NWS Forecast Discussion

For Fremont, NH

FXUS61 KGYX 300229 AAA

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
929 PM EST Sun Jan 29 2023

This week will be seasonably cool with occasional snow showers,
mostly over the mountains. Exceptions will be light rain and
snow through this evening... and another round of light snow
late in the day Monday, which will impact areas outside of the
mountains. The coldest air of the season is likely to arrive
late this week with temperatures potentially dropping well below
zero Fahrenheit.


9:30 PM Update...Forecast is in good shape, just a few
lingering flurries across Coos County and the Western Maine
Mountains through midnight tonight. No significant updates to
the remainder of the forecast except for trending cloud cover
down along Southern New Hampshire and coastal areas.

6:30 PM Update...Quick update this evening to drop the Winter
Weather Advisory a few hours early across Central Somerset
County. Current webcams and observations are showing
visibilities above 5 miles with flurries expected to continue
through a few more hours, but accumulating snow has mostly
ended. Remainder of forecast is in good shape with the cold
front beginning to push into the International Border Area of
the Western Maine Mountains. A quick shot of cooler air will
mover into the region through the overnight hours.

Broad, weak low pressure is located around or just to the east
Lake Erie per latest surface analysis, and this low will track
roughly along or just south of the International Border through
this evening and toward the Canadian Maritimes overnight. Light
snow has broken out over the area with moistening and lift out
ahead of this low, mainly across northern areas so far, but
there have been reports of light snow as far south at IZG and
AUG recently. To the south of these areas, temperatures have
warmed up quite nicely with a warm front lifting through the
area, and while coverage of precip is expected to be much less
for southern areas, anything that does fall should be mostly
light rain at this point. Toward the foothills, ptype should
continue to be snow for a few more hours, but there could be a
mix of rain/snow toward early this evening as the warmer air
slowly advances northward. Across the north, temperature
profiles are expected to remain subfreezing keeping precip type
as all snow, with a few inches of snow still possible through
this evening, especially across the far north. The Winter Wx
Advisory continues for central Somerset county through this
evening where the higher accums are expected, generally 2-4",
possibly up to 5".

While the low lifts to the north and east early this evening,
some drier air will push into the region from the south and
west, gradually ending precip for central and southern areas
while it hangs on a little longer across the north.
Temperatures will actually be fairly mild through this evening
and tonight, but the low pressure will eventually drag a cold
front through, and cold air advection will drop temperatures
back into the teens across the north and generally the 20s to
the south, except lower 30s across southern NH.


Monday starts off dry, but another in our series of weak systems
will approach and cross through later in the day, bringing another
round of light precip to the region from late afternoon into the
evening hours. Models are in good agreement on the track of the weak
low, roughly across north MA or southern NH and into the Gulf of
Maine, which will give most the area snow as precip type. The
exception may be across southern NH and far SW ME early Monday
evening where temperature profiles are expected to be warm enough to
start as rain before switching over to a brief period of light snow.
Hi-res guidance along with the globals and their ensembles members
remain consistent in this being a light event ranging from a few
hundredths to around a tenth of an inch of QPF, which will generally
translate to an inch or two of snow accum from the foothills to
northern areas and less than an inch to the south.

Once the low passes far enough east, northwest winds on its backside
will carry in some drier air, which will end the light snow from
west to east from late evening into the early overnight hours along
with a partial clearing of skies south of the mountains. As per
usual though, scattered upslope snow showers are expected to
continue in the mountains. Overnight lows are forecast to be in the
teens to lower twenties south of the mountains and single digits to
teens to the north.


While the weather pattern will be fairly quiet for mid-winter,
the primary story for the extended forecast period will be a
plunge of Arctic air into New England by this weekend. After a
cool, zonal flow regime through mid-week... medium range
ensembles heading through the end of the week show departures of
multiple standard deviations below average in temperature
fields. While there is still some wiggle room WRT how
significant the event will eventually be... dangerously cold
temperatures and wind chills can be expected at least across the
mountains by this weekend.

