190
FXUS61 KGYX 250905
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
405 AM EST Mon Nov 25 2024

.SYNOPSIS...
Weak high pressure crosses the area today. Low pressure crosses
the region Tuesday bringing a light wintry mix to start across
the interior Tuesday morning with rain becoming the dominant
precipitation type south of the mountains. Dry conditions are
expected Wednesday into Thursday morning. A more significant
low pressure system takes aim at the Northeast late Thursday
through Friday while there is uncertainty in to the track and
ultimate impacts.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Latest RAP13 pressure analysis early this Monday morning shows
vertically stacked low pressure over the Canadian Maritimes with
high pressure over the Great Lakes region. Satellite imagery
shows mainly clear skies over south-central NH and southwestern
ME while northwestern ME is mainly cloudy with upslope flow
continuing. Area webcams indicate that some light snow/flurries
continue to fall over the far north and mountains and this will
persist through this morning before diminishing by this
afternoon. Current temperatures are primarily into to 20s and
30s and some additional cooling can be expected. Gusty west-
northwesterly winds will make it feel colder though.

Surface high pressure will build over New England today as low
pressure departs well to our northeast. This will allow for a
partly to mostly sunny day south of the mountains with mainly
cloudy conditions persisting across the far north and the
mountains themselves. High temperatures will range from the
upper 30s to near 50 degrees from north to south (warmest in
southern NH). Northwesterly winds will become more westerly in
nature this afternoon while gradually diminishing as the PGF
weakens. Despite this, still expecting gusts up to around 25 mph
or so through much of the day.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
High pressure will drift to our east tonight ahead of an area of
low pressure that will be moving over the Great Lakes. Initially
skies will be mostly clear early this evening before clouds
increase in association with an approaching warm front and WAA
aloft. Forecast guidance continues to indicate that a weak
coastal low will then develop along this front Tuesday morning
before crossing over the Gulf of Maine during the afternoon.
This will result in a period of stratiform precipitation over
the region beginning early Tuesday morning over NH and western
ME before spreading east towards the Penobscot River Valley by
late morning.

Temperatures tonight will fall into the upper 20s to lower 30s
across the region and this combined with a developing warm nose
aloft will introduce a threat for light mixed wintry
precipitation including freezing rain and sleet for a few hours
over the interior and north on Tuesday morning. Generally
between a trace to a few hundredths of an inch of freezing rain
is expected with some of the higher terrain possibly getting
closer to a tenth or two of an inch. Despite these low amounts,
it does not take a lot of ice to cause travel issues. Given that
this is the first event of the season and the timing looks to
coincide with the morning rush, in collaboration with WFO
Burlington and Albany went ahead and issued a Winter Weather
Advisory where confidence is greatest for a period of light
freezing rain on Tuesday morning. Further to the south and along
the coast, temperatures are expected to warm to above freezing
before precipitation begins and therefore just a plain cold rain
is forecast. By the early afternoon all areas should be warm
enough for just plain rain outside of the mountains. Rainfall of
up to 1/2" is likely for most areas. High temperatures will
range from the upper 30s across the interior with the lingering
CAD to the upper 40s along the coast.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Long Term Update... The main focus in the long term continues
to be on the Thursday-Friday storm system, with the potential
for impactful winter conditions across at the least the
interior. The evening model runs have offered little new
clarity, with the GFS still mostly out to sea, while the Euro
and its ensembles remain consistent on a deeper low closer to
the coast. One model that did shift a bit was the Euro AIFS,
coming a little closer toward the Euro ENS solution, after
being more closely aligned with the GFS in earlier runs. POPs
have been increased slightly through this time, but uncertainty
remains on Precip type and placement.

Full Discussion...

Overview:
Low pressure will exit by Wednesday morning with mostly dry
weather Wednesday into Thursday morning. A more robust low
pressure system will track near the Northeast late Thursday
through Friday. Large variance in model solutions continue with
respect to the track and strength of this system, as well as the
resultant p-types. Colder air moves in behind this system over
the weekend with below normal temperatures favored into the
first week of December.

