-- Discussion containing changed information from previous version are highlighted. --
911
FXUS61 KGYX 220352
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1152 PM EDT Tue May 21 2024

.SYNOPSIS...
Scattered thunderstorms are expected across New Hampshire and
interior Maine through this evening, with a few strong to severe
storms possible. Very warm and increasingly humid conditions
will follow through Thursday. A cold front will cross Thursday
and will bring potential for thunderstorms with the potential
for a couple to become strong to severe. It will remain warm
Friday into the weekend weak systems bringing low chances for
showers late in the weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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1145 PM Update... Remnant and weakening convection is crossing
over the CT River Valley into NH with a cold pool helping to
maintain this region of light to moderate rainfall and
occasional lightning. There remains some uncertainty in how far
east this area of rain will make it into NH and possibly
western ME as latest CAM runs continue to struggle but no
further strengthening is expected as this activity remains
elevated in nature. Nevertheless, did increase PoPs to account
for this rain and made some minor adjustments to
temperatures/dewpoints through the overnight hours. Patchy fog
is already beginning to develop as well and it could become
locally dense so please use caution if traveling.


800 PM Update... An area of thunderstorms is continuing to
weaken as it moves east over the Seacoast of NH as it interacts
with the marine layer and a stout inversion. There is another
area of convective showers over Coos county NH but decreasing
shear and increasing CIN is helping to keep this weak. This will
continue to be the trend over the next few hours as the threat
for severe storms has ended. The main changes with this forecast
update were to tighten up PoPs as well as remove enhanced
wording from the forecast.

Previously...
A convectively induced short wave associated with a remnant MCS is
tracking across southern Ontario this afternoon. This wave has
already triggered convection across Upstate NY and VT that has
spilled into NH. The 12Z HREF suggests that thunderstorms cannot be
ruled out across the entire area while the best juxtaposition of
shear and CAPE will be across NH and to a lesser extent into the
western Maine mountains. Latest RAP analysis shows ML CAPE is now up
1000J/kg and will build up to 1500J/kg across southern and western
NH with effective shear to 25-30 kts. Farther east, cool onshore
flow will limit instability across the NH Seacoast and along the
coastal plain of Maine. CAMs generally fire storms through 00Z with
convection waning afterwards. A notable trend within the 12Z CAM
suite has been for increased coverage in storms across southern NH
and interior SW Maine with these storms holding together as the
approach the coast. Both strong to damaging winds and marginally
severe hail will be a threat with storms with the greatest
threat for strong storms across central and southern NH where
the best instability will be.

Tonight will be mild and humid with patchy fog likely along the
coastal plain and interior valleys. The will be lingering
instability overnight that could allow for isolated
thunderstorms across the north. Lows tonight will be in the
upper 50s to low 60s.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Wednesday looks to be the warmest day of the week with highs in
the upper 80s to low away from the coast and south of the
mountains. Mid level ridging will try to build over the area
while disturbances traversing to top of the ridge will bring
chances for showers and thunderstorms across the north.
Southwest to south winds will advect some cooler marine air into
the coast that will keep highs here in the 70s to near 80
degrees.

Wednesday night will be warmer than tonight with lows only
dropping into the low to mid 60s. An approaching cold front will
bring increasing chances for showers, and perhaps some thunder
across northwestern zones by Thursday morning.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A shortwave stemming from an upper low north of the Great Lakes is
set to cross New England during the day Thursday while sending a
cold front through. This front will provide focus for showers and
storms during the day as the environment out ahead it will be warm
with temperatures in the 70s and 80s, and dewpoints will be in the
mid 50s to lower 60s. A few strong to severe storms are not out of
the question as bulk shear could surpass 30-35 kt while temperatures
aloft will be cold, supporting the potential hail, and low-level
lapse rates will be steep, supporting locally strong to damaging
winds. However, the timing of the front is key here, and if it
is quicker to move through, then the overall threat will be
lower for strong/severe storms.

Skies quickly clear out behind the front Thursday evening into
Thursday night as drier air works into the area. Overnight lows
remain mild with mid 50s to lower 60s expected. It`s possible some
of the valleys see fog develop late and toward daybreak, and if any
develops it should quickly clear up within an hour or two after
sunrise. The dry air stays around for Friday providing mostly sunny
skies with no rain in the forecast. It will again be quite warm with
temperatures reaching the upper 70s to mid 80s away from the
coast.

The warmth continues over the weekend, but a couple of weak waves
aloft will cross the area, bringing a chance of showers each day.
With how things look right now, the higher shower chances will be
across the interior and farther north and mainly during the daytime
hours. High temps are forecast to reach the 70s to low 80s for much
of the area, but prevailing southerly flow/seabreeze will keep
things cooler along the coast. Will also have to watch for marine
fog/stratus during the nighttime hours.

The next opportunity for more widespread precip arrives early next
week as global models are in decent agreement showing a more
amplified trough and potentially a deepening coastal low moving into
the Northeast.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Scattered TSRA will bring potential for brief
restrictions with the greatest chance for TSRA at KLEB and KCON
and cannot be ruled out at KHIE, KMHT, and KPSM. There will be
patchy fog tonight that will bring potential for IFR along the
coast and CT Valley. Mainly VFR is expected Wednesday with
potential for patchy fog again Wednesday night.

Long Term...Marine fog/stratus may produce IFR/LIFR conditions into
Thursday morning, but this would be more likely at RKD. Otherwise, a
cold front will bring another chance of showers and storms from late
Thursday morning into the afternoon with the highest potential
generally south and east of a LEB-AUG line. These will be
capable of brief instances of IFR to MVFR restrictions, but
conditions should remain VFR outside of precipitation on
Thursday. Drier air and high pressure brings mostly VFR Friday
into early Saturday, but another low pressure will bring more
chances for showers and flight restrictions the rest of the
weekend. Southerly flow will also keep the potential of marine
fog/stratus for the coastal sites over the weekend.

&&

.MARINE...
Short Term...Winds and seas remain below SCA thresholds tonight
through Wednesday night. There will be scattered thunderstorms
over land through this evening that will approach the waters
around sunset with storms expected to weaken as they move into
the waters.

Long Term...South to southwest winds will precede a cold front on
Thursday, with fog remaining a threat prior to the front`s passing.
The front is currently forecast to cross the waters by late
afternoon or early evening with a wind shift to northerly into
Thursday evening/night. Winds are expected to remain below SCA
levels. Additional weak low pressures will move through over the
weekend and with southerly flow generally remaining, will probably
see additional fog over the waters.

&&

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

&&

$$

NEAR TERM...Tubbs