760
FXUS61 KGYX 182234
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
634 PM EDT Thu Jul 18 2024

.SYNOPSIS...
Much drier air will continue to filter into the region through
tonight with temperatures in many locations falling to the
coolest values in over two weeks. A dry and seasonable pattern
is expected through the upcoming weekend and into early next
week. Outside of a few mountain showers Saturday night...the
next chance for precipitation across the area does not arrive
until next Tuesday in the form of showers and thunderstorms
ahead of a cold front.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
630 PM Update...Very little change to the going forecast. A fair
weather night will be hard with diminishing winds with low temps
and dewpoints lower than previous nights. Late valley fog is
likely.

Previously...

The long-awaited drier airmass has arrived in the wake of the
cold front that crossed the area this morning. Dewpoints are
currently in the 50s for most of the area with the exception
being Augusta and Midcoast regions, where dewpoints are still
holding in the 60s. A couple of light showers will be possible
later on this afternoon into early this evening, mainly across
far northern areas with dry conditions across the rest of the
area.

Going into this evening and tonight, the cu field will diminish
and with winds becoming light, the mostly clear skies will allow
temperatures to cool off nicely. The dewpoints will be a pretty
good proxy for lows with coastal areas ranging from the upper
50s to lower 60s with most in the 50s across inland areas. A few
of the northern valleys could reach the upper 40s if it stays
clear enough, but some guidance is showing a slight increase in
cloud cover across the north, potentially limiting cooling.
Regardless, it will be a stark difference from the last couple
of weeks.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
The much drier, subsident airmass will be fully in place on Friday
with high pressure over the region. As a result, skies will be
mostly sunny with no rain in the forecast. While it still be warm
out (highs in the low-mid 80s south of the mountains), it won`t be
nearly as humid with good mixing, which will bring afternoon
dewpoints down into the low-mid 50s.

Winds will become light in the evening and persist into Friday
night, and with clear skies, good radiational cooling is forecast. A
few southern/coastal areas may stay closer to 60 degrees for lows,
but in general overnight lows are expected to be in the 50s and even
into the upper 40s in some of the northern valleys. Patchy valley
fog is also possible.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
High Impact Weather Potential: Minimal through early Tuesday.
Chances for showers and thunderstorms increase for Tuesday-
Thursday though confidence is low on any severe weather/hydro
threats at this range.

--Pattern and Summary--

The longwave pattern is expected to remain rather stable through the
long term forecast period with a substantial longwave ridge located
along the spine of the Rocky Mountains with troughs on either side
of this over the eastern Pacific and eastern North America. This
will keep the flow aloft generally from the west northwest or west
with H5 heights and T8s pretty close to...or just above seasonal
norms.  Through early next week...the modified Canadian airmass will
keep the weather quiet and dry.  By the middle of next week...the
eastern trough will reload as energy drops into the Great Lakes
region...allowing our flow to back southwesterly and allow a frontal
system to move through the region to end the forecast period with
what will likely be the most active portion of the forecast weather-
wise.

--Daily Details--

Saturday through Monday: The period opens with westerly flow aloft
ahead of a southward-sinking cold front.  Temps aloft will be
warm...reaching +14-16C which would support highs in the lower 80s
in the mountains with mid/upper 80s to the south and east. The cold
front crosses the area Saturday night with a few mountain
showers....but frontal timing and thinning moisture plume suggests
little overall rainfall. Drier and somewhat cooler air sinks in from
the north for Sunday...with decreasing clouds and mountain high
temperatures in the 70s. Further south...T8s won/t change too much
from on Saturday...and therefore 80s are again expected for highs.
The drier airmass will allow for more substantial cooling Sunday
night with some mountain valley locations likely reaching the upper
40s while 50s to just above 60 is likely further south. High
pressure remains in control through Monday with some weak
moisture return as the flow aloft begins to back ahead of the
next shortwave/cold front dropping into the Great Lakes region.
Generally neutral temperature advection should allow for similar
daytime highs...mid/upper 70s in the mountains and 80s to the
south.

Tuesday through Thursday: The second half of the long term forecast
turns more active as the eastern trough initially reloads over the
Great Lakes...with a positive tilt allowing the flow over the
northeast to turn more southwesterly...allowing for building
moisture.  A weak front dropping into the region Tuesday may spark
some showers and thunderstorms with this trend continuing through
Wednesday as the flow remains generally parallel to the front
causing it to stall and service as a llevel focus for lift.  Global
ensembles differ on the eventual evolution of the upstream
positively tilted trough across the Mississippi Valley and
additional shortwave energy diving out of Canada.  With the
likelihood that the overall trough axis remains west of our
longitude through Thursday will necessitate a continuation of
shower/storm chances with building humidity but temperatures close
to seasonal norms with clouds and precipitation potential.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Short Term...A couple of light showers may develop through the
duration of the afternoon, but coverage is much too low for any
TAF inclusion. Otherwise predominantly VFR through Friday night,
but valley fog may develop tonight and again Friday night,
potentially impacting HIE and LEB.

Long Term...
VFR conditions should persist through Tuesday morning with some
morning fog possible each morning at HIE/LEB.  Tuesday afternoon
will bring a chance of restrictions given a chance for showers and
thunderstorms.

&&

.MARINE...
Short Term...SCA conditions are not expected through Friday
night. High pressure builds toward the region tonight in the
wake of the cold front that crossed the waters early today. This
will shift winds to N/NW this evening, which will stay through
Friday morning. These will switch back to more onshore by Friday
afternoon with the development of the seabreeze and high
pressure becoming centered south of the waters. Light southwest
flow continues through Friday night.

Long Term...Winds/waves are expected to remain below SCA levels
through the long term forecast period Saturday-Tuesday.
Thunderstorms are possible over the waters by Tuesday afternoon.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...Ekster
SHORT TERM...Combs
LONG TERM...Arnott
AVIATION...
MARINE...