South Portland, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

738
FXUS61 KGYX 030810
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
410 AM EDT Thu Apr 3 2025

.SYNOPSIS...
A warm front is lifting through northern New England this
morning. While much of the area will be rain, a period of snow
changing to a wintry mix is expected across interior western
Maine and parts of the White Mountains. Fair weather returns for
Friday as a high pressure builds into the region. Yet another
chance of a wintry mix arrives this weekend as a storm heads
through the St. Lawrence River Valley. The pattern will remain
unsettled into early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
No major changes to the forecast with this update. Temps are
fairly consistent across the forecast area...but moisture is a
little more variable from southwest to northeast. From a HIE to
RKD line and points north...low level RH values remain around
60 percent. That leaves some room for wetbulb cooling down
below freezing. These areas will be most likely to see a period
of snow then wintry mix this morning. I have left winter weather
advisories in place...but may be able to start trimming these if
temps do not budge from current readings.

The second round of precip is now pushing into the local area at
this hour. While the band of precip is relatively narrow...it is
quite focused along the mid level warm front. Within the warm
sector lapse rates are quite steep...and there is quite a bit of
convection along both the warm and cold fronts. I have added
isolated thunder to the forecast area southern NH...where the
warm front will linger the longest.

I have opted for the cooler of guidance today...as cold air dams
are often more stubborn than modeling would have you believe.
Moist advection thru the day may also leads to blossoming areas
of fog later today and into the evening. I have added this to
the forecast starting mid afternoon as well.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Cold front will cross the region tonight and low level moisture
will be swept eastward with it. Clouds will scatter out south of
the mtns...while some upslope cloud cover lingers in the mtns
and perhaps a few showers. Temps should be a steady step down
in CAA...so I leaned away from MOS guidance. Fri will be warmer
and breezy for an otherwise decent spring day.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
04Z Long Term Update... Latest guidance continues to be in good
agreement for a period of precipitation from a wave of low
pressure to impact the area Saturday afternoon through part of
Sunday. Temperature profiles look to support a period of mixed
wintry precipitation initially across the foothills and points
north with primarily rain likely further to the south and east.
Did continue to incorporate this mixed precipitation in the
weather grids. After this system mainly dry and cool
temperatures look to prevail.

Previously...
Overview: High pressure will build in Friday for
fair weather. A period of active weather follows as wave of low
pressure track along a frontal zone that slowly shifts south of
the area early next week. The first wave will bring widespread
wintry precipitation late Saturday into Sunday. Thermal profiles
with this system will support snow/wintry mix across the
interior early Saturday night with a transition to rain from SW
to NE Sunday morning. There may be a lull in precipitation
Sunday afternoon before the next wave of low pressure tracks
across southern New England Sunday night. Chances for
precipitation drop off Monday while global models suggest
additional systems will be possible towards the middle of next
week with a trough approaching the Northeast.

Impacts: Snow to a wintry mix could bring slick travel across
northern areas late Saturday through Saturday night.

Details: Drier air will work into the area Thursday night into
Friday on NW flow. A NW gradient will remain over area Friday as
high pressure builds in from west with wind gusts approaching 25
mph. Skies will turn mostly sunny by Friday afternoon with highs
ranging from the mid 40s north to mid 60s across southern NH. High
pressure will crest over the area Friday night allowing for lows to
drop into the low 20s to low 30s from north to south.

A wave of low pressure will track from the Ohio Valley towards the
St Lawrence Valley late Saturday into Sunday with precipitation
likely overspreading the area by Saturday afternoon. A dry airmass
in place will allow for some wet bulbing leading precipitation
starting as snow across the north and a mix of rain and snow
south of the mountains. Warm air advection will continue through
Saturday night with precipitation changing to a wintry mix
across the north and rain across the south by Sunday morning.
Temperatures will eventually rise above freezing across all
areas after day break Sunday with rain becoming the dominant
precipitation type. Precipitation will taper off Sunday
afternoon before the next wave of low pressure approaches Sunday
night.

The next wave of low pressure will bring chances for rain south
of the mountains and a mix of rain and snow across the north
Sunday night into Monday. Colder air attempts to work into the
region Monday night that may allow for snow showers south of the
mountains.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Short Term...Widespread MVFR CIGs will continue to gradually
lower thru sunrise. Precip is also moving into the area again
from the southwest. Temps continue to creep upwards and so
largely rain is expected at TAF sites in NH. Also cannot rule
out a rumble of thunder across southern NH terminals. HIE may
have a brief period of snow or a wintry mix before changing to
rain. Across ME AUG and RKD may start as snow before mixing and
eventually changing to rain this morning as well. Widespread IFR
or lower conditions are expected thru today and into the
overnight when a cold front will then mix out the cloud cover
and VFR conditions return to the area.

Long Term...Lingering MVFR cigs Thursday night will transition
to VFR Friday into Saturday morning. Waves of low pressure
brings a brief period of a wintry mix late Saturday changing to
rain Saturday night with rain continuing through Sunday. Periods
of IFR to LIFR will be possible late Saturday through Sunday.
Some improvement is possible Sunday afternoon before the next
system crosses New England Sunday night into Monday.

&&

.MARINE...
Short Term...South southwesterly LLJ will move across the waters
this morning with gusty winds and building seas. SCA remains in
effect for all waters. Areas of fog are possible tonight before
the cold front crosses the waters. It will remain breezy behind
the front thru Fri which will delay seas diminishing below 5 ft
outside of the bays until Fri afternoon.

Long Term...Winds shift out of the west Thursday night with gusts to 25
kts until Friday morning. High pressure builds over the waters
Friday with winds and seas likely dropping below SCA thresholds by
Friday afternoon. Waves of low pressure will track across New
England this weekend with winds and seas approaching SCA thresholds
Saturday night into Sunday. Winds will drop below 25 kts Sunday
night while seas remain elevated into Monday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until noon EDT today for MEZ007>009-
     012>014.
     Winter Weather Advisory until 10 AM EDT this morning for
     MEZ018>022-033.
NH...Winter Weather Advisory until noon EDT today for NHZ001-002-
     004.
     Winter Weather Advisory until 10 AM EDT this morning for
     NHZ003-005>011-015.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     ANZ150>152-154.
     Small Craft Advisory until noon EDT today for ANZ153.

&&

$$

NEAR TERM...Legro
SHORT TERM...Palmer
LONG TERM...Schroeter/Tubbs
AVIATION...Legro
MARINE...Legro