Lewiston, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

957
FXUS61 KGYX 280757
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
357 AM EDT Sat Jun 28 2025

.SYNOPSIS...
Low pressure crosses the area tonight. 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.
Outside of some mountain showers, the middle to second half of
next week looks mostly dry and seasonably warm.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Rounds of showers and a few thunderstorms continue to move
across the north this morning, with scattered shower activity
elsewhere. Despite temperatures in the upper 40s to low 50s,
thunderstorms are developing as elevated instability continues
to increase with WAA aloft.

Periods of rain and convective showers continue across the
north through most of the afternoon, while conditions elsewhere
generally see decreasing shower activity through the day. A
surface warm front is likely to make some progress into New
Hampshire during the afternoon hours, bringing highs into at
least the mid 70s across southern New Hampshire and through the
Connecticut River Valley. Additionally, a few stronger
thunderstorms are possible across southwest New Hampshire late
this afternoon as the warm front serves as a focus point for
convection. North of the warm front, mainly cloudy, cool, and at
times foggy conditions are expected much of the day with highs
in the 50s to mid 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Low pressure tracks through Quebec tonight, with a decreasing
shower trend through the overnight hours, and some clearing
late. Low temperatures only fall by a few degrees north of the
warm front tonight with lows ranging from the mid 50s to low
60s, and lows in the mid 60s south of the front. The cold front
associated with the low moves through late tonight and early
Sunday morning, bringing drier and warmer conditions.

Westerly winds on Sunday help to usher in a warmer airmass,
while a downsloping wind direction warms temps further. Highs
range from around 70 across the north, to the low to mid 80s
downwind of the mountains to the coast. Through the higher
terrain, the upslope wind direction generates more clouds and
some isolated showers through the daytime, while mainly sunny
conditions are expected downwind of the mountains.


&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
High pressure slides across New England Sunday afternoon into
Monday. High pressure moves well offshore Monday night as an
area of low pressure tracks northeastward through Quebec. Deep
moisture will advect into New England Tuesday ahead of a cold
front that will likely bring thunderstorms through Tuesday
afternoon and evening. Cyclonic flow aloft will keep low chances
for showers and afternoon thunderstorms in the forecast through
mid week followed by high pressure building in late next week.
Monday and Tuesday will be the warmest and most humid days of
the period with the middle to later half of next week remaining
seasonably warm with highs in the 80s.

Deep layer ridging builds over the Northeast Monday allowing
for mostly sunny skies and warmer temperatures as highs climb
well into the 80s with interior locations getting into the low
90s. Dew points will be in the low to mid 60s and won`t lead to
much of a difference in heat indices versus the ambient air
temperature.

Global models remain in decent agreement in a trough swinging
across the Great Lakes Monday night with an area of low pressure
tracking through Quebec Tuesday. Deep moisture will move into
the forecast area with dew points climbing to near 70 degrees
and PWATs approaching 2 inches. Model consensus also continues
to favor a cold front crossing the area during the second half
of the day that would allow for sufficient instability for
thunderstorms. The latest LREF shows MUCAPE around 1500 J/kg
with around 30 kts of deep layer shear. This continues to
suggest conditions may become favorable for strong to severe
storms, although the finer details will remain unresolved until
we enter the window of CAM guidance.

The cold front will push offshore Wednesday morning while
cyclonic flow aloft will remain through Thursday. Embedded waves
moving through the cyclonic flow will bring low chances for
showers and perhaps thunderstorms across the north Wednesday and
Thursday afternoons. High pressure then looks to build in late
in the week.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Ceilings lower to MVFR and then IFR through the
morning to early afternoon. Scattered showers continue through
the day, with low PROBs for a thunderstorm at HIE this
afternoon. Conditions gradually improve to MVFR and then IFR
from southwest to northeast tonight as a cold front moves
through. VFR then prevail on Sunday.

Long Term...Mainly VFR through Monday, while increasing
moisture will bring the potential for night time fog Sunday
night. A cold front brings chances for thunderstorms Tuesday
that will bring the potential for brief restrictions.
Improvement is likely into Wednesday.

&&

.MARINE...
Short Term...Low pressure passes north of the waters tonight. A
cold front crosses through early Sunday morning, with high
pressure building in from the west through the day on Sunday.
Some seas around 5ft are possible across the far eastern waters
late tonight and Sunday morning.

Long Term...Offshore flow will likely turn out of the south by
Monday as high pressure slides over the waters. South to
southwest flow increases Monday night into Tuesday ahead of a
cold front with SCAs likely needed over the outer waters
Tuesday. A cold front will cross the waters late Tuesday
bringing chances for thunderstorms.

&&

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

&&

$$


NEAR TERM...Clair
SHORT TERM...Clair
LONG TERM...Schroeter