-- Discussion containing changed information from previous version are highlighted. --
176
FXUS61 KCAR 191309
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
909 AM EDT Thu Sep 19 2024

.SYNOPSIS...
A cold front will approach from Canada today and cross the area
this afternoon. High pressure will build down from Eastern
Canada Friday into the weekend as low pressure remains well off
the coast. High pressure will crest over the region on Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
909AM Update...Removed fog over the coast and waters due to
early clearing. Otherwise, the rest of the forecast looks good.

Previous discussion...
An upper level ridge of high pressure building over Hudson Bay
Canada will support high pressure over far Eastern Canada which
will push a cold front into our region this afternoon, first
across the north during the early afternoon then on south mid to
late afternoon. The front does not have much moisture in it,
but most models are indicating that some isolated showers may
accompany the front as it pushes through during late afternoon
into early evening. Otherwise, today will be partly cloudy
across the area, to perhaps mostly cloudy nearer to the coast
where high clouds will be straying north from the offshore
storm.

The cold front will push offshore tonight merging its energy
with the offshore storm which will add a little intensification
to the system. Otherwise, the offshore storm should remain off
the coast. A northeast breeze will set up behind the front
filtering in some cooler air across the area overnight. High
clouds from the offshore storm will keep the sky partly mostly
cloudy. Other than a stray shower from the front in the evening,
dry weather is expected overnight.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
The blocking pattern that has prevailed across the FA ovr the
past week will be undergoing some evolution, with the cntr of
the upper high retreating further N ovr Can msly across Nrn QB
and Labrador. This allows low pres both at the sfc and alf to
reside ovr the open Atlc between Cape Cod and S of NS prov Fri
thru Sat, with the most cldnss ovr the S hlf of the FA and sct
shwrs from the offshore rn shield perhaps ocnly reaching the
Downeast coast durg this tm frame with very lgt QPF amts.

By Sat Ngt, both the sfc and upper low will move further SE of
NS prov as sfc high pres from QB builds swrd, at least taking
any rn chcs swrd from the Downeast coast. Sky condition,
however, will remain uncertain, with NE llvl winds making it
uncertain how well the air below the subsidence invsn drys out,
meaning that there could be areas of thin SC cldnss. Temps will
slowly trend from abv normal closer to seasonal norms durg this
tm.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Outside of some patchy SC cldnss at tms, Sun and Mon look to be
fair and cooler, even a little below seasonal norms as sfc Can
high pres ridges swrd. Ordinarily, we would have to be
concerned about frost potential late Sun Ngt across Nrn vlys
with the sfc high directly ovr the FA after a cool prev day high
temps, but low enough sfc dwpts and clrg from SC cld cvr are
both uncertain, so we did not lower fcst lows ovr the N to much
attm and will wait until we get closer to dtrmn a better frost
potential.

Mon Ngt at this tm does not look as cool as the llvl core of the
air mass moderates and llvl winds begin to return from the S.
Tue also looks fair at this tm with blended long range models
bringing increasing cldnss later Tue Ngt into Wed as llvl winds
increase from the S to what could be the beginning of the
breakdown of the Ern Can-New Eng blocking pattern. For now,
blended long range guidance holds off on any PoPs abv slgt chc
lvl until at least Wed Ngt, with onset tmg ranging as early as
Wed durg the day by the 00z dtmnstc GFS to as late as Thu (if at
all) by the 00z dtmnstc ECMWF. Temps look to cont msly near
seasonal norms into the midweek.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
NEAR TERM: Ceilings will drop to MVFR for a few hours this
evening across the north following the cold frontal passage, and
down to MVFR or IFR after midnight Downeast as the cold front
pushes through. Otherwise, VFR conditions are expected today
and tonight. Winds will be light and variable today, becoming
northerly across the north this afternoon, then light
northeasterly throughout the area tonight.

SHORT TO LONG TERM: Fri - Sun Morn...all TAF sites MVFR - low
VFR clgs. Sct Shwrs possible at KBHB Fri thru Fri Ngt. Lgt to
mdt ENE to N winds, with strongest winds at KBHB Fri thru Fri
Ngt.

Sun Aftn - Mon...all TAF sites low VFR clgs to unlmtd VFR with
Lgt and vrbl winds.

&&

.MARINE...
NEAR TERM: Wind and seas should remain below SCA today, but will
increase to gusts up to 20 kt over the offshore waters late
tonight. Some light fog or mist may be over the waters due to
high dew points today. Vsby should improve tonight as drier air
pushes down from the north.

SHORT TO LONG TERM: SCA ENE wind gusts and accompanying seas are
likely beginning Fri Morn and contg possibly into Sun msly
across our outer waters as sfc low pres ovr the open Atlc E of
Cape Cod slowly organizes, remaining well S of the waters. By
later Sun into Sun Ngt, the pres grad ovr the outer waters
should weaken enough as the low moves somewhat away for winds
and seas to subside below SCA thresholds. Kept close to blended
wv model guidance for fcst wv hts with wvs having two
components; a short fetch pd of 2 - 4 sec and an open swell
pd of 9 - 11 sec.

&&

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

&&

$$


Near Term...Bloomer/LaFlash
Short Term...VJN
Long Term...VJN
Aviation...Bloomer/LaFlash/VJN
Marine...Bloomer/LaFlash/VJN