379
FXUS61 KGYX 061020
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
620 AM EDT Sun Jul 6 2025

.SYNOPSIS...
Heat and humidity continue to build today with shower and
thunderstorm chances mainly confined to the mountains. Showers
and thunderstorms are possible again Monday and Tuesday as a
cold front slowly moves through the region. The front then
stalls near New England for much of the week, keeping the chance
for showers and storms each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
620 AM Update...Quick update just to bring things in line with
observations. The forecast remains in good shape with a warm and
breezy day expected.

Previous Discussion...

Impacts and Key Messages:
* Heat indices will reach the mid to upper 90s south of the
  mountains
* A few strong thunderstorms capable of producing gusty winds
  are possible in the western Maine mountains and Kennebec
  Valley this afternoon and evening.

At the time of this writing a few leftover showers from the
decaying MCS are approaching north central Somerset county so
have low chance PoPs there for the next couple of hours.
Otherwise, 500 mb heights continue to build overhead today with
850 mb temperatures climbing to around 19C. Partly to mostly
sunny skies south of the mountains will aid in efficient mixing
and amount to surface temperatures in the low to mid 90s. This,
combined with southwesterly flow driving dewpoints up into the
upper 60s to near 70, is going to amount to temperatures feeling
more like the mid to upper 90s. No changes to the Heat Advisory
are necessary as these remain the areas with highest confidence
of reaching criteria. The Midcoast will likely stay a bit
cooler due to an onshore breeze, and the mountains will see more
in the way of cloud cover during peak heating hours, so
temperatures in these locations end up more in the 80s to near
90. With the heat and the moist airmass, there remains a
conditional threat for a few strong storms Sunday afternoon and
evening. Modest CAPE and shear look to build ahead of an
advancing cold front, but the cold front won`t make it very far,
stalling north of the International Boarder. This means the
best forcing and likely point of convective initiation will be
in the western Maine mountains. The storms may be able to hold
themselves together into the Kennebec Valley, but likely not
much further as they would begin to run into the more stable air
near the coast. Mid level lapse rates are only around 5 C/km,
which may also help to limit coverage, but latest forecast
soundings have well defined inverted Vs so gusty winds are
certainly the main threat with any stronger storms.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
Impacts and Key Messages:
* Warm overnight temperatures in the upper 60s and low 70s will
  add to heat stress accumulated today, providing little relief
  before another day with heat indices around 95F on Monday.
* A few strong to severe thunderstorms capable of producing gusty
  winds, hail, and downpours are possible Monday afternoon and
  evening.

Sunday Night: Thunderstorms die off quickly as they lose the
heat of the day, but the frontal boundary remains a forcing for
showers to ride along overnight, so chance PoPs persist in the
mountains. Dewpoints remain elevated overnight so apparent
temperatures stay in the upper 60s to low 70s which won`t
provide much relief and add on to heat stress accumulated
earlier in the day. For this reason the Heat Advisory will run
right through the night.

Monday: The ridge will begin to shift eastward Monday with
height falls occurring over the region. Waves of low pressure
will continue to ride along the frontal boundary which begins to
sink slowly southward. 850 mb temperatures come down slightly,
but the situation remains similar to what we will see today with
temperatures still climbing into the low 90s and heat indices
in the mid to upper 90s. Outside of southern New Hampshire this
is definitely more marginal, but with little relief the night
before, running the Heat Advisories through Monday still seems
reasonable when factoring in the accumulated heat stress. Monday
also looks like a better day for a few strong to severe storms
as the front sags further south into the area with similar CAPE
and shear to the day before. I keep the highest PoPs in the
mountains and foothills, but showers and storms are possible all
the way to the coast. Tropical moisture will be streaming into
the region as the remnants of Chantal move up the coast so any
storms and showers that develop will be capable of producing
heavy rain. Mid level flow around 30-40 kts should keep things
moving along nicely, but isolated flooding of poor drainage
areas is possible. Overall, ensembles keep the axis of highest
QPF to our north with probability match mean values north of the
foot hills in the 0.25-0.50 range with locally higher amounts
in thunderstorms and in central Somerset county, which is closer
to the higher QPF axis.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Evening Update...Little change in the latest National Blend of
Models (NBM) forecast guidance. Hot and humid conditions will
prevail on Monday along with scattered afternoon showers and
thunderstorms. Some of these storms could be strong to severe
with damaging winds and hail the primary hazard. The north and
mountains currently look to have the greatest risk due to the
closer proximity to an approaching cold front. The remainder of
the weak with feature cooler temperatures along with scattered
showers and storms at times, especially during the afternoon
hours with diurnal heating.

Previous Discussion...

Overview...

Relatively cooler air brings highs back into the 80s for
Tuesday and Wednesday, with scattered showers and thunderstorms
each day. The pattern then trends toward cooler and more
unsettled conditions by late in the week into next weekend.

Details...

Tuesday and Wednesday see the continued chance for scattered
showers and storms each day as the front lingers across New
England with temperatures warming into the upper 70s and 80s
each day.

By late in the week, a wave of low pressure likely rides along
the stalled front, bringing a better chance for more widespread
showers and storms late in the week. Additionally, moisture from
the remnants of Chantal may become drawn into this system,
increasing the rainfall potential. We`ll have to monitor the
progress of Chantal`s path and moisture plume through the week.

&&

.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
Short Term...Conditions remain VFR through Monday with the only
exception being brief restrictions in showers/thunderstorms
this afternoon and evening as well as Monday afternoon and
evening. These will be limited in coverage and are not included
in the TAFs at this time as confidence in any one terminal being
impacted is low. Southwesterly wind gusts 15-20kts are expected
tomorrow afternoon.

Long Term...VFR prevails most of the time at all terminals from
Monday night through Wednesday, but brief restrictions with
afternoon showers and thunderstorms will be possible at all
terminals. Chances for more restrictions increase late in the
week and into next weekend with more showers and storms
developing.

&&

.MARINE...
Short Term...Southwesterly winds increase today with gusts
around 25 kts. Seas will also build to around 5ft. While a
marginal case, an SCA has been issued with an expected increase
in recreational boating due to the holiday weekend. These
conditions diminish tonight with SCA conditions not expected on
Monday.

Long Term...High pressure remains centered off the East Coast
early this week. A slow moving cold front sags southward Monday
night and Tuesday, stalling across the waters for much of the
week. Conditions look to remain below SCA levels as the front
stalls overhead most of the week

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Heat Advisory from 11 AM this morning to 8 PM EDT Monday for
     MEZ012-018>020-023-024-033.
     Beach Hazards Statement through this evening for MEZ027-028.
NH...Heat Advisory from 11 AM this morning to 8 PM EDT Monday for
     NHZ006>015.
MARINE...Small Craft Advisory from 2 PM this afternoon to 6 AM EDT
     Monday for ANZ150-152-154.

&&

$$

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