Impacts:
*A robust low pressure system tracking near the Northeast Thursday
into Friday will have the potential to bring wintry precipitation
and travel impacts. Finer details of timing and p-types will likely
take several more model cycles to come into focus.

Details:
Low pressure exits Tuesday night for a drying trend into
Wednesday morning. Fair weather looks to prevail Wednesday with
highs ranging from the mid 30s north to upper 40s south. Dry
conditions likely continue Wednesday night into the first part
of Thursday. Attention then turns to what is now a trough of low
pressure off the Pacific Northwest that will cross the CONUS
the next few days that could spawn a robust low pressure system
near coastal New England.

Large variance continues in the 12Z model suite with respect to a
potential impactful system Thursday into Friday. A somewhat more
consistent signal is apparent in ensembles with a low pressure
system taking a favorable track south of the area to bring
widespread wintry precipitation away from the coast. The ECMWF and
its ensembles have remained the most consistent with the track of
this system while the GFS has had several runs with this system
being a miss to the south.

A review of ensemble low tracks and 00Z cluster analysis reveals three
emerging camps for the system late Thursday into Friday. The first
cluster representing 34 percent of ensemble members (mainly EPS followed
by GEPS) favors a low track from the Ohio Valley across southern New
England and into the Gulf of Maine. This scenario would favor precipitation
starting as snow/wintry mix across much of the area with a change
to rain south of the mountains while the mountains and far north
stay mostly snow. The second cluster representing 25 percent of ensemble
members (mainly GEPS followed by equal weight of EPS/GEFS) favors
better phasing and a more amplified system. This scenario favors more
QPF and more warm air being drawn into the system off the Atlantic.
This would lead to less wintry precipitation south of the mountains
with even the mountains and far north potentially seeing snow change
to a wintry mix/rain. The third cluster representing 22 percent of
the members (mostly GEFS) does not phase resulting in weaker low
pressure system or waves of low pressure passing south of New
England. This scenario could result in a miss south or bring
chances for light snow to much of the area with snow mixing with
rain near the coast and less QPF. The primary feature associated
with this system is still offshore of the Pacific NW with a
secondary feature in the Arctic Circle near Alaska. This will
likely lead to continued run to run and model to model variance
with this system for the next few model cycles. Stay tuned, as
there continues to be the chance for a winter system impacting
the region Thursday into Friday.

Colder air moves in behind this system over the weekend with broad
troughing settling over the eastern CONUS. This will likely bring a
sustained period of winter-like conditions into the first week of
December.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
Short Term...VFR conditions will prevail through early Tuesday
morning except at KHIE where MVFR CIGs will persist through
today. Winds will be from the west-northwest with gusts up to 25
kts. Ceilings lower on Tuesday morning as RA overspreads the
region, bringing IFR to LIFR restrictions. A period of -FZRAPL
is possible at KLEB, KHIE, and KAUG from roughly 09Z through
15Z Tuesday. Winds will generally be light and variable. RA ends
Tuesday night with improving conditions. No LLWS is expected.

Long Term...Conditions improve Tuesday night with VFR likely
Wednesday into Thursday morning. A more robust system is
forecast to track near New England late Thursday and Friday.
Depending on the track, widespread wintry precipitation will be
possible along with IFR to LIFR conditions.

&&

.MARINE...
Short Term...West to northwesterly winds will gradually diminish
below thresholds hazardous to small crafts today into tonight as
high pressure crosses. Another period of SCA conditions is then
possible on Tuesday as weak low pressure moves over the waters.

Long Term... Winds shift out of the west Tuesday night with SCA
conditions likely through Wednesday morning. Winds and seas
drop below SCA thresholds Wednesday night into Thursday before
another low pressure system tracks near coastal New England late
Thursday into Friday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory from 1 AM to 1 PM EST Tuesday for
     MEZ007>009-012-013-033.
NH...Winter Weather Advisory from 1 AM to 1 PM EST Tuesday for
     NHZ001>009.
MARINE...Gale Warning until 7 AM EST this morning for ANZ150.
     Small Craft Advisory until 1 PM EST this afternoon for ANZ151-
     152-154.
     Small Craft Advisory until 7 AM EST this morning for ANZ153.

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Tubbs
LONG TERM...Clair/Schroeter