to drop south through the region...with modest MLCAPE of a
few hundred J/kg developing from the foothills to the coast.
Mesoscale ensemble guidance indicates the potential for a few
showers to form along the advancing boundary /and possibly a rumble
of thunder/...but not expecting much in the way of shower
coverage. T8s will range widely from north to south...only
around +10C in the north to +15C in the south. The result will
be highs only around 70 in the mountains... while over
southeastern NH...upper 80s will again be possible...with
lower/middle 80s elsewhere into the foothills.

Sunday Night: PWATs fall to around 0.5" with surface dewpoints in
the 40s behind the departing cold front.  Given mid level height
rises and a surface high pressure axis moving overhead...expect
mostly clear skies with temperatures falling into the 40s across the
mountains...with lower 50s from the coast into the foothills.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Overview...

A ridge builds into the Northeast as a near stationary front
begins to drift northward through midweek. Increasing moisture
from the building ridge brings increasing chances for showers
and thunderstorms by Tuesday and Wednesday as the moisture
interacts with the front, with shower chances continuing into
Thursday and Friday. A stronger cold front pushes through late
in the week, with high pressure building into the weekend and
bringing drier conditions.

Details...

Monday looks to be mostly dry as the front makes its farthest
south progression, leaving northern New England on the dry side
of the front. By Tuesday, the front begins to drift northward
as a warm front, likely extending through the forecast area by
the afternoon hours. Scattered showers and storms become more
frequent by the afternoon hours near the front, but the exact
location of the front at this time remains uncertain.

Overall, the progression of the weather features have been
trending slower on the ensembles as we get closer in time. This
continues a trend we have seen over the last few weeks, and is
not uncommon in the summertime as forcing and features are not
as well defined compared to the cooler season. So currently
central and interior areas look to see the most widespread
showers and storms on Tuesday, but this will likely still need
to be fine tuned over the next couple of days depending on the
progress of the front.

Scattered showers and cooler conditions are expected for
Wednesday as the front lingers and mostly cloudy skies are
expected. By Thursday, a weak wave of low pressure likely moves
along the front and helps to enhance the shower and storm
activity. This looks like the best chance for the threat of some
heavier rainfall, especially in any areas that get worked over
in the previous couple of days.

Friday is where the slowing of the weather pattern since
yesterday shows up most, with chances for showers continuing.
Should the speed of the low`s progression be slower, Friday
could end up even wetter. With it still being almost a week
away, it`s too early to sort out any details with this feature,
but the trend for now is that it would be slower to depart. Then
by next weekend, high pressure begins to build in from the west
behind a more well defined cold front that helps clear out the
moisture. Temperatures also begin to rise again by next weekend
with this increasing sunshine.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Short Term...

Summary: A cold front crosses the region from north to south late
tonight and Sunday with clouds and a few showers before much drier
air moves into the region with clearing skies late Sunday and Sunday
night.

Restrictions: VFR conditions are expected to dominate the period
through Sunday night. Increased cloud cover tonight will likely
limit fog development except at LEB where there is potential for
fog just before daybreak. Any shower activity is expected to be
light and...while some localized restrictions are possible...
confidence is not high enough to include mention of them in this
afternoon/s TAF package.

Winds:  Outside of a robust seabreeze for coastal locations...
southwest winds around 10kts will gradually diminish with all sites
5kts or less for the overnight.  Winds become northwesterly and
increase to 8g15kts for the day on Sunday with some potential
for a seabreeze again at PSM. Winds go calm/light-variable
Sunday night.

LLWS: LLWS is not expected through Sunday night.

Lightning: There is a very low /20%/ potential for thunder at
CON-PWM-AUG Sunday afternoon.

Long Term...Mainly VFR conditions are expected on Monday, and
then intermittent chances for restrictions with afternoon
showers and storms return for Tuesday through Friday. Periods of
marine fog and IFR conditions are also possible through coastal
terminals during this time period. Conditions likely improve
next Saturday as high pressure brings more steady VFR
conditions.

&&

.MARINE...
Short Term...Winds and waves are expected to remain below SCA
levels through Sunday night.

Long Term...A front stalls across the Gulf of Maine and lingers
for much of the week. Pressure patterns remain weak most of the
week, keeping conditions below SCA levels. Areas of dense fog
are possible at times Tuesday through Friday as the front
lingers. High pressure then clears the fog by next weekend.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$


NEAR TERM...Arnott
SHORT TERM...Arnott
LONG TERM...Clair
AVIATION...Arnott/Clair
MARINE...Arnott/Clair