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026
FXUS61 KCAR 211852
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
252 PM EDT Sat Sep 21 2024

.SYNOPSIS...
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High pressure will build from eastern Canada through Sunday
while low pressure in the open Atlantic drifts further out to
sea. High pressure will crest over the area Monday then retreat
into the Maritimes Tuesday and Wednesday.
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&&

.NEAR TERM /THROUGH SUNDAY/...
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A Rex block remains over the area with upper level high pressure
over northern Quebec and low pressure spinning in the open
Atlantic southeast of Cape Cod. The trend in the next 24 hours
will be for the low to continue drifting further southward while
surface high pressure builds southward from Labrador. This means
continued dry weather and cool temperatures.

Cooler temperatures at 850mb and 925mb continue to advect into
the area from the east. Lows tonight will be similar to last
night in the north as clearing skies produce a shallow radiation
inversion and fog over the Saint John and Aroostook River
valleys. Less cloud cover and wind should generate lows at least
5F cooler than last night in southern zones.

The northeasterly flow induced by the pressure centers will
continue over the area through Sunday. That ensures plenty of
low level moisture for more cumulus/stratocu fields to develop
Sunday under the subsidence inversion. There will be less high
level cloud cover than today
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&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
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High pressure remains the dominating feature for the short
term, with temperatures a little cooler than they have been, due
to the colder air mass that moved in from Canada last week.
Sunday night will be slightly cooler, since Monday will bring a
thicker layer of clouds, which should limit the radiational
cooling overnight. Overall this period will remain dry with
seasonable temperatures and light northeasterly winds.
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&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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High pressure continues through Tuesday night, but by Wednesday
afternoon the pattern will begin to shift. The upper level
ridge will move eastward, allowing a trough to move in, bringing
precipitation across the area. Confidence is stronger that the
pattern will shift, however what will happen with the low/trough
that moves in is less certain. Model ensembles have a number of
different solutions, muddying the forecast for the end of the
week. This partially depends on how deep the upper level trough
becomes and whether it becomes negatively tilted, with a closed
upper level low forming somewhere over southern Canada or the
Midwest. There is potential for a surface low to develop over
the mid-Atlantic, moving northward and enhancing any precip that
falls Thursday and Friday. Deterministic runs of EC and
Canadian also show differences in whether the surface low
develops close to the coast and brings heavier bands of precip
onshore, or moves offshore more quickly. Given these differences
in the model runs, decided to keep pretty close to the previous
forecast for the Thursday through Saturday time period, keeping
precip over Maine longer than the NBM would indicate.
Temperatures will remain seasonable through the period.
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&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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NEAR TERM: VFR conditions continue until late tonight when MVFR
tempo IFR conditions due to cig/vis develop for all sites. Any
fog will burn off quickly Sunday morning while MVFR cigs may
persist through the morning. All sites are expected to be VFR
Sunday afternoon. Light northeast winds will persist through
Sunday.

SHORT TERM:
Sunday night through Tuesday...VFR with light northeasterly
winds becoming southerly.

Tuesday night through Thursday...MVFR developing with -SHRA.
Light E to SE winds.
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&&

.MARINE...
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NEAR TERM: The Small Craft Advisory will continue into Sunday
midday due to northeast winds gusting up to 25 kt and seas near
5 ft offshore of Hancock County.

SHORT TERM: Winds remaining below 25kts for the duration. Seas
will be 1 to 3 feet through Thursday evening. The next
possibility for higher seas developing will be late Thursday
night with the movement of the surface low.
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&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until noon EDT Sunday for ANZ050-051.

&&

$$


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