Starting off Tuesday... breezy westerly flow and a mix of sun
and clouds prevail with upslope snow showers early on mostly
over the mountains as low pressure departs to the east.
Temperatures will be noticeably cooler behind this wave, with
highs generally in the teens and 20s. Surface high pressure
building into New England eventually allows winds to relax
overnight with a cold night on tap. Since clouds are still
forecast to be around in fast zonal flow... won`t go all-in on
coolest projections at this point... but low temperatures in the
single digits either side of 0F (perhaps low-teens along
southern and coastal peripherals) according to the operational
blend could potentially lower by another 5-10 degrees should the
sky/wind forecast trend more favorably. Daytime Wednesday will
continue the theme with highs again in the teens and 20s under
a mix of sun and clouds.

Mountain snow shower chances return with a wave passing well to
our north late Wednesday into early Thursday, offering little
for the lower elevations as forcing and sufficient moisture
depth appears to be limited to the upslopes. Temperatures
rebound toward normal on Thursday with flow turning
southwesterly ahead of the next wave of low pressure approaching
from Canada. This largely moisture- starved wave will offer
another round of low-end PoPs from light snow showers, again
mostly in the mountains... but what follows is more significant.

Model consensus continues to point to a significant intrusion
of Arctic air over New England early Friday into Saturday. This
will likely be the coldest airmass that has descended over the
region thus far this season, with t850 of -20C a near-guarantee
for northern areas by Friday evening. There is increasing
confidence in this significant plunge of cool air as ensemble
averages continue to trend cooler and with less variance both at
the surface and aloft. Generally speaking, while the GEFS has
more variance/less confidence versus the ENS... there is still
a > 50% chance of temperatures AOB 0 deg F Friday night across
the entire area with the GEFS, versus a near- guarantee from the
ENS. With this airmass overhead, temperatures as low as the
negative-20s will be possible during the coldest period...
Friday night into Saturday... across the north with negatives
present to the south. For high temperatures, Friday will be
cooler than Thursday... but Saturday is likely to be the coldest
day with highs for now forecast in the single digits on either
side of 0F. On top of all of this... brisk northwest winds will
make these temperatures feel even colder, with wind chill
headlines of some kind likely to result.

Let`s end this discussion on warm note with a rebound back toward
average temperatures on Sunday, which has as strong of model
consensus as the preceding Arctic airmass. This comes as the
progressive and amplified pattern brings a stout ridge of high
pressure across the CONUS to our doorstep with an increasing SWerly
flow through the column.


Short Term...The majority of flight restrictions the rest of today
into tonight are expected to be from LEB to AUG and points northward
as a result of low ceilings and reduced visibility from light snow.
In general, these are expected to be MVFR but could drop to IFR at
times. Low-end VFR ceilings are expected elsewhere, but there could
be a few MVFR ceilings tonight as a weak cold front crosses through
northern New England. VFR conditions expected through Monday
afternoon, but then ceilings will lower to MVFR in the afternoon and
evening as a low pressure brings more light snow (or rain/snow mix
for MHT/PSM). Conditions will improve through Monday night as the
low exit to the east, but upslope snow showers and MVFR ceilings
will probably continue at HIE and perhaps LEB.

Long Term...VFR prevails except for occasional MVFR CIGs in the
mountains (mostly KHIE) through the end of the week. Winds will
have a general westerly clip, varying between NWerly and SWerly
from day- to-day. Wind gusts are forecast to be highest Friday
and Saturday when a bitterly cold air mass descends on the
region, with northwesterly gusts potentially exceeding 25-30 kts.


Short Term...Gusts to or in excess of Gale Force across the eastern
waters will continue into this evening, perhaps a few across
Penobscot Bay as well, while SCA conditions continue elsewhere.
Conditions then improve overnight as winds diminish as they veer to
the northwest and then north behind a cold front that will cross
through. Conditions will continue to improve through Monday, but
then another weak low pressure will move across the waters late
Monday into Monday night bringing another increase in winds and seas
across the waters. However, these look just shy of SCA levels at
this point.

Long Term...This week will feature a general westerly flow
over the Gulf of Maine, turning more SWerly or NWerly on a day-
by-day basis. Highest confidence in 25+ kt winds developing
come in the wake of a cold front Thursday night with potential
for gale force winds developing behind a reinforcing cold front
late Friday.


MARINE...Gale Warning until midnight EST tonight for ANZ150-152.
     Small Craft Advisory until 4 AM EST Monday for ANZ151-153-154.


NEAR TERM...Combs/Dumont

NWS GYX Office Area Forecast Discussion