135
FXUS61 KGYX 210740
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
340 AM EDT Tue May 21 2024

.SYNOPSIS...
High pressure along the East Coast will bring very warm
temperatures to the region through Wednesday. Disturbances
tracking across southeast Canada will bring chances for showers
and thunderstorms today and Wednesday. A cold front approaches
Wednesday night and crosses Thursday for more widespread showers
and storms. Cooler and drier air moves in behind the front with
mostly dry conditions going into the weekend as high pressure
builds in from Canada.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Big sfc high lined up just offshore of the coast, with SW flow
to its N and W and zonal W flow aloft. This spells heat, and it
will be anywhere from 5-10 F warmer today than Monday. Any early
morning stratus should dissipate by mid morning. The sea breeze
still develops as flow will not be strong enough to overcome
the sea breeze today, so highs range from the low to mid 60s
along the immediate coast, especially over the mid coast, closer
to 70 along the coast from Casco Bay S. Meanwhile, inland areas
mostly range from 80-85. For this afternoon will have to watch
approaching MCS crossing S Ontario early this morning, as it
track along the NY/Canada border today. It is likely to weaken
by the time it gets to to the CWA, but, should produce enough
forcing to initiate convection over NH mid to late afternoon. It
will be more scattered and chance will increase as you head you
head N. Still, theres enough instability /CAPE around 1000
J/kg, perhaps closer 2000 depending on what model you believe/,
and deep layer shear of 40-50 kts. This lowers as you head east,
so I think more of the focus for any strong storms will be over
inland NH, and maybe the Western ME mtns. Strong to damaging
wind will be the biggest threat, but could see some hail as
well, as some storms could get a little more organized.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
The t-storms will likely continue into early evening, but the
the treat for severe will drop off quickly around sunset, both
due to loss of heating and the fact the 500 MB wave is weakening
as it approaches. Still the remnant MCS will take much of the
evening to move across the N zones so showers are possible there
until midnight or so. SW flow should keep enough on the boundary
layer to keep temps from falling too much, and the convective
debris will linger overnight as well, so mins will mostly be in
upper 50s to low 60s, but a few degrees cooler on the mid coast
where marine layer will be established. Some patchy fog will be
possible again, with the best chance in the marine layer on the
mid coast, and anywhere it rained this afternoon/evening.

Wednesday will be the hottest day this week with WSW flow
picking up again behind the wave and 850 MB temps pushing up to
near 17 C in the afternoon. SW flow will be fairly strong at the
sfc to prevent the sea breeze from doing much cooling, except at
the beaches. Still the Gulf of ME will have some effect as it
shift the flow a little ore S so the coast will be a little be
cooler than inland, but still temps range from the low to mid
80s on the coast and in the mtns, to around 90 in central and
srn NH. The MCS that falls apart late tonight over N ME could
leave some boundaries in the ME mtns on Wed, so cannot rule out
some isolated convection developing there Wed afternoon, but
this a low chance.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Deep layer ridging in place along the East Coast. Disturbances
rounding the top of the ridge will bring chances for showers and
Wednesday night, mainly across the north. Height falls and the
passage of a cold front will bring more widespread showers and
thunderstorms Thursday. There will be a gradual cooling trend
into the weekend with mostly dry conditions as high as high
pressure over eastern Canada extends into New England.

The two sources of potential impactful weather will be the very warm
conditions Wednesday and Thursday and the chance for strong
thunderstorms Thursday.

Wednesday looks to be the warmest day in this stretch of above
normal temperatures with high pressure stretching from the Southeast
to offshore of New England. Southwest winds along T8s climbing to
+17C will bring highs into the upper 80s to low 90s across the
interior. There will be some onshore wind component that will bring
a marine influence on temperatures near the coast while even here
highs will be near 80 degrees. Favorable mixing will keep
dewpoints in the upper 50s where it will be warmest and
therefore the humidity will not be high enough to bring heat
indices higher than the air temperature. Disturbances moving
atop a mid level ridge will trigger some showers and
thunderstorms mainly across the mountains and north Wednesday
into Wednesday night.

Thursday will be warm again with increasing humidity. A cold front
will cross the area from the west, with some timing differences
amongst the 12Z model suite as to when the front will cross.
Some model solutions have the front sweeping across the area
prior to peak heating around mid day, which will limit the
severe potential. A later frontal passage will allow for better
CAPE juxtaposed with sufficient shear for strong to severe
storms, so will have to monitor the timing of this front over
the next few forecast cycles.

The cold front will be offshore by Friday morning with high
pressure building in from the north through the weekend. This
will bring cooler and drier air into the region for what looks
like pleasant conditions for the holiday weekend.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
Short Term...Fog and stratus has develop[ed along the coast,
with some low stratus at some spots inland, mainly KMHT and KAUG
attm. KPSM is still VFR, and the models were suggesting that
might stay that way overnight. Otherwise, I expect KLEB/KHIE to
fog in at their usual 09Z time, and Im not gonna rule out a
brief sunrise surprise at KCON around this time as well. The
inland flight restrictions should lift around 12Z while coastal
terminals will be more like 13Z. Should VFR through this evening
with the exception of SHRA/TSRA at NH terminals, although best
chance will be KHIE/KLEB mid afternoon through early evening.
Coastal fog/stratus likes to return again later tonight but may
be limited KRKD, and maybe KPWM again. Valley fog at KLEB/KHIE
possible again as well, especially if it rains there.

Long Term...Mainly VFR Wednesday night while some TSRA could
impact KHIE. A cold front crosses Thursday bringing TSRA that
will likely bring periods of restrictions. Drier air arrives
Thursday night allowing for VFR to prevail into Saturday.

&&

.MARINE...
Short Term...SW flow will increase a bit today and may see a few
gusts of 20-25 kt outside the bays this afternoon and evening,
but should stay below SCA conds right through Wed night.

Long Term...Winds and seas remain below SCA thresholds
Thu into the weekend. A cold front will cross the waters
Thursday that will bring chances for thunderstorms over the
waters.

&&

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

&&

$$


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