843
FXUS61 KCAR 230119
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
919 PM EDT Wed May 22 2024

.SYNOPSIS...
A weather disturbance crosses northern Maine late tonight into
Thursday morning. A cold front crosses the area Thursday,
followed by another cold front on Friday. High pressure then
builds in for the weekend. Low pressure begins to approach from
the west Monday.

&&

.NEAR TERM /THROUGH THURSDAY/...
9:19 PM Update: The 00z Caribou sounding showed a couple of
caps. It remained dry today with no showers this afternoon or
evening across the FA. There is a disturbance moving out of
Quebec with showers and thunderstorms along and west of the
Saint Lawrence River Valley. The first of this activity may try
to work into the far western portion of the FA by around 06Z,
but upstream radars would indicate that the main activity which
is still well west of Quebec City would likely hold off until
closer to daybreak. The best chance of showers with possible
embedded isolated thunderstorms will be across our western and
northern zones very late tonight and into mid-late morning
Thursday. Made some adjustments to mainly the PoPs, and mostly
to slow the onset of showers across the northern and western
zones for the next several hours based mostly on the latest
radar trends. Otherwise, no significant changes are planned at
this time.

Previous discussion:
Tonight... Another mild night with lows in the mid 50s to low
60s, coolest near the coast. The upper level ridge axis moves
east of us overnight, and a very subtle shortwave trough/vort
max approaches from the SW. This should bring increased shower
activity late in the night mainly in the north. With elevated
instability can`t rule out an embedded lightning strike, but not
expecting anything strong. Went with likely PoPs in the north,
with rain totals in the north from 1/4 to 1/2 inch where the
showers do hit late tonight.

Thursday...
The above-mentioned shower/storm activity in the north should
move into New Brunswick by late morning. Then comes a couple
hour lull late morning to midday, before convection fires again
in the warm, muggy airmass. Convection Thursday afternoon will
have more to work with than recent days, with an approaching
upper trough and cold front as a forcing mechanism, and deeper
wind shear (mainly speed shear). SPC has all but the NW part of
the area under a marginal risk, and this seems reasonable. The
cold front will move through the North Woods by about midday,
then east through the rest of the area in the afternoon. All
thunderstorm potential will be just ahead of the cold front as a
broken line of showers and storms. Some question as to when
storms will fire, as this depends on the exact speed of the
front and the dissipation of morning low clouds and resulting
instability. Overall the best risk of stronger storms will be
over eastern portions of the area, with the safest bet being
from about Millinocket and Dover Foxcroft east to Southern
Aroostook and Northern Washington County, and added gusty
winds/small hail to this region. May need to expand the area of
enhanced wording, but don`t have enough confidence for areas
further north or south than this zone, as it`s possible areas
further north won`t have enough instability by the time the
front passes, and areas further south could be too impacted by
the marine layer. Although there won`t be much of a temperature
gradient with the cold front, we do dry out very rapidly behind
the cold front, with showers and storms ending from west to
east mid to late afternoon.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A few showers and a rumble of thunder or two will be possible at
the coast early Thursday evening as the aforementioned cold
front moves through. Otherwise, skies will clear from northwest
to southeast Thursday night as the front moves offshore. Colder
air will be lagging behind the front for the most part. However,
the air mass will be dry enough for lows to drop into the 50s.

Friday will feature a secondary cold front and associated upper
trough approach the area. This will bring in colder air aloft to
Central Highlands northward. Expecting enough instability for
showers to develop along with a few thunderstorms in this area.
Model soundings show freezing levels in the 6000-8000 feet
range. Thus, cannot rule out some small hail or graupel. The
Bangor region and Downeast will remain dry on Friday due to less
instability. Clouds and showers will keep northern areas in the
lower to mid 70s. More sunshine will allow the Bangor area and
Interior Downeast to see highs near 80 degrees. Cooler
temperatures at the coast once again.

Any showers or storms come to an end by Friday evening as the
cold front moves away. Behind the front, cooler air rushes into
the area, with 850mb temperatures 0C to 3C. That said, expecting
west to northwest winds to be strong enough to prevent
decoupling. Forecasting lows in the 40s in the North, with lower
50s near Bangor and Downeast. If winds drop off more than
expected, some of the coldest spots in the North could drop into
the 30s. High pressure will bring a mostly sunny day on
Saturday. Highs will generally be in the 70s with dew points in
the 40s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Dry conditions continue through Saturday night with high
pressure beginning to move off. A shortwave could bring a shower
or two on Sunday. Thereafter, models agree on a low pressure
system tracking into the Great Lakes and into Canada from
Monday into midweek. Some timing differences between models,
with the ECMWF somewhat slower than other guidance. Based on
current guidance, chances of rain increase late Monday into
Monday night, continuing on and off through midweek. Potential
exists for significant rainfall as PWATS reach or exceed 1.50
inches for a time.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
NEAR TERM:
VFR late this evening. Likely remaining VFR through the night
for Downeast, including BGR/BHB. Can`t totally rule out some low
clouds from time to time especially BHB late tonight, but didn`t
have enough confidence to include in the 00z TAFs. For the
north, including areas from HUL N, reasonably high confidence in
a period of IFR ceilings with an area of showers from roughly
8-13z. Could be an embedded rumble of thunder, but didn`t put in
TAF because not enough confidence. Generally VFR areawide late
morning into the afternoon Thursday. However, a line of
showers/storms is likely in the early to mid afternoon,
progressing from W to E through the area. These storms could
bring briefly gusty winds and MVFR/IFR conditions before
conditions improve to VFR again after approximately 20z. Winds
generally light tonight, become S 5-10 kts Thursday morning,
switching to the SW late afternoon.


SHORT TERM:
Thursday night...Brief MVFR/IFR at coastal terminals early
evening with VCTS and BCFG. Otherwise VFR. Winds WSW 5-10kts.

Friday...Mainly VFR. Brief MVFR possible at Aroostook terminals
in the afternoon with SHRA and VCTS. Winds SW 5-15kts.

Friday night-Saturday Night...Mainly VFR. Winds WNW 5-15kts,
becoming light and variable Saturday night.

Sunday-Sunday Night...Mainly VFR. Brief MVFR possible in VCSH.
Winds SSE 5-10kts.

Monday...VFR lowering to MVFR with -SHRA possible late. Winds SE
5-10kts.

&&

.MARINE...
NEAR TERM: Conditions remaining below small craft levels, with
some patchy fog tonight into early Thursday.


SHORT TERM: Winds and seas remain below Small Craft Advisory
criteria from Thursday night through the weekend. Visibility
could be reduced early Thursday evening with fog before a cold
front moves through. A shower or thunderstorm is possible
Thursday evening with the frontal passage.

&&

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

&&

$$


Near Term...CB/Foisy
Short Term...Clark
Long Term...Clark
Aviation...CB/Foisy/Clark
Marine...CB/Foisy/Clark