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000
FXUS61 KCAR 181041
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
641 AM EDT Thu Apr 18 2024

.SYNOPSIS...
High pressure crosses the region today and moves east of the
area by Friday. An occluded front approaches later Friday,
crosses the region Saturday, then exits across the Maritimes
Sunday. High pressure builds toward the region Monday into
Tuesday. A frontal system approaches the area Tuesday night
into Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
641 AM Update: Current satellite imagery shows that aside from
thin cirrostratus stretching from the North Woods down through
coastal Hancock county, sunny skies are in abundance this
morning across the forecast area. Only minor adjustments made to
the previous forecast based on observations as the previous
forecast remains on track.

Previous Discussion:
High pressure remains over the area today, which will slow the
progression of the next low pressure system approaching from the
southwest. Subsidence under this high pressure will finally act
to keep winds fairly light through the day. Since there is a
low approaching from the southwest, cloud cover will return
through the day from the west, especially at mid to upper
levels. That said, given the synoptic setup, mid to upper level
clouds will likely be thin through most of the day. High
temperatures will lift into the mid 50s across much of the
forecast area. The immediate coast is likely to see a sea breeze
this afternoon due to light winds and clear skies along the
coast, which will limit how warm it gets and may result in a
localized line of cumulus clouds.

Tonight, skies will continue to cloud over, such that even
though winds will approach calm once more, full radiational
cooling will be limited, and lows will only fall into the low to
mid 30s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Surface and upper level ridging remains over the area Friday
morning. The ridging moves east later Friday...allowing
increasing clouds ahead of a weakening occluded front. Before
the clouds increase, warm advection will push highs towards the
mid to upper 50s across northern zones. 925mb temps will
increase towards 5C to 6C. Onshore southerly winds will keep
highs closer to 50F along the coast. Southerly winds will become
increasingly gusty later in the afternoon with speeds up to 25
mph.

The best forcing with the occlusion will pass well to the north
and west of the area and current expectations for precipitation
range from nothing to just a few hundreds of an inch. The front
may be reinvigorated in the Gulf of Maine later in the night as
a separate shortwave propagates eastward from the Great Lakes
region. There is some uncertainty in how this energy is
manifested over the Downeast region on Saturday. The latest
ECMWF strengthens the occlusion boundary and causes a fairly
rainy Saturday for coastal Washington County. Other guidance
such as GFS/NAM/GEMS strengthens the occluded front south of
the area, but surface-based instability develops Saturday
afternoon from Bangor towards the Downeast region as a cold
front sweeps down from the north and a cold upper trough
provides strong cooling aloft. This latter scenario could
generate some fairly good late afternoon downpours Downeast and
maybe even a thunderstorm or two with graupel.

Highs on Saturday will reach the mid to upper 50s for most of
the area. The coast will be cooler with another day of onshore
winds.  Cannot rule out a few 60F readings around Bangor.

Much colder and drier air sweeps into the area behind the cold
front for Saturday. Any remaining shower activity will end in
the Downeast region. Temperatures will drop towards the mid 30s
with clearing skies.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Expect shortwave ridging over the area on Sunday. The air mass
looks too dry to support much in the way of precip, but there is
sufficient moisture in the H8 layer to support cumulus fields
above a very deep mixed layer. Given this expectation, increased
highs a bit above guidance, dropped dew points below guidance
and increased wind gusts.

A dry northern stream cold front to move swiftly across the area
on Monday with a reinforcing shot of cool and dry Canadian air.
Afternoon dew points may drop into the low teens in Aroostook
County. Once again, expect a very deep mixed layer behind the
front with corresponding actions on hi temps, winds and dew
points.

The cool Canadian high pressure behind the front and decreasing
winds/clouds will likely produce lows in the upper 20s to lower
30s on Monday night.

The high will remain in control over the area on Tuesday, but
some air mass moderation will push hi temps back towards the mid
to upper 50s. Expect a trend towards increasing clouds in the
afternoon ahead of the next frontal system.

Things become much more complicated for Tuesday night into
Wednesday. A clipper system arrives from the Great Lakes. Most
of the latest guidance suggests the emergence of a strong
baroclinic zone over the area with an anomalously cold upper
low swinging south from Hudson Bay. Snow is certainly a
possibility given the availability of cold air, but it hinges on
how two upper lows phase a week from now. One of which is
currently in the Pacific Ocean and the other is near the North
Pole. For now, capped PoPs at chance and am going with temps
more supportive of rain on Wednesday.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
NEAR TERM: VFR conditions continue through today and tonight.
Winds light and variable through the early morning hours,
becoming E to NE around 5 kts this afternoon. A sea breeze will
lead to coastal terminals up through KBGR to shift southerly
this afternoon. A few cumulus are expected to develop over the
area this afternoon, but cigs will remain VFR. VFR cigs with
mid-level stratus moving in tonight, and winds light and
variable.

SHORT TERM:
Friday...VFR with south winds 10 to 20 kt by afternoon.

Friday night into Saturday morning...MVFR cigs tempo IFR cigs.
LLWS possible. South winds 10 to 20 kt...becoming southwest
Saturday morning.

Saturday afternoon through Monday...VFR. Southwest winds 15 to
25 kt on Saturday afternoon will become westerly on Sunday and
Monday at speeds of 10 to 20 kt.

&&

.MARINE...
NEAR TERM: Winds/seas below small craft advisory levels
today through tonight.

SHORT TERM:
Fog is possible over the waters later Friday night into Saturday
morning. Otherwise, no high impact weather is expected in terms
of wind or seas through early next week.

&&

.FIRE WEATHER...
A prolonged period of dry weather with low relative humidity and
gusty winds is expected through Tuesday. A wetting rain is not
expected Friday night into Saturday. The next potential rainfall
occurs next Wednesday, followed another round of dry days with
low relative humidity.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.

&&

$$


Near Term...AStrauser
Short Term...MCW
Long Term...MCW
Aviation...AStrauser/MCW
Marine...AStrauser/MCW
Fire Weather...