336
FXUS61 KGYX 080611
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
211 AM EDT Tue Jul 8 2025

.SYNOPSIS...
The heat winds down today, with hot temperatures mainly
confined to York county and the Seacoast. A front finishes
crossing the area this afternoon and evening providing the
forcing for showers and storms. Showers and storms today are
capable of producing heavy rain, and pose a localized flash
flood risk for locations that see repeated rounds of them.
Chances for afternoon showers and storms stay in the forecast
through the rest of the week. Temperatures will be cooler for
the second half of the week.

&&

.NEAR TERM /THROUGH TODAY/...
Impacts and Key Messages:
* Heat indices will reach the mid 90s again in southeastern New
  Hampshire.
* Localized flash flooding is possible along the coastal plain
  tomorrow afternoon as tropical moisture will aid in the
  development of heavy rain. Isolated amounts greater than 2"
  are possible in areas that see repeated rounds of heavy
  showers/storms.

Heat: The frontal boundary remains hung up north of the mountains
which will allow for one more day of hot and humid conditions in
southeastern New Hampshire where high temperatures are likely to
climb into the low 90s. With dewpoints still around 70F south
of the front, this will feel more like the upper 90s. The Heat
Advisory remains in effect with no changes. Locations outside of
the heat advisory, should start to feel the effects of the
frontal passage as drier and cooler air fills in behind the
front,or the cooling effects of thunderstorms. This will make
for a stark temperature contrast across the area, with locations
north of the mountains in the 70s and locations to the south in
the low to mid 80s. The southern Maine Coast likely will see
temperatures in the upper 80s to near 90, which may approach
heat indices in the mid 90s, but this is also the area where
confidence is higher for heavy rain and thunderstorms so it
might not last as long and therefore I do not plan to expand the
Heat Advisory.

Thunderstorms: Modest CAPE approaching 1000 J/kg will develop
as a result of daytime heating and be supportive for
thunderstorms this afternoon as the frontal boundary slowly
sinks southward, but weak shear (only around 20 kts) and lapse
rates (only around 5.5-6 C/km) should keep them loosely
organized and sub severe.

Heavy Rain: This is the most concerning threat for this
afternoon as tropical moisture from the remnants of former TC
Chantal become entrained along the frontal boundary, driving
PWATs up near 2" over the coastal plain. Forecast soundings show
potential for very efficient warm rain processes as warm cloud
depths exceed 12kft. Forecast soundings are also supportive of
back building and training storms with Corfidi vectors around 5
kts, and with mid level flow only around 20kts or less, these
storms won`t be the quickest movers. Current 1 hr Flash Flood
Guidance is still on the high end on the coastal plain (around
2.5-3"/hr) so any one storm isn`t as likely to cause issues.
However, 3 hr flash guidance is only a bit higher (3-3.5") and I
feel like this could be achieved fairly easily at any location
that experiences training of storms. Hi-res guidance has been
suggesting isolated bullseyes of 3"+, mainly targeting the Maine
coast, but there is plenty of uncertainty in where exactly
training might set up. With the uncertainty in exact location
and what looks like a more isolated flash flooding threat, don`t
see a need for a widespread Flash Flood Watch. We can handle
areas of concern with short fuse warnings. WPC does have much of
the I-95 corridor up to Portland, in a Slight Risk ERO.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
Impacts and Key Messages:
* No significant weather impacts expected

Tonight: The front looks to finally clear the coast tonight
which will bring heavy showers to an end, with some lingering
light showers possible through the night as the region gets more
under a broad troughing pattern. The actual remnants of former
TC Chantal will make a close pass in the early hours of
Wednesday morning which may bring some additional showers into
southern New Hampshire, but there is uncertainty between models
on just how far north these will come. Otherwise, low
temperatures look to drop into the low to mid 60s which should
feel much more pleasant compared to the last few nights.

Wednesday: Broad troughing over the region will support a
chance for scattered showers during the day Wednesday and maybe
some rumbles of thunder as latest CAMs suggest a couple hundred
joules of CAPE may develop. Otherwise it looks like a pleasant
summer day with high temperatures in the mid to upper 70s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Evening Update...No significant changes to the long term period
with the inclusion of the latest NBM. Chances of showers and
afternoon thunderstorms remain in the forecast late week as a
trough swings through. Global models are beginning to hint at
the potential for a drier weekend with deep layer ridging
potentially building in. The beginning of next week looks
unsettled as another trough approaches the region.

Previous Discussion...
The second half of the week and next weekend will feature
cooler temperatures and unsettled weather. High temperatures
look to be in the 70s Thursday and Friday as ensemble guidance
suggests a weak mid-level trough moves in from the west. Some
weak forcing and daytime destabilization may allow for some
diurnally driven showers and thunderstorms to form on Thursday
and Friday afternoons. Thunderstorm chances look to be the
highest on Thursday, especially in the CT River Valley and
locations north of the mountains.

The 500mb trough will slowly loosen over the weekend, with some
warmer high temperatures on tap to start next week. Saturday
and Sunday, highs look to be near 80F most places, with lower
80s early next week. Next weekend looks mostly dry, though a
shower or two can`t be ruled out. More unsettled weather is
possible to start off next week.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Short Term...Showers and thunderstorms are possible at all
terminals this afternoon, but confidence is highest at AUG, PWM,
and RKD so that is where they are included in the TAFs at this
time. Once showers and storms clear the area Tuesday night, fog
is likely to develop, especially in areas that saw rain during
the day. After any fog burns off Wednesday morning, the
remainder of Wednesday should see VFR prevail with just some
scattered showers and an isolated storm, during the afternoon
that may cause a brief restriction.


Long Term...Generally VFR is expected through most of the extended,
though scattered showers and thunderstorms in the second half of the
week could allow for some brief restrictions.

&&

.MARINE...
Short Term...Wind gusts and seas remain below SCA criteria
through Wednesday. Winds will shift onshore with the passage of
a front tonight.

Long Term...2-4ft seas are expected through the second half of the week,
with easterly winds at 5-12kts expected. No SCA issuance
expected for the time period.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for NHZ010-012>014.
MARINE...None.

&&

$$

NEAR TERM...Baron/Legro
SHORT TERM...Baron/Legro
LONG TERM...Baron/Palmer