Portland, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

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FXUS61 KGYX 141036 AAA
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
636 AM EDT Sat Jun 14 2025

.SYNOPSIS...
At least for the southern half of the forecast area this will
mark yet another Saturday with measurable precipitation. The
good news is that this rain event will be light and short lived.
By this afternoon at least partial clearing is expected for all
parts of the area. It may be too late to warm things up much,
with high temperatures only the lower 60s across southern New
Hampshire. More in the way of sunshine by Sunday will allow for
readings to climb back into the lower 70s. It will continue to
warm up with increasing humidity early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...Adjusted PoP based on latest radar and observational
trends. Otherwise no significant changes to the forecast.

Previous discussion...Two areas of precip are moving thru the
forecast area at this hour. To the north a band of light rain
has developed and is sliding east southeast from the Lake
Champlain area to the White Mtns. I think that upsloping winds
are aiding in precip formation across the Upper CT River Valley
where very light accumulations have been observed at HIE.
Farther east the opposite is occurring with downsloping leading
to dry conditions or trace rainfall amounts.

The southern area of showers is more convective in nature and
rainfall rates are slightly higher but not by much. Those
showers have probably reached their northern extent at this
hour...and will continue to slide eastward thru the morning
hours.

By mid morning all of this precip will be exiting the forecast
area to the east. Gradual clearing is anticipated from the
north...and as a result high temps will be inverted across the
region. The warmest temps near 70 will be along the Canadian
border...with low 60s expected across much of southern NH.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Drier air will continue to filter into the area from the
north...with clouds clearing from north to south. Just north of
the retreating boundary hi-res guidance suggests that moisture
pooling in easterly flow may lead to some areas of fog breaking
out along the ME coast overnight. This is pretty low confidence
because of model tendency to rush marine fog development...so
at this time I have not added it to the forecast. On Sun...a
little more sun and a little less onshore flow will lead to
warmer temps than today. It should manage to climb to around 70
for most areas.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
1045 PM Long Term Forecast Update... Little change in the latest
National Blend of Models forecast guidance. Main theme will be
for gradually warming temperatures along with typical Summer
afternoon showers/storms.

Previously...
Overview...

Temperatures start to rebound on Sunday in the wake of
Saturday`s front. A warming trend continues through the rest of
the work week. A low pressure system likely passes north of New
England on Wednesday, bringing and increased chance for
thunderstorms. A cold front approaches from the west late week,
likely arriving Thursday night to Friday night with an increased
chance of showers, followed by relatively cooler and drier
conditions.

Details...

Seasonably cool conditions are likely on Sunday with more
sunshine as high pressure passes through Atlantic Canada. The
high brings mainly dry conditions early in the week. A southerly
flow sets up late Monday as the high moves off to the east,
with temps warming progressively through mid to late week and
peaking on Thursday in the high 80s to possibly low 90s.

A weak area of low pressure likely passes north of New England
on Wednesday. This brings an increased chance for showers and
storms across the higher terrain and northern areas Wednesday
afternoon. Isolated showers and storms are possible elsewhere in
an increasingly humid airmass, but are likely to remain more
localized as the more organized forcing passes to the north
closer to the low.

Another low pressure system likely moves through the Great
Lakes mid to late week, with an associated cold front
approaching New England from the west during this timeframe.
Moisture continues to increase ahead of this front on Thursday,
with dew points likely starting to push into the 70s. With the
combination of rising temps and dew points, heat indices may
approach the mid 90s by Thursday across southern locations.
Additionally, airmass showers and storms are likely again on
Thursday, especially across the higher terrain.

The front likely passes through sometime in the late Thursday
night to Friday night timeframe. Storms are expected with the
front, but the timing of the frontal passage will be a
determining factor in how widespread or organized these storms
would be. Drier air returns behind the front by either Friday or
Saturday, with seasonable temperatures looking more likely for
early next weekend.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Short Term...SHRA will continue to lift north into southern
portions of the forecast area this morning. Despite that CIGs
are generally expected to remain VFR. Across southern NH
terminals some MVFR CIGs are possible thru the afternoon near
the stalled front. Starting mid morning drier air will begin to
filter in from the north. Any MVFR conditions will become VFR by
late afternoon. Tonight some hi-res guidance hints at fog
developing near the coast...but given the tendency for models to
rush this I have very low confidence in this outcome.

Long Term...VFR likely prevails during the daytime from Sunday
through midweek next week, with nighttime valley fog possible
each night. Marine fog is possible at RKD by midweek as the
airmass moistens. Chances for scattered afternoon showers and
storms increase across interior terminals starting Wednesday and
continue through late week. More widespread showers and storms
are possible late Thursday or Friday.

&&

.MARINE...
Short Term...Winds and seas will remain below SCA thresholds
thru Sun. Showers will traverse along a stalled frontal boundary
today and locally visibility may drop below 3 miles in the
heaviest showers.

Long Term...High pressure gradually moves eastward across the
North Atlantic through midweek next week with generally fair
conditions. A cold front approaches late in the week, with SCA
conditions possible in southwesterly flow ahead of the front by
late Wednesday.

&&

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

&&

$$

NEAR TERM...Legro
SHORT TERM...Legro
LONG TERM...Clair/Tubbs
AVIATION...Legro
MARINE...Legro