NWS Forecast Area Discussion - New England Area

000
FXUS61 KBOX 172105
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
405 PM EST Sun Dec 17 2017

.SYNOPSIS...
A weak wave of low pressure may bring spotty light snow to the
region late tonight into Monday morning, mixed with rain along
the south coast. Temperatures will be milder on Tuesday ahead
of a cold front, then turn blustery and colder Wednesday into
Thursday but with dry weather prevailing. Low pressure will
likely pass to our west Friday night and Saturday, probably
bringing mainly rain and a period of rather mild temperatures
along with some wind. A period of unsettled weather may return
sometime Christmas Eve into Christmas, but timing and
precipitation types are uncertain.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...

400 PM Update...

High pressure to the north of the region will keep the region dry
this afternoon. Frontal system to our south combined with
increasing mid-level moisture as increased cloud cover across the
region. Have updated the forecast to account for this. Otherwise the
forecast remains on track for the rest of the day.

Tonight into Monday morning...

***Light snow showers could impact the morning commute***

Dry weather to start the night as overnight lows fall into the teens
to low 20s. Not quite as cold as last night thanks cloud cover which
will limit radiational cooling.

Increasing potential for snow showers to develop during the
overnight hours and move through southern New England during the
morning commute. Low pressure over the Great Lakes will slowly begin
to move towards the Northeast pushing the frontal system to our
south northward as a warm front. Ahead of the front, isentropic lift
within the WAA pattern will help provide just enough lift for precip
to occur. Increasing moisture in the mid-levels will help saturate
the snow growth region and with soundings keeping the profile below
0C anticipate snow showers. The lift does appear weak thus continued
the mention of light snow showers late tonight and into the morning
hours.

One thing we will have to watch is the warm layer at 950mb. Both the
EC and HRRR are in agreement of thermals which keeps this warm layer
just south and west of our area, although it is close. Do not plan
on issuing any winter weather advisories at this time for CT or RI.
However with the cold temperatures overnight, any snow showers that
do occur will accumulate on the roadways just in time for the
morning commute. Will issue an SPS to highlight this concern for
tomorrow morning. Anyone traveling should take it slow as roads can
become slick. Overall snow accumulations will be around a coating to
less than an inch.

Snow should end by the mid-morning hours as the better lift moves
northward.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...

Monday afternoon into Monday night...

***Low chance for spotty freezing rain across Northeast
 Massachusetts late Mon Afternoon***

Warm front to the south will begin to push into southern New England
during the day on Monday. Despite southerly winds at the surface, 2m
Temps from Hi-res guidance suggest that the front will struggle to
push through keeping many sites in the low to mid 30s. May see some
warming on the south coast to near 40F but it will be a struggle.

Any lingering precip from the morning hours will be spotty and very
light as the better lift continues to remain north of the region.
However profile is still quite saturated so any forcing could help
result in some showers. Depending on surface temps this could be
snow or rain. Precip chance for the afternoon into the evening will
linger across northeast MA as meso-low moving into coastal ME seems
to develop some sort of inverted trough over that region. With this
lingering moisture combined with increase 950mb warm layer, could
see some freezing rain by later afternoon into evening hours. This
could result in impacts to the evening commute in northeast MA. This
is shown in BUFKIT soundings especially for BVY, LWM and BED. It will
be close for BOS.  Confidence is to low, and precip could be quite
spotty so will hold off on winter weather adv for now. Something the
overnight shift may want to look at.

Shower chances decreases by the late evening resulting in a dry
forecast for Monday night. Temperatures will remain steady as weak
warm front pushes northward.


&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...

Highlights...

* Much milder Tue with mainly dry weather
* Turning blustery and colder Wed into Thu with dry weather
* Mainly rain Fri night/Sat with some wind and mild temps favored
* Unsettled weather possible sometime Christmas Eve into Christmas

Details...

Tuesday...

Much milder weather expected on Tuesday with 850T near 0C and
southwest flow ahead of a cold front.  High temps should reach into
the upper 40s to near 50 with even some lower 50s possible in the
coastal plain.  Dry weather anticipated with the lack of synoptic
scale forcing, but can not rule out a spot shower or two toward
evening in western MA.

Tuesday night and Wednesday...

