019
FXUS61 KGYX 140644
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
244 AM EDT Mon Jul 14 2025

.SYNOPSIS...
A cold front will near the region today with widespread showers
and thunderstorms, some of which could produce locally heavy
rainfall. Drier weather returns Tuesday, with heat and humidity
building in through late week. Chances for afternoon showers and
thunderstorms return late week.

&&

.NEAR TERM /THROUGH TODAY/...

Key Messages:

- Isolated flash flooding along with an isolated gusty
  thunderstorms is expected this afternoon through the early
  evening hours. The greatest threat is across hilly and
  mountainous areas along with locations that have recently
  received heavy rainfall.

Discussion:

Northeast radar mosaic early this Monday morning shows ongoing
convection slowly moving northeastwards extending from the
Pocono Mountains of PA up towards the Capital District of NY
state. This activity is associated with a sfc trof and is
producing instances of flash flooding. Closer to our region,
other than some spotty drizzle, conditions are mainly dry with
the stratus deck holding strong once again, resulting in areas
of fog. Current temperatures are into the 60s and little in the
way of additional cooling is expected through sunrise.

Our attention today will be towards a slow moving cold front
that will slowly cross from north to south this afternoon and
evening. Ahead of this front, a moisture rich environment will
be in place with precipitable water values up to around 2",
which is close to the daily maximum for this date. This combined
with warm cloud heights nearing 14 kft and slow MBE vector
velocity introduces the threat for isolated instances of flash
flooding. The greatest instability/moisture overlap along with
the lowest FFG lies across the western ME foothills and
mountains and extends into the Whites and towards south-central
NH. It should be noted that much of the region is experiencing
negative precipitation departures over the last few months but
some isolated locations have received recent heavy rainfall the
last few days. That being said, the latest HREF 6-hr maximum QPF
show local stripes of 2-4" of rainfall, which would likely
cause flash flooding regardless of antecedent conditions.

One of the main remaining questions is how quickly the marine
stratus can erode, as a longer residency time would reduce
instability and lower the threat of flooding with the greatest
potential for this across the coastal plain and the coast
itself. All these factors considered, the latest D1 WPC ERO has
removed the SLGT risk for the entire area with now a MRGL (level
1/4). In addition, in collaboration with neighboring offices
decided to hold off on a Flood Watch as even though localized
flash flooding remains possible, the expected areal extent does
not justify a watch. High temperatures will be into the 70s to
lower 80s.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
The cold front will gradually push through the area tonight
with convection waning through the first half of the night. The
front will washout as it reaches the coast Tuesday morning with
the airmass remaining humid over the area. This lingering
moisture will likely lead to fog developing overnight. Lows will
approach 60 degrees across the north while southern areas will
remain in the mid to upper 60s.

Tuesday will be mostly sunny and warm with highs in the upper 80s to
low 90s. After a humid morning, light SW flow will help mix out low
level moisture with dew points lowering a few degrees across the
interior. Winds turn onshore helping to cool coastal areas during
the afternoon.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Long Term Update...The latest NBM has come in slightly warmer for
Wednesday suggesting that Heat Advisory criteria may be reached
across interior western Maine and southern NH. Otherwise, no
significant changes with humidity becoming oppressive Thursday with
dewpoints into the low to mid 70s with chances of showers and
thunderstorms. A cooling and drying trend looks likely late in the
week into the weekend.

Previously...

Pattern Overview: Wednesday look mostly dry as the 500mb
pattern is zonal over the region with surface high pressure in
control. Thursday and Friday are more unsettled as a pair of
shortwaves look to cross the region. We may return to dry
weather for the weekend as global models suggest a flip back to
zonal flow aloft with surface high pressure nosing back into the
region.

Impacts and Key Messages:
* Hot and humid temperatures will make a return before becoming
  cooler towards the weekend.

Details:
Wednesday and Thursday: Wednesday looks like the hottest day in
regards to actual temperature as shortwave ridging peaks,
allowing temperatures to climb a few degrees higher. Much of the
area south of the mountains likely ends up in the low 90s, with
upper 80s to the north. Dewpoints remain similar to Tuesday,
but with the warmer surface temperatures some locations may
reach heat index values around the mid 90s. Flow turns
southwesterly Wednesday night which will begin to drive up the
dewpoints and make for a warmer night, with many locations south
of the mountains only bottoming out around 70, and upper 60s to
the north. An approaching shortwave trough may bring showers to
New Hampshire and the western Maine mountains overnight. This
will also increase cloud cover keeping surface temperatures a
few degrees cooler Thursday, but the southwesterly flow acts to
increase dewpoints further. Much of the area likely sees
dewpoints in the low 70s which will make it feel very similar to
Wednesday with heat indices approaching the mid 90s south of
the mountains. The region will be sandwiched between frontal
boundaries with a shortwave trough moving through, so heating of
this moist airmass should lead to afternoon showers and
thunderstorms. CSU machine learning is already showing low
probablilites that some stronger storms are possible, so this
will be a good period to keep an eye on. Elevated dewpoints once
again keep low temperatures around 70 south of the mountains
and in the mid to upper 60s to the north.

Friday-Sunday: Global models are in pretty good agreement that
Friday features a frontal passage which would bring relief from
the humidity and kick start a cooling trend. As usual in these
situations the front will take some time to clear resulting in
southern zones still holding on to some heat and humidity. A hot
and humid air mass plus lifting from a front usually results in
more widespread thunderstorm activity, again CSU machine
learning suggests some stronger ones, but timing will be key and
it`s too far out in time to speculate on coverage. Will stick
with the afternoon hours being the best chance for thunderstorms
to develop. Behind this front we should see much more
comfortable dewpoints and temperatures for the weekend with high
pressure taking control and keeping things mostly dry other
than chances for pop-up showers and thunderstorms in the
afternoons.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Short Term...Low ceilings and FG will continue to result in IFR
to LIFR restrictions through 12Z-14Z before improving to mainly
VFR late morning through this afternoon outside of any
SHRA/TSRA. The exception will be at KRKD where at least IFR
ceilings look to linger through the day. The greatest potential
for SHRA/TSRA will be between 15Z-02Z Tuesday with inland
TAF sites most at risk. Winds will be at 5-15 kts out of the
S-SW. Low ceilings and FG return tonight bringing additional
restrictions under light and variable flow. Mainly VFR
conditions are then expected on Tuesday with light SW flow
prevailing. No LLWS is anticipated outside of any TSRA.

Long Term...VFR likely prevails on Wednesday. Increasing
moisture Wednesday will likely lead to fog development overnight
and again overnight Thursday. Showers and thunderstorms are
also possible Thursday afternoon, but outside of these ceilings
should remain mostly VFR.

&&

.MARINE...
Short Term...Marine fog will continue to result in reduced
visibility at times through tonight with S-SW winds of 5-15 kts
and seas of 1-3 ft. Showers are possible this evening. Winds and
seas remain below SCA criteria on Tuesday with fog clearing
behind a cold front.

Long Term...Favorable boating conditions continue as the waters
remain on the periphery of the Bermuda High. Some showers and
thunderstorms may move over the waters late week with a frontal
passage. Increasing southwesterly flow midweek may also lead to
areas of fog.

&&

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

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Schroeter/Tubbs
LONG TERM...Baron/Schroeter