NWS Gray, Maine Area Forecast Discussion



000
FXUS61 KGYX 161528
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1028 AM EST Sun Dec 16 2018

.SYNOPSIS...
As high pressure pulls away to the east today, low pressure will
emerge off the Mid Atlantic coast and track near Cape Cod
tonight. This will spread some snow across parts of the area,
with southern New Hampshire and the coastal plain of Maine
getting a few inches of accumulation. As the snow moves east on
Monday, a cold front will be moving in from the northwest.
Expect a stiff northwest wind starting late Monday with colder
weather arriving for Tuesday and Wednesday. Another storm system
will impact our area on Friday with more wintry weather
possible.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1025 AM Update...Have adjusted the forecast a bit based on
latest trends in observational data. Continuing to watch light
precip shield across MA moving northward. Have increased PoPs a
bit across southern NH for this afternoon based on radar trends.
However, with temperatures already above freezing, don`t foresee
much in the way of issues with rain - perhaps mixed with some
snow and sleet. A few pockets of light fzra possible higher
elevations of the Monadnocks where temps are colder. However,
not advisory for this at this time because of limited areal
coverage. Otherwise, continuing to peruse 12z model guidance for
heavier precip tonight. Still looks like a challenge with
varying thermal profiles. Will elaborate on this more with
afternoon package when the complete 12z model suite and some
ensemble info can be digested. However, advisories will likely
be needed for a portion of the forecast area.

ORIGINAL DISCUSSION...
High pressure slides east today with clouds increasing from the
southwest as low pressure emerges off the Mid Atlantic coast
this afternoon. As it gets closer, we may see precipitation
begin across southwest New Hampshire later in the afternoon. Dry
air in place ahead of the precipitation will likely slow its
progress across the area as well as allow room for evaporational
cooling to cool temperatures down enough for snow to be the
dominant precipitation type.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Low pressure moves east to the south of Cape Cod tonight with
precipitation spreading eastward along the coastal plain
overnight. As precipitation arrives expect evaporational cooling
to allow this to fall mainly as snow. Snow ratios are not that
great due to the relatively warm nature of this system
preventing the ideal alignment of moisture and lift within the
snow growth zone. This, along with temperatures near or slightly
above freezing may keep total accumulations down. Current
thinking is that 1 to 4 inches is likely in a strip from
southern New Hampshire along the coastal plain of Maine with
precipitation ending early Monday. It may stick around into
Monday afternoon on the Midcoast.

Meanwhile, a cold front will be arriving from the northwest and
will cross the region Monday evening. It will be accompanied by
some gusty northwest winds and mountain snow showers.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The upper level low slowly pulls to the east Monday night,
however not before some additional upslope snow showers
continue over the northwest facing higher terrain. It will turn
much colder with H8 temperatures falling to as low as -18C over
the north by morning.

A strong northwesterly gradient will continue on Tuesday with
mixing allowing wind gusts to 40 kt as the mixing layer
increases during the day. Upslope snow showers will begin to
abate as the upper level trough continues to shift east.

A large ridge of high pressure will bring dry conditions to the
region Wednesday and Thursday. There will be a moderating trend
as well as winds shift to the southwest with all areas reaching
the freezing mark by Thursday.

The 00Z guidance suite remains in relatively good agreement in
regards to the overall development and track of a cutoff low
pressure system later in the week.

A large, slow moving upper level low will enter the southeastern
United States Thursday night. A strong meridional flow will set
up across the region allowing warm air to pour in aloft as a
surface low pressure system moves along or just west of the
Appalachian spine. This will allow for mixed precipitation to
enter the region.

As the surface low passes west of New England late in the week,
the mixed precipitation may change to all rain as warm air
continues to advect into the region, initially aloft, but
eventually at the surface as well. There are indications that a
wave of low pressure may form along or near the eastern
seaboard. If this occurs, this feature may hold cold air in
longer across the interior, extending the length of time we
receive mixed precipitation.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Short Term...Conditions should stay VFR today (MVFR across
southern NH), with increasing clouds and lowering ceilings from
southwest to northeast beginning late today in southern New
Hampshire and through the night across the coastal plain of
Maine. IFR conditions are likely as snow falls in this area.
Should see improvement here to VFR on Monday, though some MVFR
conditions arrive in the mountains Monday evening along with a
northwest wind.

Long Term...Gusty northwesterly winds will enter the region on
Tuesday. This may initially start as LLWS Monday night before
daytime sun is able to mix the winds down to the surface. VFR
conditions remain through the end of the week when the next
widespread precipitation system brings a wintry mix and IFR.

&&

.MARINE...
Short Term...As low pressure tracks to our south, an easterly
wind will develop over the Gulf of Maine and gust to 30 KT or
so.

Long Term...Departing low pressure on Monday night into Tuesday
will bring gusts to Gale force to the waters. A gale watch
remains in effect for Monday night into Tuesday night.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Watch from late Monday night through late Tuesday night
     for ANZ150>154.
     Small Craft Advisory from 3 PM this afternoon to 5 PM EST
     Monday for ANZ150-152-154.

&&

$$

NEAR TERM UPDATE...Ekster
SHORT TERM...Kimble
LONG TERM...Cannon

NWS GYX Office Area Forecast Discussion