Lebanon, New Hampshire 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

848
FXUS61 KGYX 220329
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1029 PM EST Sat Dec 21 2024

.SYNOPSIS...
An Arctic airmass will persist through this weekend with well
below average temperatures and potentially dangerous windchills.
After a dry Monday, light snow arrive Monday nights and Tuesday
with a passing clipper system. High pressure will then rebuild
over the region Wednesday through the end of the week with a
gradual moderating trend.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1020 PM Update...Have updated the forecast mainly for minor
items. Clearing continues to occur downwind of the mountains a
little faster than forecast so adjusted cloud cover a bit.
Otherwise, we remain on track.

615 PM Update...Little change to the going forecast other than
to extended PoPs a little longer this across central and
Midcoast ME as light, small-flake snow looks to continue for a
little longer. Otherwise, cold and windy.

Previously...

Upslope conditions will continue in the northern mountains
tonight. Will introduce at least chance pops for scattered snow
showers in the mountains overnight as the northwesterly gradient
remains in place. This wind flow will combine with an Arctic
airmass to produce very low wind chill values tonight. Air
temperatures in our well mixed layer will fall to the single
digits below zero in the north to the single digits above zero
in the south by morning. Wind chill values will be below zero in
all locations, approaching -20F across the higher terrain in the
north.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Breezy and continued very cold conditions will continue on
Sunday as high pressure over the eastern Great Lakes moves
towards New England. Most areas will remain in the teens for
afternoon highs.

As the large surface ridge crests over the forecast area Sunday
night, clear skies and light winds will be in place. Low surface
dew points will only add to the effects of radiational cooling.
By morning, some northern areas will fall to around 10 below
zero with single digits in the south. It will remain dry as we
head into the long range portion of the forecast.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Update...01z NBM guidance is in reasonable agreement with other
latest guidance in a light snow event for Monday night into
early Tuesday. Forecast has this well in hand as a 1 to 3 inch
snow event so no significant changes have been made.

Previously...

Overview...

The trough bringing the cold conditions moves east through
midweek as a ridge builds across eastern North America. A weak
shortwave crosses northern New England, likely bringing a light
snowfall for Christmas Eve to most of the area.

Details...

Cold conditions continue on Monday as the trough slowly moves
off to the east. Highs in the teens and 20s are expected again.
The day starts off sunny, but high thin cirrus clouds begin to
arrive by the afternoon hours ahead of an approaching system.
Clouds continue to thicken Monday night, keeping temperatures
above the previous couple of night`s readings.

A weak low pressure center associated with a passing shortwave
moves through during the day on Tuesday, spreading light snow
across most of the area. For those that missed out on last
night`s snow, this system brings the best chance for a white
Christmas. At this point snowfall amounts look light, with a
broad and general 1-4 inches across most of the area. The track
of the low will be important, with less forcing and less
snowfall south of the track. There is also the chance for some
slightly higher amounts through the higher terrain, and toward
the MidCoast. Across the higher terrain and north of the track,
high snow to liquid ratios should help to support slightly
higher snowfall amounts, but exactly where remains in question.
Towards the MidCoast, more moisture is likely drawn in off the
ocean as the low begins to slowly strengthen, also helping to
increase the chance of slightly higher totals here. Parts of
southern Maine and southern New Hampshire are likely to be on
the lower end for this event, with the bulk of the forcing
missing to the north, so this area remains the most in question
as to whether or not enough snow will fall to stick around until
Christmas morning, but it still looks like a decent chance at
this point.

The low moves eastward Tuesday night, with some light snow
showers possibly lingering across eastern areas into Christmas
Day, but will be higher dependent on the strength of a lingering
weak inverted trough. Temperatures continue their gradual
warming trend, with highs along the coast starting to warm above
freezing, and mid 20s across the north.

The highly amplified ridge builds across central and eastern
North America through the end of the week, bringing a slow
moderating trend. Temperatures don`t actually rise all that much
considering how amplified the ridge is, and with it spreading
above freezing air across Hudson Bay. Instead, high pressure at
the surface remains centered across and just north of New
England, helping to filter in some relatively cooler air in an
otherwise very warm pattern. So while it`s not a snow lover`s
dream, it`s not a nightmare either. Highs warm to near 40 along
the coast by the end of the week, with mid 30s across the
interior. And with high pressure in place, lows continue to drop
into the teens and 20s each night.

&&

.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
Short Term...Scattered snow showers will persist into this
evening allow for MVFR conditions in the north. Otherwise,
expect VFR conditions for the short range portion of the
forecast. Winds will be gusty tonight into Sunday. No LLWS is
anticipated.


Long Term...VFR conditions continue through Monday night. Light
snow brings restrictions on Tuesday with MVFR to IFR conditions
likely. VFR conditions then return by Wednesday, and likely
continue through the remainder of the week.

&&

.MARINE...
Short Term...Gusty winds continue tonight and Sunday out of the
northwest. SCAs will remain in place. Winds and seas will then
gradually diminish late Sunday and Sunday night. Freezing spray
is possible tonight into early Sunday.

Long Term...Fair conditions prevail through Monday night. A
weak low pressure system crosses the waters on Tuesday with
snow, but conditions remain below SCA levels. Fair conditions
return and continue from Wednesday through the end of the week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 4 PM EST Sunday for ANZ150>154.

&&

$$


NEAR TERM...Cannon/Ekster
SHORT TERM...Cannon
LONG TERM...Clair/Ekster