882
FXUS61 KGYX 162218
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
618 PM EDT Tue Jul 16 2024

.SYNOPSIS...
Heat and humidity build continue through Wednesday as high
pressure strengthens off the Eastern Seaboard, with chances for
scattered afternoon or evening showers and thunderstorms each
day. A cold front moves through late Wednesday through Thursday,
bringing drier and somewhat cooler conditions for the end of
the week and going into the weekend with high pressure building
in from the west.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
615 PM Update...A Severe Thunderstorm Watch has been issued for
much of New Hampshire into York and Cumberland Counties in
Maine. A well developed QLCS is crossing into southern VT and is
progged to reach the Lower CT Valley around 7 PM. This line of
strong storms has history of producing wind gusts in excess of
70 mph. Latest guidance from the HRRR and WoFS suggest this QLCS
will maintain its strength as it crosses Cheshire and Sullivan
Counties and will start to weaken as it crosses NH into SW Maine
while still posing a damaging wind threat into SW Maine. In
addition to damaging winds, 0-3 km shear orthogonal to the
bowing segment will bring the threat of a QLCS spin up. This
line of storms will reach the ME/NH border around 9 PM and will
move offshore around 10 PM.

Previously...

For tonight, early focus is on developing MCS over central NY
this afternoon, which should strengthen as it moves east, and
move into central/southern NH around 23Z . The timing of this
system is better for severe than last night, but also, it looks
to be organized than last nights system with CAMs developing a
cold pool behind the convective line and possibly a rear inflow
jet. It will likely peak over S VT but the system should
continue to blow itself out as it crosses NH, so some damaging
winds will be possible, and the SPC slight risk area seems like
a reasonable approximation of where the threat is the greatest.
The system should be off shore of ME by 02Z and I dont see any
sever threat beyond this time as well, but a cluster of
thunderstorms will likely continue to move across the N zones
through about midnight. Patchy fog likely develops behind this
line overnight, with lows once again in the mid to upper 60s in
the N and around 70 in the S.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The subsidence and associated sfc high behind this system will
allow for a sunny start a a quick warm up Wed morning, and I
think convection in advance of the front will hold off until
around 18Z. This will allow for another hot and humid with heat
advisories issued over the same areas Tuesday except for
Cheshire county. Showers and Thunderstorms will be more
widespread in the afternoon and evening, and could see isolated
severe storms, with the best chance in southern NH again. Highs
reach into low to mid 90s in the S, with heat index in the mid
to upper 90s. The convection should help knock back the temps in
the mid to late afternoon, and therefore the advisory is only
until 22Z.

Likely wont get to see too much effect from the cold front Wed
night as the front slows around or just S of the CWA and the
threat of showers storms will linger, especially in srn NH and
near the coast through the night, as will the higher dew points
and fog. So lows will rage from the low 60s in the mtns to near
70 again in the S.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
A weak cold front will be in the process of crossing through the
area early Thursday with a continued chance of showers and
maybe a storm or two, mainly in the morning. After that, drier
air behind the front will make for mostly to partly sunny skies
going into the afternoon. There may be a couple of additional
afternoon showers, but the drier air/increasing subsidence aloft
will keep coverage low, and for this reason I have also removed
any mention of thunder during the afternoon hours. More
importantly it won`t be quite as hot with highs staying in the
80s south of the mountains, and dewpoints will also be lower and
in the upper 50s to lower 60s. More comfortable lows are on the
way for Thursday night thanks to the drier air, mostly clear
skies, and light winds. Most should see lows in the 50s with
upper 40s even possible across the northern valleys.

A period of pretty quiet weather is expected from Friday
through the weekend with high pressure largely in control along
with a dry airmass. There will be a chance of showers late
Saturday as a weak cold front crosses through, but this looks
mainly confined to northern areas, and moisture does not look
particularly favorable with this system at the moment. While
temperatures will be "cooler" than what we have been
experiencing lately, highs in the 80s are still forecast each
day, possibly close to 90 degrees for southern areas on Saturday
ahead of the frontal boundary. The silver lining is that
dewpoints will be lower to make the warm temps more manageable,
and temperatures will be able to cool off more at night. We`ll
probably have some valley fog at night/early morning, too.

Mostly dry conditions look to start out Monday of next week,
but after that global models are in pretty decent agreement
showing a broad low pressure approaching the OH Valley/Great
Lakes region. Out ahead of this system, moisture will be on the
upswing, and a warm front lifting northward toward New England
will increase chances for precipitation toward the end of the
forecast period (late Tuesday or even slightly beyond into
Wednesday). This is supported by the GFS/ECMWF ensembles, and
the NBM showing increasing PoPs on Tuesday looks good.

&&

.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
Short Term...Expect a line of potential severe storms to move
through srn NH this evening, affect KMHT/KCON/KLEB, with heavy
rains, frequent lightning and potential W wind gusts to 50 kts
in the 23-01Z period. It is less likely to reach KPSM or KPWM,
but could still see heavy rain and frequent lightning here.
Otherwise patch fog could develop after midnight, especially
where it rained. However VFR returns by 12Z Wed, and should VFR
into the mid afternoon before another round of showers and
storms crosses the area through the evening. Fog and low cigs
will be widespread Wed night with a period of IFR-LIFR possible
at any terminals.

Long Term...Thursday may continue to see some degree of flight
restrictions in the morning with low ceilings a few showers and
storms, but conditions will improve to VFR by the afternoon.
Mainly VFR Friday through the weekend with the exception of
nighttime/early morning valley fog. A weak front approaching
from the north late Saturday could bring a few showers to
northern areas, but this would be primarily for HIE.

&&

.MARINE...
Short Term...SW flow persists tonight into Wed evening, and
could see gusts in the 20-25 kt range, but should stay below SCA
for the most part. Winds will shift to W and diminish Wed night.

Long Term...SCA conditions are not expected. A weak cold front
crosses the waters on Thursday, switching winds to NW to N later
in the day into Thursday night, but these will become onshore
by Friday afternoon as the seabreeze develops. Another weak
front crosses late Saturday and could result in another brief
wind shift to the NW. High pressure then settles over the waters
Sunday into Monday before low pressure brings increasing precip
chances by Tuesday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory until 8 PM EDT this evening for MEZ012-018>024-
     033.
     Heat Advisory from noon to 6 PM EDT Wednesday for MEZ012-
     018>024-033.
NH...Heat Advisory until 8 PM EDT this evening for NHZ004-006-
     008>015.
     Heat Advisory from noon to 6 PM EDT Wednesday for NHZ004-006-
     008>010-012>015.
MARINE...None.

&&

$$


NEAR TERM...Cempa/Schroeter
SHORT TERM...Cempa
LONG TERM...Combs