A cold front crosses the region region Tue night into early Wed with
colder/blustery weather to follow.  Mainly dry weather anticipated
other than perhaps a few brief rain/snow showers across the east
slopes of the Berkshires. Increasing wind will keep low temps Tue
night mainly in the upper 20s to the lower 30s. High temps on Wed
will generally be in the 30s to around 40, but northwest wind gusts
of 25 to 40 mph will make it feel colder.

Wednesday night and Thursday...

Canadian high pressure builds into the region bringing dry but cold
weather.  Low temps Wed night should mainly be in the teens, but
some single digits can not be ruled out in the normally coldest
outlying locations.  High temps on Thu should mainly be in the
lower to middle 30s, but with less wind than on Wed.

Friday and Saturday...

Upper level ridging will be building across the southeast states as
a shortwave trough lifts northeast towards the Great Lakes.  While
it is too early to completely lock in a solution...the given pattern
and ensemble guidance strongly favors low pressure passing to our
northwest putting us on the mild side of the storm.  Timing still
uncertain, but most guidance keeps the daytime hours dry with bulk
of the rain Friday night and/or Saturday.  Now there initially is
still Canadian High pressure which slides off to the east, so can
not rule a bit of snow/ice at the onset across the interior.
Nonetheless, mainly rain is favored Friday night into Saturday
across the entire region.  In fact, temps could climb well into the
50s to near 60 for a time along with a period of strong southerly
winds.

Christmas Eve into Christmas...

Very low confidence forecast in this time range.  Upper level ridge
with abnormally high height fields will be anchored off the
southeast coast.  Meanwhile, a dome of arctic air and well below
normal temperatures will be invading much of the central states.
This will place our region in the battle ground between these
extreme airmasses.  A couple waves of low pressure will likely track
along the baroclinic zone and bring the risk for a period or two of
precipitation sometime Christmas Eve into Christmas. Timing/ptypes
and will depend on exactly where the baroclinic zone aligns. While
snow is certainly an option especially at this time range...given
strength of southeast upper level ridge would favor rain/ice.  If we
do have enough cold air for wintry precipitation, it might end up
coming down shallow given rather high height fields.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Short Term /through Monday Night/...High confidence.

After 00z...Mainly VFR with gradually lowering cigs, becoming
MVFR after 06z. Patchy light snow possible.

Monday...Widespread MVFR cigs with a few spots lowering IFR.
Chance of light snow north of the Pike and rain south of the
Pike. Precip will wind down by the afternoon. Lingering showers
in Northeast MA could result in a wintry mix resulting in slick
runways.

Monday night...Improving conditions to VFR during the overnight.

KBOS Terminal...High confidence in trends. Spotty snow showers
during the morning push. May have to watch for light FZRA after
21z. Low confidence if this will occur.

KBDL Terminal...High confidence. Spotty snow showers during the
early morning hours coming to an end before 15z.

Outlook /Tuesday through Friday/...

Tuesday: Mainly VFR, with local MVFR possible. Windy with gusts
to 30 kt.

Tuesday Night: Mainly VFR, with local MVFR possible. Windy with
gusts to 35 kt.

Wednesday: VFR. Windy with gusts to 35 kt.

Wednesday Night through Thursday: VFR. Breezy.

Thursday Night: VFR.

Friday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Short Term /through Monday Night/...High confidence.

Tonight...Light winds and seas.

Monday...Winds becoming SW and increasing in the afternoon but
gusts below 20 kt. Seas below SCA. Chance of light snow changing
to rain.

Monday night...Dry weather with increasing winds and seas.
Conditions remain below SCA.

Outlook /Tuesday through Friday/...

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Local rough seas.

Tuesday Night: Moderate risk for gale force winds with gusts up
to 35 kt. Areas of rough seas.

Wednesday: Low risk for gale force winds with gusts up to
35 kt. Areas of rough seas.

Wednesday Night: Moderate risk for Small Craft Advisory winds
with areas of gusts up to 30 kt. Local rough seas.

Thursday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft.

Thursday Night: Winds less than 25 kt.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$
SYNOPSIS...Frank/Dunten
NEAR TERM...Dunten
SHORT TERM...Dunten
LONG TERM...Frank
AVIATION...Frank/Dunten
MARINE...Frank/Dunten

NWS BOx Office Area Forecast Discussion