Hermon, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

802
FXUS61 KCAR 051834
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
234 PM EDT Fri Sep 5 2025

.SYNOPSIS...
A cold front crosses the region Saturday, stalls just offshore
Saturday night and Sunday, then moves southeast as high
pressure builds in Sunday night through Tuesday.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
Light showers will continue across the forecast area today as a
shortwave trough moves eastward. Although clouds are scattering
out across the west behind the trough, southerly flow will keep
pushing in low level moisture, and low clouds and fog will form
again tonight, with fog most likely in the marine layer south of
I-95.

On Saturday, the weather becomes more active with the
approach of a cold front. A low level jet will increase ahead of
the front, bringing increasingly gusty southerly winds through
Saturday morning. Winds may gust up to 25 mph, particularly up
the Penobscot river corridor, which will be aligned with the
main wind direction. Rain will develop from the southwest
Saturday afternoon, becoming a more dynamic system as it moves
eastward. This is where the forecast becomes most challenging
for tomorrow. CAMs are all indicating an enhanced area of
precip along the front, but where exactly that band ends up is a
little uncertain. There is high confidence that there will be a
narrow corridor of QPF amounts greater than 1 inch. Right now
that corridor seems to be located along the Central Highlands
into southeast Aroostook County, but could shift either eastward
or westward depending on the orientation of the low.

The other challenging feature with this system is the
instability and how it will manifest along this front. CAPE
values are actually somewhat low, and soundings are indicating a
pretty good cap in the low levels, in particular where the
marine layer has managed to sneak in. That being said, there is
an incredible amount of shear, around 50 to 60 and in some
places close to 70 knots of bulk shear with the strengthening
low level jet. This would definitely be conducive for putting
spin on anything that forms along the front. The question is
whether storms will be able to maximize instability to overcome
that cap and take advantage of the shear. SPC has extended the
marginal risk for severe storms to just north of Bangor, showing
a 5% risk for gusty winds. This definitely seems more likely
than any hail, with high freezing levels and a challenging
environment for mid-level growth.

Another concern is potential training with any thunderstorm
development. This seems a little more likely with high PWATs and
a storm development vector parallel with the main front. The
one fortunate thing is that FFG is very high right now with the
recent dry spell, so even with the factors aligned, we are not
likely to get enough precip in any one area to cause flash
flooding.

Thunderstorms will abate in the early evening on Saturday, but
rain will continue through the night, progressing eastward ahead
of the front. Storm total rain fall will be the heaviest in a
swath from Greenville to Houlton, around 1.25".

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
Sunday...A weak upper level shortwave rides NE along the stalled
front just offshore, potentially bringing another shot of rain
mainly in the morning and mainly Downeast. Some uncertainty as
to how far north the rain gets, and going with 60-80 percent
PoPs Downeast, decreasing to 20 percent or less in the far N/NW.
Probably another tenth to quarter inch of rain mainly Downeast.
Cooler than Saturday with highs in the 60s.

Sunday Night...Decreasing clouds and dry. Tentatively left fog
out of the forecast because there`s still somewhat of a pressure
gradient over the area and only expect minor decoupling. Lows
in the 40s to low 50s.

Monday...Upper trough axis moves through from west to east, but
upper trough is fairly flat and we are at the southern end of
the trough axis, so only expect enough instability/moisture for
isolated showers mainly in the north. A bit cooler than average
with highs in the low to mid 60s north and around 70 Downeast.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Monday night has a potential for frost, especially in the
northern 2/3 of the area, as surface high pressure settles in.
Went a bit cooler than guidance thanks to fairly high confidence
in high pressure position with good decoupling. Also put in
patchy valley fog. From Tuesday into Wednesday, high pressure
moves SE of the area with a warming trend and temperatures
returning back to around or a bit above average on Wednesday.
Probably dry through Wednesday. Next cold front looks on track
for Wednesday night or Thursday, but most models have minimal
rain with this front as it doesn`t seem to tap into much if any
moisture from the south, and going for just 10-30 PoPs. Cool air
returns behind the front for Friday.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
NEAR TERM: IFR/occasional LIFR tonight as low clouds and fog
form in the warm sector of the cold front. LLWS forming
overnight as the atmosphere decouples and the LLJ strengthens.
As the wind mixes down on Saturday, LLWS will weaken but surface
winds will increase, up to 25 kts at BHB and BGR. Clouds will
scatter out during the day, but by late afternoon on Saturday,
cigs and vis will lower to IFR/LIFR in RA. Possible TS at BGR
Saturday evening. Rain will continue overnight.

SHORT TERM:
Sunday...VFR north, and MVFR or VFR Downeast with possible light
rain and low ceilings in the morning, with any MVFR improving
to VFR by 21z as the system exits to the east. Variable wind
less than 10 kts.

Sunday night and Monday...VFR. W wind 5 kts Sunday night, increasing
to 10 kts during the day Monday.

Monday night...VFR except IFR possible in patchy valley fog late
at night. Light W wind becoming calm.

Tuesday...VFR. Light SW winds.

Wednesday...Mainly VFR, though MVFR/IFR possible near the coast
early morning. S wind around 10 kts.

&&

.MARINE...
NEAR TERM: Winds will increase to 25 kts beginning this
evening. They will taper off overnight, but return on Saturday
morning gusting as high as 30 kts. Seas will remain 3 to 5 feet
through this period.


SHORT TERM: Conditions should remain below small craft levels
Sunday to Wednesday. Seas could reach 4 ft during the day
Monday, but chance of getting to 5 feet or greater (small craft
advisory levels) is less than 20 percent.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory from 8 PM this evening to 11 PM EDT
     Saturday for ANZ050-051.

&&

$$


Near Term...LF
Short Term...Foisy
Long Term...Foisy
Aviation...LF/Foisy
Marine...LF/Foisy