Area Forecast Discussion
Issued by NWS Portland, ME
FXUS61 KGYX 180036
Area Forecast Discussion
National Weather Service Gray ME
836 PM EDT Fri Mar 17 2017
High pressure with a dry but cold air mass will become centered
over northern New England tonight and Saturday and then drift
to the northeast Saturday night as low pressure develops south
of New England. This low pressure system will pass out to sea
southeast of Cape Cod Saturday night and then into the Gulf of
Maine Sunday. Across southern New Hampshire and southern and
central Maine there is a chance for some light snow late
Saturday night and Sunday as the system exits well offshore.
Warmer and dry weather is in store for Monday. A cold front will
cross the region Monday night followed by a secondary cold
front Tuesday night.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Have updated the grids based on current conditions and latest
guidance. Mostly clear skies reign over most of the forecast
area except for the far northeastern portions of the county
warning area. Dew points continue to run in the single numbers
to mid teens. With mainly clear skies and winds finally becoming
light, expect radiational cooling overnight. Have dropped min
temperatures by 5 to 10 degrees in all areas as even the
coastline fell into the single numbers last night. Don`t expect
as cold as last night, but have trended in the colder solution
below MOS Guidance. Would be greater radiational cooling if the
snowpack was fresh.
Have added freezing spray for tonight into Saturday over the
Otherwise, just minor modifications to the dew point, wind and
sky cover forecast for this evening.
Canadian high pressure becomes centered over Maine and New
Hampshire tonight so clear skies and calm winds are expected.
this will allow temps to radiate and become very cold once
again. Overnight lows will once again range from 5 below to 5
above zero in the mountains and foothills with readings dropping
to the teens to near 20 along the coast.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
High pressure remains over the area so a sunny day expected with
a cold start to the day. Temperatures will recover nicely and
reach into the upper 20s to mid 30s. Winds will remain very
Saturday night all eyes will be watching the rapidly developing
low off the southern New England coast. Models over the last
few days were trending to a further southern route leaving us
dry. Latest model runs are suggesting a track a little further
to the north. This will mean clouds overspreading the area from
south to north with some light snow or flurries over southern
areas late Saturday night. Using a blend of model pops. Another
cold night Saturday night as the offshore storm drags cold air
from the north southward into the area.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
500 MB pattern over the CONUS will continue to be somewhat
changeable, and not lock into a true +PNA pattern, but will
trend toward troughing over the ern CONUS with farily strong
blocking downs tream over the ern Atlantic. Although we will
some warmer ridges, the troughs will continue to tap into the
coldest air near Hudson Bay and will not allow for any extended
warming. Overall, temps will run below normal, although
Monday/Tuesday will see temps near to slightly above normal.
Biggest challenge in the extended will be Sunday as 12Z GFS/NAM
deepen develop low outside the 40/70- benchmark and tend to lift
it northward across the Gulf of ME on Sunday as 500 mb low
closes off over srn New England. This is a somewhat significant
change from previous model runs, and would bring some light snow
accumulating to coastal areas on Sunday, which could mix with a
little rain close to the coast. To complicate matters, the 12Z
Euro is experiencing technical difficulties and is indefinitely
delayed. The 12Z CMC deepens the system like the American
models, but, keeps it further offshore, which may bring some
accumulating snow to SE NH and coastal York county. With this in
mid have increased pops on Sunday and left them at chc for now,
with possible accums of an inch or two for the most part during
the day Sunday, However should models trend for a deeper low
and/or a track closer to the coast, amounts could increase in
Sunday night may see some lingering snow in the mid-coast, but
all areas are expected to clear out overnight. Weak ridging
builds in Monday and Monday night, with a cold front
approaching from the west on Tuesday. Temps should warm to
around normal on Monday, generally mid 30s to mid 40s from N to
south and partly sunny skies. Tuesday should warm up even
further ahead of the cold front with temps in the 40s, and may
reach 50 in the warm spots of srn NH and SW ME.
The cold front should come through mostly dry, with the
exception off SHSN in the mtns late Tue and Tue night, with
highs dropping to the 20s to around 30 Wed and Thu.
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Short Term...VFR conditions through Saturday night.
Long Term...Flight restrictions possible in -SN, especially
coastal terminals and KMHT on Sunday. Otherwise VFR.
Short Term...Have added freezing spray to the forecast for
tonight into Saturday over the coastal waters.
Winds and seas will remain light through Saturday
evening. Late Saturday night northeast winds and seas will
begin to increase in response to developing low pressure south
of New England but will remain below SCA conditions.
Long Term...Gales are possible Sunday into Sunday evening, with
a period of SCA following into Monday. SCAs are likely again
behind a cold front Tue night and Wed.