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Area Forecast Discussion

Forecast Discussion for BOX NWS Office
000
FXUS61 KBOX 170017
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
717 PM EST Sat Jan 16 2021

.SYNOPSIS...

Low pressure in northern New England will lift into Quebec
bringing dry & blustery weather tonight and Sunday. More
seasonable temperatures arrive for much of the next work week.
Several opportunities for light snow showers especially across
the higher elevation of the interior. Snow showers may be a bit
more widespread Thursday into Friday.

&&

.NEAR TERM /THROUGH SUNDAY/...

700 PM Update...

Have slowed down the clearing skies expected until late tonight
based on satellite observations and high resolution guidance. In
addition, increased overnight lows a bit as we were a bit too
cool based on current observations. Remainder of the forecast is
on track.

310 PM Update...

The low pressure system that brought us the earlier heavy rain,
coastal wind and even heavy wet snow in the high terrain of far
northwest MA has lifted into northern New England. There were
just a few left over showers across northeast MA with the
surface trough, but these should be exiting the region shortly.

Low pressure will continue to move north and into northern Main
tonight. Southwesterly flow on the backside of this system will
result in mainly dry weather tonight. The exception to this
should be in far western MA...mainly the east slopes of the
Berkshires where scattered snow showers are anticipated at
times. This a result of upper level energy combined with
leftover Lake Effect moisture. This may result in an inch or
two of snow in far northwest MA. We will continue a dry forecast
elsewhere, although a brief spot rain or snow shower can not be
ruled out it is not worth including in the forecast.

Southwest winds will become blustery late tonight across
portions of the high terrain/coastal locations. This a result of
intensifying low pressure across northern New England. Low temps
will become cooler, but only bottom out in the upper 20s to
middle 30s by daybreak. These readings will still be about 10 to
15 degrees above normal.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH 6 PM SUNDAY/...

Sunday...

Low pressure will continue to intensify as it moves north into
Quebec and should drop to around 975 mb on Sunday. This
increased pressure gradient coupled with diurnal mixing should
result in a rather windy day. Overall, expect westerly wind
gusts of 25 to 40 mph to develop. However, we may be flirting
with wind advisory criteria across the Cape/Islands. Given it is
marginal will defer to the next shift.

Mainly dry weather should prevail, but a few snow showers will
be possible mainly in the distant interior /east slopes of the
Berks/ as a result of some remnant Lake Effect moisture on
westerly flow.

The airmass behind this system is not too cold for January
standards. So with a mixture of clouds and sunshine, expect
Sunday afternoon high temperatures to range from the upper 30s
in the highest terrain to the lower to middle 40s elsewhere. It
will feel colder given the windy conditions, but it is January
after all.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...

Highlights

* Unsettled with several opportunities for snow showers - Monday,
  and Wednesday through Friday.

* Above normal temperatures on Monday. Temperatures will be more
  seasonable for the rest of week.

Progressive pattern through the extended with several opportunities
for snow showers especially across the higher elevations of the
interior.

Sunday night through Monday...

Ridge axis over the Mid Atlantic on Sunday night will flatten out
and build into Nova Scotia by late Monday. A neutrally tilted trough
will lift from the TN/OH Valley into the Mid Atlantic by Monday
morning and through southern New England during the day. At the
surface a prefrontal trough slides through Sunday night into early
Monday, and a cold front moves through on Monday.

Have increased precipitation chances Sunday night through Monday.
The combination of low to mid level moisture, the trough moving in
and the surface forcing should allow for isolated to scattered snow
shower activity. The best chance for snowfall will be across the
higher elevations of western MA and CT. Could even see some flakes
across central MA/RI, but have more confidence across the west. For
now have slight chance to chance where confidence is highest and
borderline slight chance elsewhere. May need to see central MA and
RI precip chances increase in future updates.

Will have W to WNW 0 to -5 degree Celsius cold air advection at 925
hPa Sunday night through Monday. Despite this will have above normal
temperatures for this time of year. Low temperatures for Sunday
night into Monday will be in the 20s across the higher elevation to
the 30s elsewhere. Should see a bit of downsloping due to the
westerly flow on Monday. The higher elevations will see highs in the
30s. Elsewhere readings will be in the low to mid 40s.

