Hermon, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

504
FXUS61 KCAR 221827
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
127 PM EST Mon Dec 22 2025

.SYNOPSIS...
High pressure will ridge across the area tonight into Tuesday.
Low pressure will slide south of the region Tuesday night into
Wednesday. High pressure will return Wednesday night. Weak low
pressure will pass northeast of the area on Thursday. High
pressure will then build over the area through Saturday.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
Key Message:
Snow is expected Tuesday night into Wednesday for all but far northeastern
Maine. The greatest accumulation will be from Coastal Hancock
County through southern Piscataquis County southwestward towards
central and southern Maine.

Discussion:
Tonight through Tuesday:
High pressure will build over the area tonight, leading to decreasing
winds and cold temperatures. Lowered temperatures across
northwestern areas compared to the NBM due to more optimal
radiational cooling conditions. Lows are expected to be around 0
to 10 below across the north and 0 to 10 above across the
southern half of the area. Clear skies early will give way to
increasing clouds in the afternoon on Tuesday with high
temperatures slightly below average, ranging from the mid teens
across the north to upper 20s along the coast.

Tuesday Night:
A shortwave trough moving into southern New England will lead to
the development of an inverted surface trough along the Maine
coast Tuesday evening through Wednesday. Significant uncertainty
remains in its exact placement, with solutions ranging from the
GFS placement near Portland to the NAM placement just east of
Mount Desert Island. Given that inverted troughs are highly
mesoscale types of events, small shifts will significantly
change snow amounts. A blended placement of the inverted trough
near the Midcoast of Maine, similar to the ECMWF and RGEM, was
favored, and also aligns with studies of where inverted troughs
are climatologically most favored to be oriented along the Maine
coast. The gradient of snowfall in the Penobscot Bay area could
be significant, with potential for warning level snowfall
prompting a Winter Storm Watch for Coastal Hancock County.
Forecast soundings show more favorable lift within the dendritic
growth zone further inland, so snow to liquid ratios may reach
or exceed 20 to 1 over or northwest of Bangor into central and
southern Piscataquis County. Winter Weather Advisories have been
issued for these areas. Further east, QPF was lowered compared
to the NBM due to uncertainty in the inverted trough positioning
and potentially a sharper gradient in QPF than the NBM is
forecasting. Far northeastern portions of the forecast area may
see little to no accumulation.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
The storm discussed above tapers off Wednesday. A weak system
moves through from NW to SE Wednesday night and Thursday, with
the potential for light snow accumulation as much as an inch or
two, but also potentially just a dusting or less. Only have a
chance of snow in the forecast for now.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Key Message 1...Potential Significant Winter Storm Late Sunday/Monday
Key Message 2...Bitter Cold Thursday Night to Saturday


Key Message 1...
The main concern in the extended is the potential for a significant
winter storm late Sunday/Monday. There is unusually good model
agreement this far out for a system of at least decent strength
around this time. Most models/ensembles have a vigorous upper
trough moving through and rapidly strengthening a surface low
pressure that moves east through the region. Models generally
favor snow, but rain/snow or rain is possible especially
Downeast if some of the warmer solutions pan out. Bottom line is
this is still very far out and a lot can change, but we will
need to keep a close eye on this, as some model solutions have
heavy snow totals and significant winds.

Key Message 2...
The other lesser concern is a very cold airmass especially
Thursday night into Saturday. The cold air really moves in
Thursday night, with lows around zero in the north with
potential wind chills to around -20F. Not quite as cold
Downeast, but still cold. Pretty high confidence that it stays
cold Friday and Friday night, with highs Friday around 10 in
the north and 15-20 Downeast, and lows Friday night 10 below to
5 above, with the potential of some colder readings if we clear
out with high pressure moving in. Little/no precipitation
Thursday night through Saturday, with a weather system likely
missing us to the southwest as we will be too deep into the cold
air. Can`t rule out a little light snow getting as far NE as Bar
Harbor/Bangor/Greenville, but more than likely it`ll stay to our
SW.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
NEAR TERM:
Through Tonight:
VFR. NW winds 10-15 kt with gusts up to 25 kt early, decreasing
to 5-10 kt this evening.

Tuesday: VFR with light winds.

Tuesday Night: VFR, becoming MVFR with -SN for some eastern and
northern terminals. IFR or lower possible in SN for BGR and
BHB. Winds E at 5 to 10 kt with gusts to 15 kt.


SHORT TERM:
Wednesday...Potential IFR/MVFR Downeast early Wed, with
potential MVFR early Wed in the north, but confidence is low.
Most places should become VFR by Wed afternoon regardless. N
wind 5-10 kts.

Wednesday night-Thursday...VFR Downeast with possible MVFR, and
mainly MVFR Aroostook terminals in potential snow showers and
low cigs. Variable wind 5 kts becoming NW 10 kts.

Thursday night-Saturday...Mainly VFR. NW 5-15kts.

&&

.MARINE...
NEAR TERM: Winds and seas will fall below advisory levels this
evening before increasing to advisory levels again on Tuesday
night. There is a chance (slightly below 50 percent) of
localized gales later Tuesday night, but uncertainty remains on
placement and timing of the strongest winds.

SHORT TERM: Potential NE gales Wed morning, but not enough
confidence to issue gale watch. Next chance of gales is Thursday
night, with potential freezing spray too.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory from 6 PM Tuesday to noon EST
     Wednesday for MEZ010-015-016-031.
     Winter Storm Watch from Tuesday evening through Wednesday
     morning for MEZ029.
MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ050-
     051.

&&

$$


Near Term...MWS
Short Term...TF
Long Term...TF
Aviation...MWS/TF
Marine...MWS/TF