592
FXUS61 KGYX 140245
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1045 PM EDT Tue Aug 13 2024

.SYNOPSIS...
A tranquil evening is expected tonight as high pressure holds
over the area. Mostly clear skies are expected across NH and ME
tonight before some valley fog develops across portions of
western NH tomorrow morning. Scattered thunderstorms develop
tomorrow and Thursday afternoon. Some storms tomorrow may
contain small hail and gusty winds. Friday looks to be more
pleasant with storms mainly staying contained in N NH and NW
ME. After Friday, more unsettled weather is possible through
this weekend and potentially even into early next week as well.
Hurricane Ernesto passes offshore late this weekend and early
next week, bringing an increasing swell and dangerous rip
currents by late this weekend and early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
946 PM Update...
The last of the isolated showers will continue to dissipate over
the northern mountains late this evening. This will leave the
region with dry condition, albeit, patchy fog will develop,
especially in the Connecticut River Valley.

822 PM Update... Quick update to raise pops over northern
areas. A few showers may make its way across the international
border and into Maine over the next hour or two before
dissipating. This is supported by the latest HRRR and NamNest
solution.

Update...
Mainly clear skies continue this evening across the region with
with some cloudiness lingering across the northern higher
terrain. Patchy fog will develop once again tonight, mainly in
the Connecticut River Valley and mainly after midnight.
Otherwise, little in the way of changes to the near term portion
of the forecast.

Prev Disc...
Skies generally clear out of the region this evening, allowing
for a tranquil evening ahead. With a crisp and calm night ahead,
the CT river valley could see some valley fog tomorrow morning.
Some lighter patchy fog is possible elsewhere but light winds
will likely keep western and central Maine mixed, preventing the
formation of fog out there.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Tomorrow, an upper-level low positioned over eastern Maine may
bring some scattered thunderstorms tomorrow afternoon. Chances
of seeing a thunderstorm are higher across central ME and the
Midcoast, but everyone has a chance of seeing a storm. These
will likely be garden variety thunderstorms, with heavy
downpours, small hail, and perhaps a few strong wind gusts as
well. Storms will move from north to south tomorrow afternoon.
Tomorrow night, storms clear the area before fog possibly
develops early Thursday morning.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Overview...

A series of troughs move through the Northeast late this week
and through the weekend, bringing multiple chances for showers
and storms, as well as near average to seasonably cool
temperatures. Tropical storm Ernesto is expected to strengthen
into a Hurricane and pass offshore this weekend and early next
week, bringing an increasing swell and dangerous rip currents
starting this weekend.

Details...

A cutoff low deepens across Atlantic Canada on Thursday, with
multiple shortwave troughs rotating around it starting on
Thursday. With this feature, increasing clouds, showers, and
storms develop during the afternoon on Thursday, with the
greatest coverage across the higher terrain. These gradually die
off after dark. A weak shortwave ridge moves through on Friday,
bringing a brighter and relatively drier day. However, with the
cutoff low and cold pool aloft still nearby, some scattered
showers are still possible Friday afternoon, especially across
northern and eastern areas.

By Saturday, the next trough begins to dig in through the Great
Lakes. This brings an increasing chance of showers late in the
day, especially across western and northern areas. These
continue to spread eastward overnight as low pressure develops
through the Great Lakes and slowly drifts eastward. A ridge
develops and remains nearly stationary across Atlantic Canada
over the weekend. This slows and nearly stalls the system in the
Great Lakes from making much eastward progress, allowing
eastern areas to stand a better chance at remaining drier. This
pattern continues through Monday, with another reinforcing
shortwave transiting the trough going into Tuesday.

While all this is going on across the Northeast, Ernesto is
expected to become a hurricane and pass offshore this weekend
and early next week, likely passing close to Bermuda this
weekend. An increasing swell from the system is expected to
begin arriving by Saturday, with waves gradually building
through Monday, and then slowly lowering from Tuesday through
midweek next week. There remains some question as to how much
the trough across the Northeast will interact with Ernesto and
affect its track. While it`s expected to remain offshore, this
interaction will determine how close Ernesto will pass by to
New England, and the angle that it will be tracking while
offshore. These factors impact how large the waves will build
to, and the strength of the rip currents. Regardless, the long
period swell begins to arrive by Saturday, likely starting as a
2ft swell with a 16 second period, and then gradually build
through Monday. To how large remains in question and dependent
on the track distance and direction, which will be the main
question to solve over the next few days. Regardless, rip
currents begin to strengthen by Saturday and remain a concern
through at least midweek next week.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Short Term...
VFR expected the remainder of this evening. Some fog is
expected along the CT river, lower CIGs at LEB and HIE.  Confidence
is high in LIFR CIGs due to fog at LEB. Low stratus likely at HIE,
lowering HIE to IFR early tomorrow morning. Otherwise tomorrow
starts as a VFR day, but thunderstorms could bring restrictions
tomorrow afternoon with higher confidence in these lower CIGs at AUG
and RKD. More patchy fog is possible Thursday morning with low CIGs
possible across all TAF sites.

Long Term...Mainly VFR conditions are expected, but periods of
MVFR ceilings and showers are likely at times from Thursday
through early next week, especially across interior terminals
during the afternoon and evening. Nighttime valley fog is also
likely at LEB and HIE each night.

&&

.MARINE...
Short Term...
Southwesterly flow at 7-12kts with 1-3 ft seas expected this
afternoon. Winds shift to the northwest at 7-12kts by tomorrow
morning with no change in seas. Scattered thunderstorms possible
tomorrow afternoon, especially in Penobscot Bay. Outside of
convectively driven wind gusts, wind speeds should generally calm
through the afternoon. No SCAs are expected through Thursday morning.

Long Term...Weak pressure patterns prevail as broad high
pressure gives way to broad low pressure late this week through
the weekend. Hurricane Ernesto likely passes east of the Gulf of
Maine late this weekend and early next week, bringing an
increasing southeasterly swell starting by Saturday. The swell
may build to greater than 5ft by Sunday.

&&

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

&&

$$

Cannon/Clair