Monday night through Tuesday...

Trough just east of the region will lift through Nova Scotia Monday
night. Ridge axis will build from the eastern Great Lakes into the
Gulf of Maine and flatten out by Tuesday morning. A shortwave trough
will lift from the western Great Lakes early on Tuesday into the
eastern Great Lakes.

Generally expecting dry and quiet weather through this period as a
weak high builds in. Cloud cover will increase later on Tuesday as a
broad low lifts across the Great Lakes - cannot completely rule out
a snow shower across the eastern slopes of the Berkshires by late in
the day.

Will be chilly in comparison to the past couple of days, but really
temperatures will be trending toward seasonable readings. Expect W
to NW cold air advection to advect in -4 to -7 degree Celsius 925
hPa air. Low temperatures for Monday night into Tuesday will
generally be in the 20s. Highs on Tuesday will be in the 30s.

Tuesday night through Friday...

Progressive pattern continues with the shortwave trough sliding
through Tuesday night through Wednesday. Ridge axis builds in for
Wednesday night into Thursday. Another shortwave swings through on
Thursday and Friday.

Have slight chance to chances of precipitation as the shortwaves
move through. Given there are time and intensity differences of the
waves moving through during this timeframe, have gone with the NBM
guidance. Still appears that the best chance of snowfall will be
across the higher elevation, but precipitation may be a bit more
widespread on Thursday into Friday as a secondary low may develop
nearby/over the region. Still too early for the specifics given the
differences amongst guidance this far out.

Temperatures will be near normal for this time of year during this
period with highs in the 20s and 30s, but could moderate into the
low 40s along the south coast by Friday. Will be quite chilly
Wednesday night into Thursday as high pressure briefly builds in.
Readings range from the single digits across the higher elevations
to the teens and low 20s elsewhere.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...

Forecaster Confidence Levels.

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

Through 12Z...High confidence

Mixture of MVFR and VFR to start, but should see improvement to
VFR from southwest to northeast as drier air works its way in. WSW
winds of 10 to 15 knots increasing across the high terrain,
Cape and Islands to between 15 and 25 knots after midnight with
gusts of 25 to 30 knots. Dry weather other than a few snow
showers mainly along the eastern slopes of the Berkshires.

Sunday...High confidence

Anticipate VFR conditions, but should see some MVFR across the
higher terrain of MA with ceilings around 1.5-3 kft. Lowest
ceilings are most likely over the eastern slopes of the
Berkshires. Gusty WSW winds with speeds of 10 to 20 kts and
gusts of 25 to 35 knots across most of the region, but on the
order of 35 to 40 knots possible for the Cape/Islands. Still may
have a few a few snow showers across the interior mainly along
the east slopes of the Berkshires.

Sunday Night...High confidence

Generally expecting MVFR conditions, but may see MVFR with
localized IFR across the eastern slopes of the Berkshires. Gusty
WSW winds to start, but winds diminishing as the night
progresses.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Monday through Thursday/...

Martin Luther King Jr Day: Mainly VFR, with local MVFR
possible. Breezy.

Monday Night through Wednesday: VFR. Breezy.

&&

.MARINE...

Tonight and Sunday...High Confidence.

There will continue to be a temporary lull in the winds through
the first half of the evening. However, intensifying low
pressure lifting across northern New England and into Quebec
will result in WSW 30 to 40 knot wind gusts developing. Gale
Warnings are in effect for all waters late tonight and Sunday.
Seas over the open waters will remain quite high.

Outlook /Sunday Night through Thursday/...

Sunday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 13 ft.

Sunday Night: Low risk for gale force winds with gusts up to
40 kt. Rough seas up to 13 ft.

Martin Luther King Jr Day through Monday Night: Moderate risk
for Small Craft Advisory winds with gusts up to 25 kt. Areas of
rough seas.

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas.

Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Slight chance of snow
showers.

Wednesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Slight chance of snow
showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning from 10 PM this evening to 10 PM EST Sunday for
     ANZ231>235-237-250-251-254>256.
     Gale Warning from 8 AM to 6 PM EST Sunday for ANZ230-236.

&&

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

NWS BOX Office Area Forecast Discussion

 



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