Topsham, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

057
FXUS61 KGYX 281921
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
321 PM EDT Sat Jun 28 2025

.SYNOPSIS...
Low pressure crosses the area tonight with thunderstorms
possible through the evening. High pressure builds in Sunday
and Monday for mostly dry conditions and a warming trend. Low
pressure tracking through Quebec will drag a cold front across
the area Tuesday bringing chances for thunderstorms, a few of
which may be on the stronger side. Outside of some mountain
showers, the middle to second half of next week looks mostly dry
and seasonably warm.

&&

.NEAR TERM /THROUGH TONIGHT/...
A warm front is lifting towards the area this afternoon with an
area showers and embedded thunder pushing northeast through
central Maine. Cloud cover is starting to thin across western
New England with areas of convection developing along a cold
front across Upstate NY and central PA. Low clouds and patchy
fog will likely persist across much of Maine through sunset
while some surface heating near the CT Valley and SW NH will
allow MU CAPE to rise to around 1000 J/kg. CAMs generally agree
that the convection to the west of New England will weaken as it
approaches the CT Valley between 00Z and 02Z this evening when
instability will be waning. Isolated to scattered thunderstorms
remain in forecast through this evening and a strong storm or
two cannot be ruled out across western NH.

Chances for showers and thunder will diminish after 02Z tonight
with areas of fog likely along the coastal plain and within
interior valleys. Some fog may become dense near the coast
before winds shift out of the NW towards daybreak. Lows tonight
will range from the mid 50s north to mid 60s south.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
A cold front will be pushing offshore Sunday morning with high
pressure building in through Sunday night. Sunday will be a nice
day with a mix of clouds and sun and highs ranging from the 70s
north to 80s south.

High pressure cresting over the area Sunday night will likely
lead to fog developing within area valleys. Otherwise quiet
weather is expected with lows ranging from the mid 50s to low
60s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Pattern Overview: Our weather pattern looks to remain on the
unsettled side as we end up in broad troughing for much of next
week at the 500 mb level with a series of surface fronts as
well. Global models are hinting at a sharper trough toward the
July 4th holiday, but also a bit of a drier airmass that could
limit shower activity.


Impacts and Key Messages:
* Tuesday is a day to watch as warm moist conditions ahead of a
  cold frontal passage may lead to the development of some
  stronger thunderstorms and heavy rain.


Details: Monday: Monday looks to be warm and dry as a 500 mb
ridge builds over the northeast. 850 mb temperatures will build
to +16-18C under this ridge which, with clear skies and good
mixing, would support surface temperatures in the mid to upper
80s across most of the area, and near 90 in southern New
Hampshire. Northwesterly flow should keep dewpoints in the
comfortable range making for a pleasant summer day rather than
the oppressive heat we saw earlier this week. Skies look to
remain clear for a good portion of the night, but 850 mb
temperatures continue to build so temperatures Monday night
likely only fall into the 60s before leveling off as clouds
thicken toward sunrise.

Tuesday and Wednesday: As the ridge shifts off to the east,
flow becomes southwesterly which looks to drive dewpoints up in
to the upper 60s to near 70. This would have some locations
feeling sticky with actual temperatures in the mid to upper 80s
south of the mountains, feeling more like low to mid 90s.
Southeastern New Hampshire may even approach Heat Advisory
criteria if trends hold. Other than a little bit more of an
uncomfortable day, this heat and humidity may provide forcing
for some stronger thunderstorms later on Tuesday as a cold front
approaches the area. The latest Long Range Ensemble Forecast
has stayed pretty consistent with 1500-2000 J/kg of MUCAPE and
30-35 kts of deep layer shear, suggesting some organized
convection as forcing for ascent increases ahead of the front.
Current PWATs are modeled to be around 2", so these storms may
contain heavy rain at the very least. Any finer details will
have to be resolved by CAM guidance later down the road, but
this certainly remains a period to watch. Skies clear behind the
front, but 850 mb temperatures remain warm so Tuesday night
looks like another night in the 60s for low temperatures.
Wednesday looks like a drier day for the majority of the area
with a more westerly flow maybe supporting showers in the
mountains, similarly another front looks to approach in the
afternoon bringing about a chance for a rumble of thunder as
well.

Thursday-Saturday: Models are in surprisingly good agreement
that a sharper trough looks to approach the region late week.
Where they differ is time of departure, with the GFS being the
quickest and the Euro and Canadian keeping in under the
influence of the trough through Saturday. Another thing of note
is that the airmass around this time looks fairly dry so don`t
assume your holiday weekend is going to be a wash. There is
still a lot of time for things to change, but my forecast
remains on the optimistic side (and close to NBM consensus) with
just isolated to scattered showers at this time.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Short Term...Low cigs and reduced visibility in showers and fog
will bring IFR/LIFR conditions across much of the area tonight.
A cold front will bring chances for TSRA near the CT Valley
around 00Z with the threat for thunder diminishing after 02Z.
Conditions likely improve to VFR Sunday morning. Valley fog will
likely bring restriction to KLEB and KHIE Sunday night and
possibly to KCON and KMHT.

Long Term...VFR prevails most days through Thursday, with the
exception being on Tuesday when a cold front brings with it a
chance for thunderstorms and heavy rain, and therefore brief
restrictions. Some fog development is possible Monday night as
moisture increases, and again Tuesday night at terminals that
see rain.

&&

.MARINE...
Short Term...Winds and seas will remain below SCA thresholds
tonight through Sunday night. A warm front lifting into the
waters will maintain areas of fog that could become dense
tonight.

Long Term...SCA conditions are not expected Monday as high
pressure slides over the waters. A cold front looks to cross the
waters Tuesday night, which may bring about brief SCA
conditions and chance for thunderstorms in the afternoon and
evening. Sub SCA criteria then returns through Thursday. Flow
will remain generally southwesterly.

&&

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

&&

$$

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