839
FXUS61 KCAR 180134
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
934 PM EDT Sat Aug 17 2024

.SYNOPSIS...
Surface high pressure drifts east of Nova Scotia tonight.
Ernesto will track well east of the region Sunday through
Monday. Low pressure will also approach from the west Monday,
cross the region Monday night through Tuesday, then exit across
the Maritimes Wednesday while high pressure begins to build into
the area on Thursday.

&&

.NEAR TERM /THROUGH SUNDAY/...
930 PM Update... No significant changes were needed with this
update. Cloud cover continues to increase, particularly across
the southwestern portion of the forecast area as southerly flow
continues. With the increasing cloud cover, fog will be more
influenced by advection rather than radiation tonight, and is
expected to be mostly confined to Downeast areas and south
facing slopes further inland. It remains hazy across the area
due to smoke, mainly aloft, from distant wildfires. However,
slightly higher surface smoke concentrations exist across the
Saint John Valley.

Previous Discussion...
Tonight high pressure will drift E of Nova Scotia as a 500mb
upper low works into the Eastern Great Lakes. Return southerly
flow increases and turns S-SSE over the area with moisture
advecting northward. RAP/HRRR vertically integrated smoke
models continue to show haze caused by smoke continuing through
tonight into Sunday morning. Expecting patchy to areas of fog
to develop again tonight and may become dense along the Downeast
coast given the wind direction flow turning S-SSE & boundary
layer moisture increases. Temperatures fall back into the upper
50s to low 60s across the area with calm or light and variable
winds. Sunday will turn partly sunny after morning fog but
expecting smoke to dissipate with increasing SW flow aloft
pushing it mostly out of the area. Expecting more stubborn
clouds Sunday with highs generally in the low to mid 70s and a
touch more humidity. Cool spots along the Downeast coast will
only reach the mid to upper 60s. A few showers will be possible
along the Quebec border by afternoon, perhaps dipping down into
the Moosehead Region, which is ahead of our next weather maker
described below. Lastly, main concerns is from Ernesto causing
increasing wave heights making it to the coast and rip current
risks increasing which is talked about in the Marine section
below.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As Ernesto moves further northwards, well to the east of the
forecast area, the system will begin to transition to an
extratropical system, which in part would be seen by the
expansion of the wind field and circulation. The core of the
system will remain completely out of our region, passing east of
the Canadian Maritimes, however, recent model runs suggest that
as Ernesto transitions, moisture from this expanding system may
get wrapped around the stalled ridge of high pressure over the
CWA, leading to increased moisture and cloud cover through
Sunday night into Monday ahead of the next frontal passage.

As the next longwave trough begins to slide eastward into the
area on Monday, the left exit region of a jet streak aloft will
aid in providing lift for scattered showers across the area,
capitalizing on the additional moisture provided from Ernesto as
outlined above.

For Monday night into Tuesday, a cold front will finally,
slowly, push through the area as the blocking pattern begins to
release with Ernesto moving east and the ridge of high pressure
sliding eastward in pursuit. An upper level longwave trough,
with connections to deep Gulf of Mexico moisture, will support
the surface low and cold front, bringing the next widespread
rain event to the region.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The upper level trough remains in the area through the middle of
the week, which will persist a general area of instability and
lead to the slight chance for showers to linger Tuesday night
into the day on Wednesday. That said, plenty of dry air will be
ushered in aloft, which will limit how extensive rain showers
may become through the middle of the week. High pressure is likely
to return by the end of the week, but some uncertainty remains
in how deep the ridge of high pressure will be, with a few
models resolving a more progressive pattern and another
shortwave moving into the region by the end of the week.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: Already IFR at BHB and expected to become MVFR/IFR
tonight with LIFR possible due to low ceilings and visibility at
all airfields. BR/FG and low ceilings are likely at BGR and
Downeast airfields. Ceilings and visibility improve to VFR at
northern airfields and MVFR and BGR and Downeast airfields by
midday Sunday. Winds S around 5kts becoming light and variable
tonight, increasing to 5-15kt Sunday.

SHORT TERM:
Sunday night...Variable conditions with low clouds and patchy
fog late. Otherwise, VFR. A slight chance of showers across
western areas. South/southeast winds 5 to 10 kts.

Monday...Variable conditions with low clouds and patchy fog
early, then VFR/MVFR. Increasing shower chances.
South/southwest winds 5 to 10 kts.

Monday night...IFR likely across all terminals with rain and a
slight chance of thunderstorms. Winds shifting NW at 5 to 10 kts.

Tuesday...IFR early, potentially improving to MVFR through the
day. Rain, tapering to showers. NW winds 10 to 15 kts.

Tuesday night...VFR/MVFR. A slight chance/chance of showers.
North/northwest winds 5 to 10 kts.

Wednesday...VFR. Slight chance of a shower. North/northwest
winds 5 to 10 kts.

Thursday...VFR across all terminals. Light NW winds around 5
kts.

&&

.MARINE...
NEAR TERM: Ernesto tracking well E of the waters through Mon is
causing long period swells of 12-15 seconds to continue
building tonight. Small Craft Advisory has gone into effect for
the Coastal Waters out 25nm and East to the Hague Line. S swells
will increase to 6-7ft tonight. Areas of fog will reduce
visibility tonight. Sunday, wave heights will increase to 5-8ft
at 14-15sec periods. These waves will reach the Downeast coast
posing a serious concern for dangerous high surf hitting the
coast and rip currents. High Surf Advisory will be in effect
from 8PM tonight through Monday night. Sea surface temperatures
from the Downeast coast out 25nm and east to the Hague Line
range from 55-60F including Passamaquoddy Bay.

SHORT TERM: A Small Craft Advisory is in effect through Monday
due to seas from swells generated from Ernesto. Meanwhile,
Ernesto will pass well to the east of the waters. Seas 4 to 7 ft
may linger into Monday night as well. A chance of showers
Monday, then rain Monday night into Tuesday. Patchy fog Sunday
into Tuesday.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...High Surf Advisory until 8 PM EDT Monday for MEZ029-030.
MARINE...Small Craft Advisory until 8 PM EDT Monday for ANZ050>052.

&&

$$


Near Term...MStrauser/Sinko
Short Term...AStrauser
Long Term...AStrauser
Aviation...MStrauser/Sinko/AStrauser
Marine...MStrauser/Sinko/AStrauser