382
FXUS61 KCAR 261104
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
704 AM EDT Wed Jun 26 2024

.SYNOPSIS...
A cold front will approach later today, then cross the area
Wednesday night and Thursday morning. High pressure then builds
in from the west through Friday, then slowly slides offshore
Friday night and Saturday. A cold front approaches Saturday
night, then crosses the area on Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
700 AM Update: Isolated showers have spread across the forecast
area this morning. As seen on current radar imagery and CAMs
guidance, several rounds of showers will cross the area later
today along a few weak boundaries ahead of the next incoming
cold front. No major adjustments needed to the previous
forecast with this update.

Previous Discussion:
Current satellite imagery shows the approaching low pressure
system, right now centered in the Quebec province, and gradually
shifting eastward towards northern New England. A warm front
continues to lift northwards, with our forecast area in the warm
sector which has kept early morning temperatures in the 60s. As
warm air advection continues into the day today, highs will lift
into the 80s once more. Isolated rain showers will span across
the region early this morning, followed by a brief dry sector.
Another round of scattered rain showers will return this
afternoon, likely staying in the northern half of the CWA and
closer to the center of the low. A few thunderstorms are
possible with some CAPE around 500 to 600 J/kg, but otherwise
downsloping off the Longfellows combined with the placement in
the right exit region of a strengthening upper level jet streak
will limit the thunderstorm threat.

For tonight, a cold front will gradually shift over the forecast
area and begin to stall, while a center of low pressure rides up
along this boundary through the forecast area. Recent model
trends have slowed the forward progression of this front
tonight, such that the low tracks along the coast versus being
out over the Gulf of Maine. This could put the area of heaviest
precipitation into the Interior Downeast region up into the
Central Highlands, instead of being confined to just along the
coast. Since this shift in low track settles on a track in
agreement with model guidance over the last day and a half,
there is higher confidence in this location for moderate to
heavy rainfall. Though there are no large hydro concerns for
river flooding, these rainfall rates could result in localized
ponding on roadways and minor flooding in any areas with poor
drainage. It is key to remember to always turn around, don`t
drown in any areas of flooding!

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Rain associated with a fast-moving shortwave will quickly exit
the area Thursday morning and some clearing is expected to
develop. The cold frontal boundary is expected to remain stalled
in the area by the time of max afternoon heating. Deep layer
shear will be in abundance as a strong jet moves over the area
in advance of an amplifying upper trough. The big question will
be how much SBCAPE can develop. Over 1000 J/kg should be enough
to generate storms with severe potential. That would be enough
to overcome a cap that is keeping afternoon convective activity
from showing up in most CAMS guidance. The ECMWF remains the
biggest proponent of afternoon convection in a corridor between
southern Piscataquis/Penobscot counties towards southern
Aroostook County...along the stalled front. While other
guidance hints at that corridor, models such as GFS/GEMS/NAM promote
a scenario with weaker convective activity in the evening
towards the North Woods and northern Aroostook. For now, have
hit most of the forecast area inland of the Downeast with a
slight chance of thunderstorms.

The cold upper trough crosses Thursday night with continued
shower activity in northern zones. Still might have an isolated
thunderstorm as mid level lapse rates steepen with the trough.
There is strong cold air advection Thursday night as 850mb temps
plummet towards 2 to 4C by early Friday morning. Expect Thursday
night lows to drop into the 40s to lower 50s. Would go into the
upper 30s for the North Woods if it clears out earlier than
currently expected. The cool air mass sets the area up for a
pleasant Friday with highs reaching the low 70s only due to a
very deep mixed layer. Humidity will be low with dew points in
the 40s. The cool air will be fairly short-lived as upper level
ridging quickly builds Friday afternoon and night. A shallow
radiation inversion will likely still yield comfortable lows in
the upper 40s to lower 50s Friday night.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Surface ridging moves rapidly offshore Saturday. A strong upper
flow seems likely to advect a lot of high clouds into the area
on Saturday ahead of a warm front. In spite of warming aloft,
increasing clouds will keep Saturday highs mostly in the lower
70s. The warm front will arrive later Saturday with rain that
will continue Saturday night. There are signs of another heavy
rain event Saturday night with PWs increasing towards 2 inches,
elevated instability above the frontal inversion, a strong low
level jet promoting powerful 850mb moisture transport, and a
deep warm cloud layer. Fortunately, this will be another
progressive event with rain moving out of the area. Models are
in decent agreement on a heavy rain event Saturday night.

The next concern will be potential for strong thunderstorms
Sunday afternoon. Once again, shear will be in ample supply and
a stalled frontal boundary is expected to be in place. Saturday
night rainfall will leave abundant low level moisture/high dew
points. An approaching upper trough will generate cooling aloft.
SBCAPE production remains in question...dependent in part on
high temps. GFS and ECMWF feature higher temps (upper 80s) than
we have forecast using NBM (lower 80s).

The remainder of the extended forecast calls for dry conditions
and temperatures trending below normal as cool Canadian high
pressure builds.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR conditions expected across all terminals through
the day today. Scattered rain showers moving in from the west
could briefly lead to MVFR cigs but should quickly clear as the
shower moves through. Rain shower chances continue through the
afternoon, though cigs will generally remain around VFR. SW
winds today will increase to 10 to 15 kts and gusts 20 to 25
kts. Tonight, winds become light and variable as more numerous
rain showers move in and cigs fall to IFR/LIFR in moderate to
heavy rainfall.

SHORT TERM:
Thursday...Chance of morning IFR cigs at BHB and coastal sites
with MVFR cigs during the morning inland. VFR in the afternoon
outside of isolated thunderstorms, most likely towards FVE and
Clayton Lake. Light west winds.

Thursday night through Saturday...VFR. Northwest winds on
Friday at 5 to 10 will become southerly on Saturday at 10 to 15
kt.

Saturday night into early Sunday morning...IFR cigs and tempo
IFR vis in rain. Isolated embedded thunderstorms. LLWS likely.
South winds 10 to 20 kt.

Sunday...Becoming VFR with a chance of afternoon thunderstorms.
Southwest winds 10 to 15 kt.

&&

.MARINE...
NEAR TERM: Winds and seas should remain below SCA criteria
today, though as a system approaches from the west, swell may
lead to seas approaching 5 ft on the outermost reaches of the
coastal waters. Gusts may briefly reach 25 kts, but will likely
remain below 20 kts through today and continue to diminish into
the night tonight.

SHORT TERM: Fog will be possible Thursday, but should move away
from the waters Thursday night. Fog returns Saturday night into
Sunday morning. An SCA is possible is spite of strong stability
for Saturday night into Sunday. Did reduce guidance winds due
to the inversion and expect model sea heights will tend to
decrease in future runs as the models catch on to the lower
winds.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.

&&

$$


Near Term...AStrauser
Short Term...MCW
Long Term...MCW
Aviation...AStrauser/MCW
Marine...AStrauser/MCW