Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 210832
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
332 AM EST Sun Jan 21 2018

.SYNOPSIS...
A weak cold front will drop south across northern New England
today and stall over southern New England tonight. Low pressure
moving through the Great Lakes will spread some light snow
across the region late Monday into Monday night, with the
stalled front lifting northward as a warm front. Low pressure
tracks east along this front on Tuesday with snow changing to
sleet and freezing rain before temperatures warm. As the low
moves east it will pull a cold front through the region Tuesday
night with colder weather arriving for the next few days.

&&

.NEAR TERM /TODAY/...
Clouds will continue to streak across the forecast area in the
proximity of a weak, stalled out front. High clouds will persist
in the south with low cloudiness over central and northern
areas. Early morning fog in the Keene area is expected to
dissipate after sunrise.

Expect 30s in northern areas today, with lower to mid 40s in the
south allowing for more melting. The gradient will relax towards
the afternoon hours.

&&

.SHORT TERM /TONIGHT AND MONDAY/...
Clouds will increase and thicken tonight as a warm air
advection pattern develops after midnight and the front begins
to move north.

This warm front will likely stall near the Massachusetts and
New Hampshire state lines tonight and Monday. This will allow a
nose of colder, drier air to filter into the region as high
pressure remains entrenched over southeast Canada.

Wet bulbing effect will likely allow the precipitation type to
begin as all snow even over southern areas. However, significant
warming aloft will occur by late Monday allowing for some rain
and snow mix over far southern New Hampshire as the
precipitation will remain light. This mix will occur as boundary
layer temperatures warm into the 30s late in the day as a broad
area of low pressure heads towards the Great Lakes. A wave of
low pressure will likely form along the Maine coast however as
we head into the long term portion of the forecast.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Surface warm front tries to lift northward Monday night, but
cold air damming at the surface will likely hold tough and force
this warm front aloft. Light snow ahead of the warm front moves
across the area with generally 1 to 3 inches expected.
Temperatures aloft warm above freezing after the warm front
passes, though any precipitation behind the warm front will
likely be in the form of light drizzle or freezing drizzle. Next
round of precipitation arrives on Tuesday as the complex low
pressure system arrives from the west. Steadier precipitation
picks up again, this time with a highly inverted low level
temperature profile supporting widespread freezing rain to the
north of the surface warm/coastal front. Models still are having
a tough time resolving this low level cold wedge of air, though
the CMC and NAM have done the best job showing the cold surface
temperatures hanging on through midday Tuesday in interior
western Maine. Have based the temperature and wind forecast off
of a blend of these two models with some manual adjustments.
Although we do expect much of the area to see some freezing
rain, the impact will likely be less than normal considering the
coating of snow expected beforehand. South of the warm/coastal
front temperatures will warm into the 40s to low 50s ending the
freezing rain threat. Cannot rule out a rumble of thunder
considering moist adiabatic mid level temperature profile.

Cold/Occluded front pushes through the area Tuesday afternoon
and evening, ending the steadier precipitation. With winds
shifting to the west behind the front, any remaining cold air
damming will break allowing the dammed areas to warm up a bit
before colder temperatures arrive by Wednesday morning. Some
lingering snow showers are possible through the day Wednesday as
the upper low moves by. Colder temperatures expected Thursday
and Friday, though not all that cold by mid winter standards or
even this winter standards. Surface high pressure shifts across
the area Friday night allowing a southerly flow to bring a warm
up for next weekend.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
Short Term...VFR conditions today with areas of MVFR ceilings
in the mountains. Areas of MVFR ceilings develop later tonight
into Monday as onshore flow sets up.

Long Term...Expect IFR conditions with light snow moving across
the area Monday night. Snow changes to sleet and freezing rain
on Tuesday across interior portions, while southern, western,
and coastal sections will warm above freezing earlier in the day
Tuesday. Expect low level wind sheer in the cold air dammed
areas of interior western Maine and eastern New Hampshire. Cold
front moves through Tuesday evening bringing the steadier
precipitation to an end and a gradual improvement to VFR by
Wednesday. Lower ceilings may linger in the mountains right
through the day Wednesday into Wednesday night before
dispersing.

&&

.MARINE...
Short Term...Gradient continues to relax. Have dropped SCAs for
the early morning hours. A few gusts near 25 kt are possible
well off the Midcoast region early, but these will be
diminishing as well.

Long Term...Warm front lifts north across the Gulf of Maine
Monday into Monday night. Low pressure moving east along the
front will allow southerly winds to increase to gale force ahead
of it. There is a low probability that some storm force gusts
could occur. The low will drag a cold front across the Gulf of
Maine late Tuesday, with winds behind the front possibly
reaching gale force again on Wednesday.

&&

.HYDROLOGY...
Many rivers remain frozen and/or affected by ice jams. With
additional liquid precipitation expected over much of the area
on Tuesday, it is possible that there could be more ice movement
and some minor flooding into Wednesday.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 6 AM EST early this morning for
     ANZ150-152-154.

&&

$$

NEAR TERM...Cannon
SHORT TERM...Cannon
LONG TERM...Kimble



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