Penobscot, Maine Weather Forecast Discussion

730
FXUS61 KCAR 211344
AFDCAR
Area Forecast Discussion
National Weather Service Caribou ME
944 AM EDT Sun Sep 21 2025
.SYNOPSIS...
High pressure slowly exits to the south and east through Monday. A
cold front approaches from the northwest Monday night. This front
then slowly pushes south into the Gulf of Maine through Tuesday
night, then stalls out through Wednesday, as waves of low pressure
ride along the front. Meanwhile, high pressure builds in from
southeastern Canada Wednesday and Thursday.
&&
.NEAR TERM /THROUGH MONDAY/...
945 am update...
Quick update to remove frost and fog fm the forecast. Temps
dropped below freezing over northern areas with the frost/freeze
program having ended in northwest Maine for the season as of
this morning. Sunny skies will bring high temps up toward normal
in the middle to upper 60s areawide. Minimum RH values once
again drop to between 30-40% but winds will be fairly light
under high pressure so although fire wx concerns still remain
they are not as elevated as the previous 2 days.
Previous Discussion blo...
This morning will begin cold and frosty as high pressure crests
over the area. High pressure will slide southeast of the region
today allowing a return southwesterly flow to usher in some
milder air. This will allow high temperatures to reach the mid
to upper 60s under a sunny sky.
High pressure will continue to the east tonight as a light south to
southwesterly flow continues behind the high. This will bring a
milder night than recent nights with lows generally in the low
to mid 40s. A few of the colder valleys in the northwest may dip
into the upper 30s. A few high clouds may begin to stray into
the area overnight ahead of a weak trough approaching from the
west.
High pressure will continue moving east into the open Atlantic
Monday as a weak open shortwave trough approaches from the west.
This will bring some increasing cloudiness over the northwest while
Downeast stays mostly sunny. The return southwesterly flow behind
departing high pressure will continue to usher milder air into the
region with inland highs making a run for 70 Monday afternoon.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
The region is under west-southwest flow aloft Monday night, with
shortwaves embedded in the flow bring the threat of some showers,
mainly across the North. Lows Monday night should be around 5-10
degrees above normal.
A very positively tilted northern stream trough approaches Tuesday
then builds into Maine Tuesday night. Models do differ on how far
south the trough gets Tuesday night, with some models bringing the
axis all the way into the Gulf of Maine and others hanging it up
over Northern Maine. How far south this trough gets depends on how
much it remains attached to a closed low that most models develop at
its base over the eastern Great Lakes Tuesday night. For now have
taken a middle of the road approach something similar to the
CMC- Reg. This focuses showers more over the North Tuesday, then
over Downeast Maine Tuesday night.
Note throughout this time frame, the models differ on the coverage
and intensity of the showers. For now have leaned towards the lower
end of the qpf distribution, with amounts around 2-3 tenths, except
3-5 tenths near the Downeast coast. Confidence in these values is
low at this time. However confidence is fairly high that there will
be little to no (and more likely no) hydrologic impacts from this
rainfall.
Highs Tuesday should be around 5 degrees above normal and lows
Tuesday night around 5-10 degrees above normal.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The models then differ in their handling of the developing
closed low over the eastern Great Lakes, some have it separate
from the main northern stream flow and head south into the Ohio
Valley, then eastward into the Central Appalachians. Others
take it steadily eastward, with another cutoff low then moving
in behind it into the Ohio Valley. All of these ideas seem
plausible, so unfortunately none of them can be ruled out at
this time. The resulting solutions range from dry (other than
some lingering rain Wednesday) to another slug of precipitation
coming up late in the week. For now have chance pops over most
of the area Wednesday, then over just Downeast Maine Wednesday
night. Otherwise have mainly slight chance pops Thursday-
Saturday due to the uncertainty.
Temperatures should range from near to slightly above normal
Wednesday-Saturday. Given the high uncertainty in the pattern in
this time frame, there is a lower degree in confidence than
normal in the temperature forecast.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: High confidence in VFR through the TAF period. Light
and variable winds become SW at northern terminals and S at
southern terminals at 10KT or less around midday. Winds become
light and variable again at all terminals this evening.
Monday...VFR. SSW-SW winds G15-20KT possible.
SHORT TERM:
Monday night-Tuesday...MVFR or lower possible at northern
terminals, VFR at southern terminals. SSW-SW winds G15-20KT
possible Monday evening.
Tuesday night...MVFR or lower possible at northern terminals
and probable at southern terminals. N 5kts.
Wednesday...VFR at northern terminals with MVFR possible at
southern terminals. NE-E winds G15-20KT possible Wednesday
morning.
Wednesday night...VFR.
Thursday...Most likely VFR, with a very low chance of MVFR or
lower.
&&
.MARINE...
NEAR TERM:
Winds will be light and seas around 1 to 2 ft today then 2 to 3
ft tonight and Monday. Vsby should be good.
SHORT TERM: A relaxed pressure gradient over the waters Monday
night-Thursday should limit sustained winds to 10 kt or less.
Persistent SE swells could bring wave heights as high as 5 ft to
the coastal ocean waters Tuesday-Wednesday, otherwise seas
should be 4 ft or less Monday night-Thursday.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Bloomer/Buster
Short Term...Maloit
Long Term...Maloit
Aviation...Bloomer/Maloit
Marine...Bloomer/Maloit

NWS CAR Office Area Forecast Discussion