Area Forecast Discussion
Issued by NWS Portland, ME

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766
FXUS61 KGYX 291138
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
738 AM EDT Mon Apr 29 2024

.SYNOPSIS...
Mostly clear and dry today as high pressure builds into the
region. A frontal system approaches from the west on Tuesday
bringing showers Tuesday night into Wednesday. Ridging builds
over the eastern US during the second half of the week, although
disturbances moving over the ridge will bring chances for
showers into the weekend. A gradual warming trend looks to start
this weekend into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
735 AM...Forecast in good shape, just made a few adjustments to
T/Td and sky through the morning, but most places should see a
period of mostly sunny skies later this morning and this
afternoon.

Previously...Weak sfc cold front should be offshore by daybreak
with main change behind this front being lower Tds, and wind
shift, to the N. Seeing some signs of sfc wind going N-NW but
generally light outside of the mtns, and may take until mixing
shortly after sunrise to mix the winds and drier air down to the
sfc, as is often the case. Also starting to see clearing across
much of the CWA and this should continue through the morning. I
think most places, even the mtns should see mostly sunny skies
for a good chunk of the day, may see more clouds moving back
into S NH later today as the front starts to shift back N in
response to approaching trough from the W. Highs today range
from around 60 in the mtns to the low 70s in S NH. After the
surge of N winds this morning winds will actually diminish
enough for a late sea breeze to develop which will keep the
coast cooler.

&&

.SHORT TERM /TUESDAY/...
For tonight that 500 MB wave will crash into the ridging over
the NE CONUS, and while clouds will overspread the area, this
will mainly be mid to high clouds for much of the night, as the
dry lower levels will hold much of the night. Theres a low
chance that some coastal stratus develops, in a few spots, but
this more likely later in the day Tuesday. Lows range from 35-40
in the mtns to the low to mid 40s elsewhere.

NE flow gradually shifts more E on Tuesday, and this will lower
maxes by about 10 F from Monday. Itll also be mainly cloudy
through the day although the ridging holds pretty well and keeps
most of the area dry. The only exception is the possibility for
a few showers in the CT valley in the afternoon Tuesday, as that
wave does tamp down the ridge a bit and coincides with some of
the better mid level WAA. Highs range from the low to mid 50s in
may spots across ME and the mtns to the low 60s in interior S NH
and the CT vly.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Overview: May is going to start out unsettled as the 500 mb
pattern features multiple shortwaves and then an upper low
closing off over the North Atlantic, which will continue to
rotate shortwaves through the region. This would keep chances of
showers in the forecast through much of the extended before
ridging maybe builds back in for the weekend, but there is some
uncertainty in just how amplified it would be.

Impacts:
* No significant weather impacts expected

Details: Low pressure crossing the area along with upper level
divergence as we find ourselves in the right entrance region of
a low level jet, will keep showers going through the overnight
hours into Wednesday. With onshore flow low temperatures are
likely to cool well into 40s across the area, with areas in the
coastal plain even dipping into the 30s. Southwesterly upper
level flow will drive PWATs toward the 90th percentile over the
area, around 1", but current Euro and GFS ensembles, and
surprisingly even the latest NAM only show amounts around 0.25".
This is likely owing to the progressiveness of the system and
the fact that we will see drier air intruding later in the day.
However, this does look like a situation where some of these
showers end up convective resulting in isolated downpours that
put down a quick 0.5" or more, this is hinted at in the 00Z NAM
nest. With continued onshore winds and mostly cloudy skies
temperatures look to only warm into the 50s areawide with the
coolest temperatures once again in the coastal plain. Clouds
will begin to break up Wednesday night as upper level ridging
looks to briefly build in turning upper level flow more
northwesterly and getting drier air into the column. 850 mb
temperatures remain warm so despite some clearing we likely end
up with overnight lows similarly in the 40s.

Thursday looks to be mostly dry, but shower chances will
quickly come back into play as ridging breaks down and a
vorticity maxima crosses the area. With upper level flow still
northwesterly, sensible weather may be limited to just increased
clouds, but a few sprinkles can`t be ruled out at this time.
This has resulted in guidance trending a bit cooler with low to
mid 60s across most of the area, upper 50s along the coast, and
upper 60s in southern New Hampshire. Friday will be nearly
identical as models close off a 500 mb low in close proximity to
the northeast, but again with limited moisture the result is
likely just more clouds and cooler temperatures.

Saturday and Sunday may see us under a ridge axis once again,
but not all models agree. The 00Z Euro has come in with a well
amplified ridge, while the GFS and Canadian are not so excited
and have a less amplified and shortwave ridden pattern. Time
will tell, but for now will stick with the NBM this far out.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Short Term...Any lingering fog and low cigs, mainly at KLEB,
should clear by sunrise with VFR expected today into much of
Tuesday. Coastal stratus may move in mid to late afternoon but
should only affect coastal terminals before Tuesday evening.

Long Term...MVFR ceilings are expected with rain showers moving
through the area Tuesday night into Wednesday morning. Ceilings
should gradually lift becoming VFR by Wedensday afternoon. MVFR
ceilings are possible once again on Thursday, mainly across the
north, otherwise VFR prevails through Friday.

&&

.MARINE...
Short Term...Despite a brief burst of increased N winds today,
winds/seas expected to remain below SCA levels through Tuesday.

Long Term...Conditions hazardous to small craft are not expected
through Friday. Winds will be primarily onshore with shifts to
northerly Wednesday and Thursday night as systems pass over the
waters.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$

SYNOPSIS...
NEAR TERM...Cempa
SHORT TERM...Cempa
LONG TERM...Baron
AVIATION...
MARINE...