511
FXUS61 KGYX 171435
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1035 AM EDT Fri May 17 2024

.SYNOPSIS...
A weak trough will approach northern areas today bringing
scattered showers to the mountains. This system will bring
scattered showers to all areas on Saturday before exiting east
of the region on Sunday. High pressure strengthens over the
region early next week with dry conditions and much above normal
temperatures. Scattered showers return by late Wednesday into
Thursday as a cold front approaches and then crosses the region.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

1035 AM Update...Not too much change to the going forecast. Re-
timed PoPs for this afternoon with latest hires guidance, but
same thinking holds with heating expected to touch of some
showers in the Western Maine Mountains and northern New
Hampshire later this afternoon. Otherwise, fog has dissipated
and clearing skies have resulted in some quick warmups for some
interior areas. Smoothed out these observed trends in
temperature, dewpoint, and sky cover to get us through the
afternoon.

PREVIOUS DISCUSSION...
630 AM Update...Little change to the going forecast. Still
seeing some locally dense valley fog at this hour, but due to
the fairly confined nature have opted to not issue an SPS as
conditions will improve over the next hour so.


Mostly clear skies and little to no wind has resulted in a fair
amount of valley fog early this morning, which can actually be
seen on satellite this time around. Some of it will be locally
dense but most of this will dissipate within a couple hours
after sunrise.

For the rest of the day, weak high pressure will be draped
across northern New England resulting in mostly dry conditions
and partly sunny skies, but clouds will start increasing later
in the afternoon as a trough approaches from the west. The
exception will be across the northern half of the area, where
isolated to scattered showers are expected as there still be
enough moisture and around 100 J/kg of CAPE. These will then
fizzle out as we approach sunset. For highs, the MAV guidance
has had a cool bias for the last several days, so I have played
the persistence card and went slightly above this, which puts
highs in the low- mid 70s, except for 60s at the coast.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
Clouds continue to increase tonight with the approach of the
mid-level trough and as higher moisture streams northward
stemming from the same area of low pressure that has been
lingering to our south the last couple of days. Patchy fog will
be possible again across the interior, and marine fog may move
ashore on the coast this evening and tonight, but models have
really struggled on this so I`m not super confident about it.

We could start seeing showers overnight and toward daybreak
along and inland from the coast, per the NAMnest and HRRR, but
confidence is low as other models keep dry conditions through
the night. Overnight lows will be in the mid 40s to lower 50s.

Going into Saturday, mostly cloudy conditions remain in place
through the day with the potential for showers across the area
with the approach of the 500mb trough and the other disturbance
approaching from the south. Model guidance remains in poor
agreement, and due to this I have taken a "middle of the road"
approach to rain chances with 40-60% across the area. Some areas
will likely see chances come up in future forecasts (potentially
by quite a bit) while others see a decrease, and hopefully
today`s 12Z guidance paints a clearer picture. I have also
lowered temperatures some with generally low- mid 60s, but
around 70 degrees is possible toward the CT River Valley.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
An upper level low pressure system will continue to exit to our
east Saturday night. Any leftover showers will begin to diminish
during the evening hours. Temperatures will drop into the 40s
with patchy fog forming across portions of the interior valleys.

As the upper level low continues to shift to the east on Sunday,
high pressure will strengthen over the region. The most sunshine
will occur over northern and western portions of the forecast
area, with the most cloudiness accordingly over southern and
eastern areas closest to the departing feature. As height rises
continue, expect warming to occur with 70s across western Maine
and New Hampshire. The exception will be along the coast with
sea breezes limiting daytime temperatures to the 60s.

Height rises will continue on Monday and Tuesday with the
surface ridge gradually shifting to our south. Warm air
advection will allow for 70s across the interior once again on
Monday with some readings above 80 degrees over southern and
western New Hampshire. Sea breezes will return to the coastline
during the daytime heating. 00Z operational models and ensemble
solutions suggest that Tuesday will be the peak of the warmth
with H8 temperatures approaching +14C in a well mixed
environment and continuing dry conditions. This will allow for
lower 70s along the coast and readings in the 75 to 85 degree
range across the interior. Again, the vast majority of the
region will continue to remain dry, however a shower or
thunderstorm will be possible near the Canadian border as a
front will be nearly stationary over southern Canada.

The warmth continues into Wednesday. However, winds will begin
to back to the south as a large scale system approaches from the
west. Scattered showers will begin to enter the region late
Wednesday and continue into Wednesday night as low pressure
crosses through southern Canada and moisture ahead of a cold
front enters our region. This front will cross the region
Thursday with scattered showers and possibly a rumble of thunder
in the north. A few of the showers may be locally heavy with
plenty of moisture in the atmosphere and precipitable water
values rapidly climbing.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Short Term...Fog that does develop will bring restrictions to a few
sites, but this will dissipate by 11-12Z for inland sites while
taking longer at the coastal sites, should it develop near the
coast. VFR then expected the remainder of today with most showers
expected to remain north of the TAF sites. If any site were to get a
shower it would be HIE and AUG, but potential is much too low for
TAF inclusion. For the coast, marine fog/stratus should remain just
offshore most of the day, but could start to creep back inland by
early this evening but more so tonight. Potential for MVFR to IFR
ceilings along with showers increase overnight and Saturday, but
confidence in details is low.


Long Term...Some MVFR ceilings are possible into Saturday
evening as a weak system exits the area and scattered light
rain showers diminish overnight. Otherwise the rest of the
period will be VFR with light winds as high pressure builds in
through Wednesday morning. Ceilings begin to lower late
Wednesday through Thursday in scattered showers.

&&

.MARINE...
Short Term...With the exception of the afternoon seabreezes, winds
will be primarily out of the E/NE today and Saturday as low
pressure stays south and east of the Gulf of Maine. These winds
may increase enough during the day Saturday to bring a period of
SCA conditions over the outer waters.

Long Term...SCAs may be needed over the weekend as low pressure
passes over the waters and brings seas to around 5 ft.
Otherwise, high pressure builds in for next week which will
bring conditions back below SCA thresholds and keep them there
through this forecast period.

&&

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

&&

$$

UPDATE...Baron
NEAR/SHORT TERM...Combs
LONG TERM...Cannon