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000
FXUS61 KGYX 181929
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
329 PM EDT Thu Apr 18 2024

.SYNOPSIS...
A weak disturbance brings light rain across New Hampshire into
far western Maine through this evening. Temperatures will trend
cooler as an onshore component to surface flow builds,
culminating in the passage of a frontal system with light rain
late Friday into Saturday morning. Quiet, mild, and dry weather
returns late Saturday through early next week. Low pressure
approaches the region toward mid-week, potentially bringing the
next chance for widespread rain.

&&

.NEAR TERM /TONIGHT/...
High pressure sinks south into the Bay of Fundy tonight as
upstream low pressure passes NEward through Toledo, continuing
onshore flow for New England. This is a battle of the
airmasses... with a very dry airmass associated with the high
gradually yielding to a humid column pushing in from the
southwest by the approaching low, resulting in light showers or
sprinkles before forcing is lost late this evening. Meanwhile
at the surface, easterly to southeasterly flow off the waters
reinforces increasing humidity especially when mixing is lost
later today.

In terms of sensible weather, there will be a noticeable uptick
in humidity and clouds which will allow for more uniform
overnight temperatures across the region. Have lows generally in
the mid-30s as a result. Showers/sprinkles meanwhile will
diminish over New Hampshire. Low stratus may form over the
interior into the foothills, though this appears to be more of
an outlier solution at this tie.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Southerly flow increases Friday as low pressure tracks across the
Ottawa Valley, dragging a cold front toward New England. As a result
more of the forecast area will be under a marine influence, with
temperatures topping out in the 50s area-wide...mid-50s for most...
and limited to the 40s along the coast. The daytime is forecast to
be dry with a mix of sun and clouds. Will have to keep an eye on
any stratus formation over the interior early in the day, but as
mentioned above that seems like an outlier at this point.

Clouds increase from the west by the evening as scattered light
rain showers enter from the west. I`m not expecting everybody to
necessarily pick up light rain with this, however as the front
approaches the coast late Fri night / early Sat morning steadier
rains are forecast to develop with a subtle amplification of
the surface low. But, total amounts still look to be around a
tenth of an inch or less. The continued marine influence,
along with clouds and humidity from the frontal system, bring
our mildest overnight yet with lows in the 40s... probably right
around SST along the coast.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Overview: The 500 MB pattern shows a broad trough over the
region through the weekend into early next week, however dry air
looks to dominate overhead at the same time so not much in the
way of precipitation is expected. A more amplified trough looks
to coincide with a cold front midweek, which could be our next
chance of widespread rain.

Some light rain showers may linger into Saturday morning as a
cold front will be in the process of crossing the area. While
showers come to an end early, a 500 mb trough lagging behind the
front will provide enough forcing to keep the remainder of the
day cloudy and unsettled, especially if the front gets hung up
as well. Otherwise, breezy westerly winds will begin to dry
things out in the lower levels and help temperatures warm into
the upper 50s to low 60s south of the mountains, and upper 40s
to low 50s to the north. Skies will become clear overnight, and
with dewpoints dropping as well, low temperatures stand to drop
into the 30s across the area.

Sunday will be a very similar day temperature wise, as we start
cold and clear, then continued broad troughing overhead and
southwesterly upper level flow will allow for some diurnal cloud
cover that will cap highs in the upper 50s and 40s from south
to north respectively. Upper flow then shifts westerly and dries
out the column Sunday night making for another good looking
radiational cooling night that will drop temperatures back into
the 30s. We will begin a warming trend on Monday as upper flow
becomes more zonal and skies stay mostly clear. A cold front may
dip across the international border briefly, but with such a
dry air mass aloft it wouldn`t amount to more than a few extra
clouds across the north. Highs will be back in the upper 50s and
low 60s across the south, but more 40s up north. Clear skies
will continue the trend of lows in the 30s south of the
mountains and upper 20s for northern zones that won`t be getting
as warm during the day.

Surface low pressure looks to ride the aforementioned frontal
boundary into the region toward midweek. This would mean
increasing clouds on Tuesday, but with southwesterly flow aloft
the warming trend would continue and result in many areas south
of the mountains seeing 60s and even upper 50s to the north.
Seabreezes will continue to keep coastal areas in the 50s as
well. A deeper upper trough and cold front looks to cross
Wedensday bringing our next chance for widespread rain. Euro and
GFS ensembles have only 0.25 to 0.5" at the moment so nothing
drenching, but will continue to keep an eye on trends as this is
occuring at the tail end of the extended forecast period and
uncertainty in the pattern setup is at its usual high.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Short Term...VFR decks fill in across the region tonight with
MVFR CIGs developing mainly in southern and central New
Hampshire by morning. There is a chance that IFR/LIFR CIGs
briefly build closer to the coast based on E to SE flow off the
Gulf of Maine, however model guidance continues to shy away from
that potential in the near-term. More widespread CIG
restrictions, mainly MVFR, are expected on Fri into Fri night
with increasing S flow and -RA... and a chance of IFR/LIFR in
low CIGs/VSBY through the interior. VFR is more likely to
prevail at KHIE.

Long Term...MVFR ceilings will be the story for much of
Saturday until drier air enters the region overnight into
Sunday. VFR prevails from Sunday through Tuesday, before
ceilings begin to lower again Tuesday night. Prevailing winds
will be westerly through Monday, then shifting southerly on
Tuesday.

&&

.MARINE...
Short Term...Easterly gradient flow AOB 15 kts today deflects
southeasterly on Friday then southerly Friday night...
increasing to around 20 kts with rain showers and some fog
possible.

Long Term...Westerly winds prevail with daily seabreezes
possible through Monday, before shifting to southerly on
Tuesday. Wind gusts and seas are expected to stay below criteria
hazardous to small craft through this time.

&&

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

&&

$$

NEAR/SHORT TERM...Casey
LONG TERM...Baron