Waterville, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

620
FXUS61 KGYX 300717
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
317 AM EDT Fri May 30 2025

.SYNOPSIS...
Today looks to remain mostly dry between systems with partly
cloudy skies and seasonably warm conditions. A coastal low moves
through New England on Saturday and Saturday night which will
bring a widespread soaking rain, that may be heavy at times, and
scattered thunderstorms. This will be followed by an upper
level low on Sunday. Cooler weather will linger Sunday and
Monday before a gradual warm up begins early next week as high
pressure returns.

&&

.NEAR TERM /THROUGH TODAY/...
Impacts and Key Messages:
* No significant impacts expected

Southwesterly flow along the coast has done it`s job keeping
fog confined to the coastline from Casco Bay east. Only Rockland
briefly dropped to a quarter mile with other locations staying
above a mile. Due to the isolated nature of the greatly reduced
visibilities will likely forego any products unless conditions
change drastically, but commuters along the coast should use
caution this morning. Otherwise, today will be a transition day
as we leave one system behind and await another. Most of the
area will stay dry, but there is a short wave trough draped over
the East Coast that will provide some forcing for any showers
that develop off the daytime heating. The HRRR has consistently
been showing MUCAPE values in the range of 100-150 j/kg, and
while I don`t anticipate thunderstorms, I could see these
showers containing brief downpours as moisture aloft will be
beginning to increase as well. With the area south of the
mountains seeing more sun, high temperatures there are likely
able to climb into the mid-upper 70s. North of the mountains
where there will be more in the way of clouds and showers,
temperatures likely only top out in the mid-upper 60s.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
Impacts and Key Messages:
* Strong low pressure will bring a widespread soaking rain to
  the region, with total rainfall amounts generally 1-1.5".
* No flooding is anticipated due to the quick moving nature of
  the system.


Tonight: The first part of tonight looks mostly dry with fog
once again possible at the immediate coast before a strong
coastal low pressure system makes its final approach overnight.
Rain will begin to move into southern New Hampshire after
midnight and quickly overspread the area by Saturday morning.
This initial push out ahead of the best forcing will have
lighter rates with overnight QPF totaling around 0.25-0.5" with
the higher totals being in southern New Hampshire where the rain
starts the earliest. Temperatures won`t get much of a chance to
cool before the clouds and rain move in and likely only bottom
out in the 50s.

Saturday: Widespread rain will be ongoing Saturday morning. As
mentioned we initially start with a light stratiform rain, but
as the morning goes forcing will be increasing as the system
occludes and the upper level trough becomes negatively tilted.
There is still some subtle uncertainty in the exact track of the
center of the low and this will have some bearing on where the
heaviest rates develop. It looks like the western half of New
Hampshire may stay mainly on the western side of the system
where cooler stratiform processes would prevail. Much of the
eastern part of the state and western Maine look like they will
end up in the warm sector of the system where more convective
processes would lead to heavier rates. The latest runs of the
HRRR are suggesting some halfway decent instability building in
as the system enters the region. We will also be getting
additional forcing for ascent as a 120+ kt upper level jet
streak develops offshore, putting us in the left exit region.
All this to say that the morning and early afternoon is likely
when we will see the heaviest rain rates along with a chance for
some scattered thunderstorms.

As mentioned in the previous long term discussion, this system
is quite strong for this time of year with models continuing to
forecast central pressure in the mid-980s, but there are a few
things working in our favor to keep this from becoming a higher
impact event. The first being the quick nature of the system.
This thing is in overnight Friday and mostly out by Saturday
evening, so even with some heavier rates developing in the
afternoon we aren`t all that concerned about flooding. The
second is the track, which may keep heavier rates more isolated
to begin with, if the center is more east of the CWA as
suggested by some models. When all is said and done QPF amounts
look to total around 1-1.5" with locally higher amounts in and
around the terrain as orographic lift will act as yet another
forcing mechanism to increase rates. This seems like a
reasonable range considering the ECMWF and GFS ensembles have
high probabilities of greater than 1 inch across the area, but
virtually no probabilities for 2 inches or greater. This also
agrees with the latest HREF mean values, with max values closer
to 2 inches.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
1110 PM Update...No significant changes in the latest NBM for
the long term. A secondary wave rotating over the area will
maintain chances for showers Sunday with a warming and drying
following into the middle of next week.

Previously...

Upper trof will linger Sun into Mon so the threat of diurnal
clouds and showers will remain in the forecast. Thru most of
next week ridging looks to dominate the East Coast. Warm
southwest winds and little in the way of precip is expected.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Short Term...Any low ceilings and fog from overnight will mix
out this morning with VFR becoming the prevailing condition for
today. Ceilings will thicken and lower this evening with some
fog possible again at coastal terminals before rain begins to
move into the area. Overnight through much of Saturday will be a
mix of MVFR and IFR ceilings as rain, heavy at times, moves
through the area. Scattered thunderstorms are also possible
Saturday afternoon. Northwesterly wind gusts begin to pick up
Saturday evening in the wake of the system.

Long Term...As winds turn northwesterly Sat
night and Sun...low CIGs will scatter out and lift. Some
lingering MVFR is possible Sun and Mon with CIGs and locally in
any SHRA. VFR will be widespread next week.

&&

.MARINE...
Short Term...Wind gusts and seas are expected to remain below
SCA thresholds through the day Saturday. Increasing moisture
will sustain areas of dense fog through today and then low
pressure tracking through the the Gulf of Maine Saturday will
bring rain, which may be heavy at times, and scattered
thunderstorms to the waters.

Long Term...With winds largely remaining southwesterly over the
waters only marginal SCA gusts are anticipated. However the
consistent wind direction may be enough to build seas over 5 ft
outside of the bays into Sun morning. Winds and seas will
diminish Sun afternoon and remain below thresholds next week.

&&

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

&&

$$

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