Area Forecast Discussion Issued by NWS Portland, ME
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FXUS61 KGYX 180811
AFDGYX
Area Forecast Discussion
National Weather Service Gray ME
411 AM EDT Mon Mar 18 2024
.SYNOPSIS...
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Cyclonic flow this week promotes breezy west-northwest flow,
temperatures trending cooler toward seasonal averages, and light
snow and rain showers driven by instability. Showers will be
mostly confined to the mountains, however, a quick-hitting
clipper will likely bring more widespread showers all the way
to the coast Wednesday into Thursday. Cool high pressure returns
late in the week, with a low potential for another system this
weekend.-- End Changed Discussion --
&&
.NEAR TERM /TODAY/...
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Low pressure over the Gulf of Saint Lawrence and high pressure
over the nation`s Heartland keeps cyclonic, westerly gradient
flow over New England today. This pattern is conducive to good
mixing with steady cold advection through the low- and mid-
levels. With a cooler airmass in place today versus yesterday
we can expect cooler highs mostly in the 30s north and 40s to
near 50 south. Somewhat gusty winds can be expected too, with
gusts in the 20-30 mph range today... becoming a bit more muted
as clouds build this afternoon.
Looking at moisture profiles, strong mixing today ought to tap
the humid mid-levels and produce a fair amount of stratocu
across the region, resulting in an overcast or broken overcast
afternoon for many. Unblocked flow ensures clouds track past
the mountains and to the coast in this case. Similarly, embedded
snow showers driven by an upper level wave will be mostly in
the mountains, however a few showers are likely to track out of
the mountains and toward the coast during the afternoon. Snow
squall parameters indicate some of these snow showers may
become intense, again mostly in the higher terrain of the north
and west... however the steep lapse rates driving instability
will also have cloud bases elevated enough to where the surface
may not see much more than flurries or sprinkles in weaker
showers.-- End Changed Discussion --
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.SHORT TERM /TONIGHT THROUGH TUESDAY/...
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Another shortwave and accompanying cold front drop down from
Canada overnight, maintaining snow shower activity over the
mountains. A loss of mixing leading to increasingly blocked flow
will however limit the degree to which these showers track into
the lower terrain. Still, some flurries and occasionally gusty
winds can be expected overnight with the front. While not
particularly well- mixed, except with the front itself, enough
gradient flow will remain overnight to keep temperatures from
completely falling out, with lows in the 20s to around
freezing.. warmest along the coast, coolest in interior valleys
that manage to decouple.
Tomorrow will be similar to today meteorological, although the
airmass in place will be a bit cooler and less humid with flow
aloft a bit more zonal. Thus, while strong mixing will produce
another breezy day with unblocked flow across the mountains, it
should have more sunshine with afternoon highs similar if not a
touch cooler than today... in the 30s and 40s. Would expect
scattered snow shower activity to persist across the mountains,
but with lesser intensity and coverage.-- End Changed Discussion --
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.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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Overview...
A trough deepens across the Northeast this weekend, bringing a
bout of cooler temperatures and at least a couple chances for
snow. A clipper system moves through the Great Lakes on
Wednesday and strengthens near the coastline on Thursday as it
moves off into the Canadian Maritimes. High pressure builds in
for late in the week, and then a coastal storm likely develops
south of the region next weekend.
Details...
The clipper system approaching on Wednesday presents the best
chance for accumulating snowfall across much of the forecast
area this week, with the greatest chances across northern and
western locations. Wednesday itself looks mild ahead of the
system, with highs warming into the 40s in most spots. Temps
then quickly drop as precip approaches and temps fall to near
the wet bulb temps. Showers likely start to arrive into
northwestern areas late in the day on Wednesday, while waiting
until the overnight hours to expand farther southward and
eastward. Precip may start out as rain showers, but would change
to snow showers soon after as the temps cool.
The system will likely develop a second low pressure center in
the Gulf of Maine by late Wednesday night and Thursday. This
will bring a more steady shield of snow, but exactly where this
tracks and how quickly it strengthens remain big questions.
There would also likely be an area between the two lows that
sees very little in the way of precip, so this will need to be
sorted out as well. These systems in recent memory have a
tendency to be a little bit slower to develop and result in an
over-forecast of precip. While it`s still too early to say that
will be the case with this one, both POP and QPF have been
restrained in this forecast to account for the uncertainty.
The low then moves into New Brunswick on Thursday with high
pressure building in behind it. Gusty winds are likely on
Thursday behind the system, and these may linger into early
Friday as well. By late Friday and into next weekend, high
pressure will set up across New England as a strong low pressure
center develops near the Carolina coast. Right now the bulk of
this system looks to remain south of New England, but there is a
chance some moisture could press further north, but will
struggle with the high in place. There is still a low chance
this low could track further north along the coast, but the high
would have to trend weaker and further north to make this
scenario happen. Another weak shortwave may try to move eastward
in the presence of the high next weekend as well, but this
would likely be a minor feature.-- End Changed Discussion --
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.AVIATION /07Z MONDAY THROUGH FRIDAY/...
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Short Term...VFR, except developing MVFR at KHIE, prevails
across the region for today with broken to overcast decks during
the afternoon. Brief VSBY restrictions will be possible in SHSN
anywhere however the best odds for this to happen remains at
KHIE and other mountainous terminals... at around 40 percent.
Winds gust to around 20-25 kts out of the west, strongest this
morning. Steady W flow continues into tonight, turning NW with a
crossing cold front with VFR/mtn MVFR continuing. VFR on
Tuesday with WNW winds gusting 15-25 mph.
Long Term...VFR conditions are expected most of Wednesday, and
then a period of IFR is likely with periods of snow showers
Wednesday and Thursday at most terminals. Gusty westerly winds
of up to 35kt are possible Thursday afternoon. VFR conditions
and easing winds are likely for Friday, with another chance for
some rain or snow showers over the weekend.-- End Changed Discussion --
&&
.MARINE...
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Short Term...Westerly flow persists across the waters today
through tomorrow, with sustained winds mostly hovering between
12 and 18 kts. Gusts upwards of 25 kts are possible at times,
with greatest confidence and coverage existing off the Midcoast
today... and likely everywhere as winds turn slightly NWerly
with a cold front crossing later this evening and overnight.
Seas meanwhile are expected to be hovering around 3-5 ft...
lower yet along the southern coast, and up to around 6 ft near
Matinicus.
Long Term...Low pressure approaches the waters on Wednesday,
with the low then strengthening in the Gulf of Maine late
Wednesday night and Thursday. Westerly gales are possible behind
this low Thursday afternoon and night as the low moves into the
Canadian Maritimes. High pressure then builds across the waters
late in the week behind the low. Low pressure develops south of
the waters off the Carolina coast next weekend.-- End Changed Discussion --
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None.
NH...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ150-
152.-- End Changed Discussion --
&&
$$
NEAR TERM...Casey
SHORT TERM...Casey
LONG TERM...Clair