172
FXUS61 KGYX 101130
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
730 AM EDT Wed Jul 10 2024

.SYNOPSIS...
A trough approaches from the west today transporting remnant
moisture from Beryl into the region through Thursday morning.
Thunderstorms are again possible Friday as a stalled remains
over the region. A few more scattered showers and storms are
expected over the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
630 AM...Despite all that`s going on, forecast seems in pretty
good shape for today. Just made some tweaks to temps/sky based
on current obs. Max T still a bit of an uncertainty, as there
are a lot of mid and high clouds out there, which would limit
maxes, but there`s also some clearing to our west, so nothing
that gives me confidence to change anything attm.

Previously...The remnant low and associated tropical moisture
from Beryl, currently near the Great Lakes, will move today and
into New England by this evening. Despite the fact that the
close low at 500 MB is slowly filling during this time, there is
a wave oncoming out of the base of the trough into the ridge
ahead of it. Theres also a sort of double whammy when it comes
to jet dynamics that move across with this system, and although
they are linked as well as they could be should be enough to UVV
especially this afternoon and evening. Combine all this with
the hot and humid air mass at the surface, and this is a fine
recipe for convection this afternoon. With triple point tracking
out of central NY and into N NH during the afternoon, this adds
a threat of severe this afternoon. Best chance looks to be
across central and SW NH, but could see damaging winds into
western ME as well and across all of NH. Given the location of
the triple point and the good shear, theres an outside chance
of of a tornado across central and SW NH as well. Also, any
storms will be capable of torrential downpours given the deep
layer tropical environment that will move into the after this
afternoon. So will have to watch back-building cells and
training this afternoon into this evening as well. Highs will
not be quite as warm as Tuesday, but could it could hot in spots
depending on how quickly storms forms to our west today, and we
get convective anvil debris to move in. Still highs will range
from the low 80s in the mtns to around 90 in S NH.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
As for tonight, the main forcing at 500 MB weakens somewhat and
with the loss of heating, but will still have the tropical air
mass and a weak sfc front near the intl border, as well as that
second round of jet dynamics peaking in the second of the night.
There should be enough to produce convection thru the night,
especially as get closer to the intl border. The ECMWF and ts
ensembles has been persistent for several runs in keeping
heaviest rain in the far N, and in srn QC. Theres till
uncertainty and certainly cells that develop s of the front
could also train as well, so the concern for FF across much of
the CWA remains overnight. To the S NH and along the ME coast,
showers and storms may end up being quite limited overnight.
Otherwise itll be another balmy night with lows mostly in the
upper 60s to low 70s, but mid 60s in the far N.

By Thursday morning the tropical part of the air mass will be
exiting to the east, but the actual 500 MB trough will be
passing closest to us, but still passing to our N and W, so some
showers are possible especially in the morning, but could even
see some clearing in the S mid to late afternoon, which will
allow temps to jump back up into the id to upper 80s there, and
generally be in the 70s elsewhere, with little change to
humidity.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Persistent warmth and humidity will continue throughout the
long range portion of the forecast. Short waves crossing through
the region will allow for scattered showers and thunderstorms
most days, especially during the afternoon hours and away from
the immediate shoreline. The exception may be on Sunday when
some ridging will occur aloft over the region.

Overnight fog may be problematic, especially over the coastal
waters with such high dew points over the Gulf of Maine. Have
included patchy fog most overnight and early morning periods.

A pattern change may occur next week as a trough enters southeastern
Canada. Cooler and drier air may reach New England during that
period.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Any fog at KHIE or KRKD should improve to VFR
after sunrise and likely prevails for all TAF sites into early
afternoon. Showers and thunderstorms develop in the afternoon
and will bring the threat of flight restrictions mainly along a
line from KLEB to KCON to KPWM and points northward into
Wednesday night. Patchy fog will bring the threat for flight
restrictions across much of the area.

Long Term...Mainly VFR during the daytime hours through much of
the extended. However, there will be some scattered shower and
thunderstorm activity especially during the afternoon and
evening hours leading to brief periods of IFR conditions. LIFR
and IFR conditions may occur during the nighttime periods.

&&

.MARINE...
Short Term...Steady southerly flow will prevail over the waters
through today while gusts remain at or below 20 kts. Seas will
also stay below SCA thresholds. Storms forming over the land
will have the potential to track into the waters this evening
before diminishing after sunset. Humid air over the waters will
continue the threat for marine fog tonight through Thursday
morning at least.

Long Term...A persistent southerly flow will continue over the
coastal waters through the period. However, for the most part
this will be below SCA levels. Patchy fog may be problematic
with the high levels of moisture over the region leading to low
visibilities at times.

&&

.HYDROLOGY...
Tropical-like downpours possible today and tonight, Flood Watch
in effect. WPC has issued a rare Moderate Risk for the White
Mountains region of NH, with a slight risk for the remainder of
the CWA. Have left S ME and NH out of the watch based on dry
antecedent conditions and lesser risk of heavier rains. A warm
front lifting north this morning will put the region in the warm
sector with heat and humidity rising. Thunderstorms
are expected to develop along and ahead of this front as daytime
heating and upper lvl dynamics become more conducive. PWATs are
expected to surge to 3.5 standard deviations above normal and
potentially near record levels of 2-2.25". The tropical-like
airmass with warm cloud depths over 13k ft will support warm
rain collision-coalescence, an extremely efficient rain with
blinding rainfall rates. Any cells this afternoon will be fairly
discrete, but repeating storms could trigger flash flooding. The
main concern for flooding will be as the remnants of Beryl moves
in tonight. The focus for the heaviest rain will be along the
frontal boundary which is projected to line up over the flood
watch area across ME and NH. There could be a significant
gradient in rainfall with amounts of 5" possible along the axis.
The intensity of the rainfall will be a key driver in the flood
risk as 2" in 30 min is possible, capable of causing washouts
and rapid runoff especially in steep terrain. Riverine flooding
is not anticipated with the only exception being some fast
responding streams in the hilly terrain.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Flood Watch from 2 PM EDT this afternoon through Thursday
     morning for MEZ007>009-012>014-020>022-033.
NH...Flood Watch from 2 PM EDT this afternoon through Thursday
     morning for NHZ001>009.
MARINE...None.

&&

$$


NEAR TERM...Cempa
SHORT TERM...Cempa
LONG TERM...Cannon
HYDROLOGY...Jamison