579
FXUS61 KGYX 172015
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
415 PM EDT Fri May 17 2024

.SYNOPSIS...
A weak trough will approach northern areas this evening
bringing scattered showers to the mountains. Low pressure moving
up the East Coast will spread light showers into Maine and
eastern New Hampshire Saturday. High pressure strengthens over
the region early next week with dry conditions and above normal
temperatures. Scattered showers return by late Wednesday into
Thursday as a cold front approaches and then crosses the region.


&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Impacts:
*No significant weather impacts expected

Many areas warmed well into the 70s today which has resulted in
an expansive cumulus field over most of the area, the exception
being the coast where the seabreeze has kept things more stable.
Current radar shows storms are starting to pop up in northern
Somerset county and just over the International Border and I
would still expect some to pop up in the Western Maine Mountains
and northern New Hampshire before today`s heating is done. A
rumble of thunder with these is not out of the question as SPC
mesoanalysis suggests upwards of 500 J/kg of surface based CAPE
in that area. Otherwise, we will just be watching clouds
increase as a trough approaches from the west, currently just
getting into New York based on satellite. These increasing
clouds should largely keep low temperatures in upper 40s and low
50s. As far as fog tonight, went with the persistence thinking
as I don`t see a reason that some patchy fog wouldn`t develop in
the valleys again tonight with winds light and low level
moisture increasing. This will be especially true for the coast
as an area of low pressure moves up the East Coast now looking
close enough to push some decent moisture into the coastal
plain, so kept marine fog in the forecast which may be able to
push just inland into immediate coastal areas like Portland and
Rockland, but not much further.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Impacts:
* No significant weather impacts expected

Low pressure off at sea now looks like it will pass close
enough to spread showers into Maine and eastern parts of New
Hampshire. Unfortunately, 12Z guidance did not provide much more
confidence in the probability of precipitation. We will
certainly have clouds as we will be getting moisture advection
from both sides with the trough moving in from the west and low
pressure pushing it in from the east. Models do agree that this
moisture being advected in from the low will drive PWATs up near
1.25". However, they greatly disagree on if we will actually
get much rain out it. Mesoscale models have trended
significantly wetter over Maine with just a few scattered
showers backing into New Hampshire. Global models have continued
to be unexcited and throw just a few light showers at the
immediate coast. Due to this uncertainty, I continued with a
middle of the road approach using the likely PoP coverage of the
mesoscale models for coastal and interior areas as it seems
like that will be the best chance to see at least some light
showers. With that being said, I went very conservative with
QPF, siding more with the global models, as the mesoscale
models, that tend to over do it in these regimes, were spitting
out 0.5" to 1" amounts across the Midcoast and interior. At this
time it seems more likely that these will be lighter showers
that would be more like .10" to 0.25" with the higher amounts
being realized in those areas near the coast that see more
numerous showers. High temperatures will likely only just get
into the 60s away from the coast, with areas along the
Connecticut River Valley standing the best chance to see higher
temperatures in the upper 60s as they would be the first to see
skies clearing as the low pressure system pulls away.

With subsidence behind the trough, its likely patchy fog will
develop again Saturday night as areas clear out, especially in
areas that saw rain. As a result, low temperatures look to only
drop into the upper 40s and low 50s areawide.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Overview: Two main pressure systems will influence conditions
over the area through the long term. First will be high pressure
that maintains quiet weather overhead for the second half of
the weekend and into early next week. Second is approaching low
pressure and trough that could bring a round of widespread
rainfall to the area as well as the chance for some
thunderstorms into midweek. Temperatures are forecast to rise
for early in the week, perhaps by 10 to 15 degrees above normal
for southern portions of the area.

Details: Ridging sits over the area Sunday with more stable
conditions. While precipitation isnt expected, there will
remain moisture in the low levels that is expected to leave much
of the area cloudy. Cant rule out drizzle considering some of
the profiles looking saturated in the low levels, but any sort
of lift is limited as well. Will hold off on drizzle wording for
now, but would expect at least some patchy drizzle into the
morning and perhaps again in the evening. These conditions will
leave temperatures mild, but went slightly lower than the mean
considering the chance for cloud cover. Some breaks will be
possible on western side of the mountains, particularly in the
afternoon, so left expected highs here closer to the mean (upper
60s to around 70). With clouds expected to remain overnight,
lows are also mild falling to around 50.

Moisture layer will have thinned by the time Monday rolls
around, and currently forecast thinning clouds into the
afternoon. This should be a good start to a warming trend for
early next week with highs pushing into the mid to upper 70s.
The warmer temps arent expected until Tuesday/Wednesday when
return flow from exiting high really combines to push 850mb
temps above 10C.

Well above normal temperatures are possible Tuesday and
Wednesday next week. The area will be in between weather
systems, with high pressure sliding east and incoming trough
from the west. This should emphasize SW flow through much of the
column, resulting in good WAA. This would mean temps pushing
into the 80s for at least southern areas. NBM probabilities hint
at temps perhaps exceeding 85 degrees up the CT River Valley
and interior southern NH, but areal extent outside of those
locations isnt consistent.

Another topic for mid week will be the return of forcing,
moisture, and instability. Surface low pressure is forecast to
track up towards James Bay by Wednesday night, with an
associated warm front lifting through the region and cold front
exiting the eastern Great Lakes. This will create some favorable
conditions for rounds of showers, but also some thunder. There
remains differences in guidance to hone in on exact
timing/impacts, but can say the environment will be more
unsettled here especially on the heels of the warm/hot
conditions. The front should pass off the coastal waters towards
Friday morning, with slightly cooler temps into next weekend.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Short Term...Mainly VFR this evening with some localized
restrictions in fog at valley terminals and possibly coastal
terminals as well. Fog will dissipate Saturday morning, but
ceilings will also be lowering so improvements may only be made
to MVFR. This will be the case through the day Saturday before
skies clear again overnight Saturday. Again there will be a
chance for localized fog, but ceilings will be trending toward
VFR for Sunday.

Long Term...Ceiling restrictions expected Sunday, with mainly
MVFR and some IFR for much of the area. These remain overnight
into Monday morning, but begin to improve towards VFR into the
afternoon. Low confidence in fog/vis restrictions at this time,
but can`t rule out drizzle Sunday. VFR conditions Tues into Wed,
perhaps some overnight valley fog.

&&

.MARINE...
Short Term...SCA conditions begin to develop tonight as low
pressure moving over the eastern waters pushes 5 ft swell into
the area with winds not exceeding criteria. These elevated seas
look to last through Saturday night and begin subsiding Sunday
morning. Winds will be primarily northeasterly through this
period with gusts around 15-20 kts.

Long Term...Wave heights remain around 5ft Sunday, but will be
decreasing overnight into Monday as high pressure takes up
residence. This should lead to sub-SCA impacts to wind/waves,
but could also see some fog over water develop as warmer
temperatures enter the region into early next week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 2 AM Saturday to 10 AM EDT Sunday
     for ANZ150-152-154.

&&

$$


NEAR/SHORT TERM...Baron
LONG TERM...Cornwell