-- Discussion containing changed information from previous version are highlighted. --
455
FXUS61 KCAR 212227
AFDCAR

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

.SYNOPSIS...
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.
&&

.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
Update...
High pressure centered near Labrador will ridge south across
the forecast area tonight, while a slow moving ocean low
southeast of Cape Cod drifts southeast. Expect partly/mostly
cloudy skies across northern portions of the forecast area
tonight. Could also have patchy, mostly river valley, fog later
tonight. The northern edge of the cloud shield from the ocean
low will keep mostly cloudy skies Downeast. Low temperatures
tonight will generally range from around 40 to the lower 40s
north, though upper 30s are possible in the normally coldest
locations. Expect lows in the mid 40s interior Downeast, with
upper 40s to around 50 along the Downeast coast. Have updated to
adjust for current conditions along with expected overnight
temperatures and clouds.

Previous Discussion...
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.

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
-- End Changed Discussion --
&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
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.
&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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.
&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
NEAR TERM: Variable conditions with any patchy fog late tonight
through early Sunday across mostly northern areas. Occasional
MVFR ceilings also possible late tonight through early Sunday.
Otherwise, VFR tonight through Sunday. East/northeast winds 5 to
10 knots tonight 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.
-- End Changed Discussion --
&&

.MARINE...
-- Changed Discussion --
NEAR TERM: A Small Craft Advisory remains in effect for much of
the waters, with the exception of the intra-coastal waters,
tonight through noon Sunday.

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.
-- End Changed Discussion --
&&

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

&&

$$


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