Topsham, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

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FXUS61 KGYX 090243
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1043 PM EDT Tue Jul 8 2025

.SYNOPSIS...
A weak cold front crosses the area this afternoon
and evening providing the forcing for showers and storms.
Chances for afternoon showers and storms stay in the forecast
through the Thursday. High pressure will bring a dry period
Friday into the weekend with increasing temperatures. Shower
activity and possible heat returns the beginning of next week.

&&

.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
Backdoor cold front continues to march thru NH overnight. East
of the front cooler temps but a still moist air mass will
support low clouds and some patchy fog. The most dense fog
should remain over the waters however.

The front has also undercut the instability...with convection
expected to remain elevated thru morning. Showers continue to
percolate along the gradient between the remaining elevated
instability and stable air to the north. The 09.00z GYX sounding
showed around 600 J/kg MUCAPE locally...but the OKX sounding was
over 3000 J/kg. So as long as we keep southwest winds
aloft...some advection of this instability will continue
overnight. That should be good enough to warrant PoP remaining
in the forecast overnight...but slowly diminishing to
chance/slight chance by morning. We also still have PWAT values
near 2 inches...so any convection is going to be capable of
brief torrential rain. 1 to 2 inches per hour is possible with
any shower. If a flood threat were to evolve it would be because
the heaviest showers start to train in the same location.

&&

.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Cooler conditions settle in behind the front for tomorrow, with
most spots topping out in the 70s. Some low to mid 80s are
likely reserved for the Connecticut River Valley. Behind the
front, pop up showers and mainly cloudy conditions prevail most
of the day. Scattered shower coverage increases during the
afternoon hours, especially across the higher terrain. Along
the coast, more low clouds are likely with an easterly flow.

Showers decrease in coverage Wednesday night, but some
scattered showers are likely to continue through the overnight
hours. Temperatures cool more than the last few night, with lows
dipping into the low to mid 60s in most locations.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Impacts and Key Messages:
* Summer pattern with periods of showers and thunderstorms
* No strong signals for any significant severe or flash flooding
  thunderstorms at this time.

Pattern will consist of a progressive zonal flow with two mid-level
shortwave troughs expected to cross north of the region through this
forecast period. Thursday into the evening the first organized
trough will cross the region sparking scattered showers and
thunderstorms to the region.  PWAT values could surge to 1.5" across
the area, but storm motion should be sufficient to mitigate flash
flood concerns. Effective Bulk Shear looks minimal also, so severe
threat doesn`t seem anything above marginal as worst case at this
time. Front is expect clear the area by Friday morning with some
lingering daytime instability showers possible in the mountains, but
westerly flow is expected. Ridging is expected for most of the
weekend with building heat once again, but looking dry at this point
for Saturday. The second shortwave trough will approach the area by
late Sunday, with some timing difference is the ensemble guidance.
There is a chance for thunderstorms late Sunday, but timing of this
feature is plus or minus 18hrs at this point, so will see how things
trend.  Overall looks like a descent summer weekend, albeit a little
warm. Shower activity chances and heat likely to build the beginning
the next week as temperatures trend back above normal for the heart
of summer.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Scattered showers and storms continue this
afternoon and evening. Probs remain low at most terminals, with
PWM most likely to see another shower. Ceilings lower tonight
with IFR in most locations with some fog also possible. MVFR
ceilings prevail on Wednesday, with some showers also possible
at times. IFR to MVFR ceilings prevail Tuesday with some fog
also possible.

Long Term...Fog formation is possible Wednesday night leading to LIFR
conditions as rich low level moisture remains in the area. Cloud
cover could limit this development threat. Showers and thunderstorms
expected on Thursday with clearing for Friday through Saturday with
VFR conditions expected.

&&

.MARINE...
Short Term...Conditions remain below SCA levels as a cold front
slowly moves southward across the waters tonight. Areas of fog
are likely to continue into Tuesday.

Long Term...Conditions are expected to remain below SCA conditions
through this period. Will have to watch for fog development chances
Wednesday night with NE onshore flow. Thunderstorms are possible
over the coastal water Thursday evening.

&&

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

&&

$$

NEAR TERM...Legro
SHORT TERM...Clair
LONG TERM...Dumont
AVIATION...Clair
MARINE...Clair