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000
FXUS61 KGYX 131923
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
323 PM EDT Sun Oct 13 2019

.SYNOPSIS...
Low clouds and patchy fog will increase again tonight, lasting
into Monday, mainly on the coastal plain and inland Mid Coast.
A vigorous low pressure system is likely to move across the
forecast area starting Wednesday, and may allow for a period of
heavy rain and windy conditions Wednesday night into Thursday.
High pressure will slowly build over the region from the west
Friday and into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Mid-level ridging provides a nice day locally with temperatures
climbing a couple degrees above average and some Mid Coast
cloud cover. Meanwhile further west, a strongly forced closed
low churns over the Great Lakes region and central Ontario.
Tonight, heights aloft begin to fall as a shortwave axis rotates
around the closed low toward New England. Hires guidance
including the HREF continues to suggest onshore low-level
flow/weak positive moisture advection developing overnight with
high pressure moving offshore.

This will likely lead to a blanket of low stratus and fog by Monday
morning along coastal NH and ME, further into the coastal plain in
ME with greater southerly component to flow. Temperatures are a bit
tricky tonight; decoupling is likely early on, leading to quick
cooling after sundown, but then cooling slows or is halted
altogether with moist onshore flow. Therefore, coolest readings
in the 30s and perhaps fog will likely be in sheltered valley
locations of the north and into portions of the Connecticut
River Valley. Warmest readings are likely in coastal ME/NH.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
Southwest flow increases, as will available moisture, in
response to an approaching shortwave trough Monday. This ought
to lift ceilings in the morning, however widespread status to
stratocu cover is expected persist through much of the day.
Moisture convergence may be strong enough to produce a brief,
light shower on the Mid Coast in the early afternoon. Modestly
higher dew points work in through the day, as does warmer 850mb
temps at 5-7C, however cloud cover will be the determining
factor for high temperatures tomorrow. Should breaks in the
clouds allow for mixing and solar insulation, temperatures could
easily increase into the low-70`s across the south. Don`t have
a ton of confidence in cloud breaks tomorrow however so stuck
fairly close to a raw model consensus with higher values closer
to MOS guidance across southern NH where cloud breaks are more
likely.

While deep moisture remains offshore and to the southeast, enough
forcing along a crossing cold front Monday evening into the
overnight could still produce a few light showers especially across
the north and in the mountains of ME/NH. Models and WPC eke out
only a tenth or two of rain with the crossing front.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
High pressure will briefly build over the region Tuesday. This
will allow for mainly sunny and dry conditions. Temperatures
will be seasonable for mid October, mainly in the 50s.

All eyes then shift towards low pressure moving east from the
Great Lakes Tuesday night into Wednesday. 12Z model suite and
ensemble solutions continue to a secondary area of low pressure
over the Mid Atlantic states late in the day Wednesday. This
system will track off the New Jersey coastline Wednesday
evening, before racing into southern New England Wednesday
night. During this period, rapid cyclogensis occurs with the
low plummeting to around 975 mb by the time the center reaches
approximately Portland, Maine by early Thursday morning.

Heavy rain will fall along and to the left of the H7 and surface
low. One to two inches of rainfall expected, however locally
higher amounts are possible over the east facing mountains. The
Canadian model QPF is at the high end of the spectrum, likely
because its track is slightly further east then other model
solutions, therefore any dry slotting is delayed.

Cloud cover will keep temperatures in the 50s for daytime highs
on Wednesday. Cold air advection under gusty westerly winds will
keep temperatures in the mid 40s to mid 50s for high
temperatures from north to south on Thursday. Breezy conditions
will continue into Friday as the low slowly exits through the
Canadian Maritimes.

Thereafter, high pressure will build into the region over the
weekend. This will allow for dry conditions and moderating
temperatures.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Short Term...
VFR prevails with light winds for the remainder of today. Tonight,
most guidance has consistently pointed toward low stratus
development as a likelihood especially over the Mid Coast with
weak, moist onshore flow as high pressure shifts into the Gulf
of Maine. While some radiation fog is expected to develop
tonight over the Connecticut River Valley, patchy dense fog and
MVFR or worse (IFR near dawn) ceilings are more likely to
develop at coastal and Mid Coast terminals. MVFR, and some brief
instances of IFR, ceilings may linger through the day with
scattering likely in the afternoon. Then, a cold front crosses
tomorrow night with improving conditions to follow as high
pressure nudges in from the west

Long Term...Increasing clouds expected on Wednesday with rain
arriving from west to east Wednesday evening. Will likely see a
period of IFR conditions and moderate rainfall along with some
wind shear. This ends from west to east early Thursday morning
as low pressure moves east. Behind the low expect gusty west to
northwest winds of 25 to 30KT especially Thursday morning.
Otherwise, we should see conditions improving to MVFR and VFR
Thursday and Thursday night, with the lower conditions lasting
longest in the mountains.

&&

.MARINE...
Short Term...Waves and swells continue to come down tonight
with remaining SCAs on track to expire this evening. Light
northwest winds turn variable to southerly tonight, becoming
southeasterly onshore at 5-15 kts by Monday evening as a wave
aloft and associated cold front approaches. The front crosses
Monday night with a switch to westerly winds to follow.

Long Term...High pressure crests over the Gulf of Maine on
Tuesday. The next low pressure system tracks up the East Coast
on Wednesday and strengthens rapidly when it reaches the Gulf of
Maine Wednesday night. Expect southeasterly winds to back to the
northeast Wednesday night. Gale force westerly winds possible on
Thursday behind the departing low.

&&

.HYDROLOGY...
Low pressure will undergo rapid intensification as it moves
quickly to the northeast Wednesday night. One to two inches of
rain will be likely as the surface and H7 moves from southern
New England to southern Maine. Some of the east facing locations
across the higher terrain of the headwaters may have locally
higher amounts. This precipitation in such a short amount of
time may allow for rapid rises on a few of our rivers.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory for hazardous seas until 6 PM EDT
this evening for ANZ150-152-154.

&&

$$
Casey/Cannon