NWS Technical Forecast Discussion

000
FXUS61 KBOX 182020
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
320 PM EST Tue Feb 18 2020

.SYNOPSIS...
Low pressure moves into the Maritimes late tonight. Dry weather
returns follows later tonight and it becomes windy on Wednesday
behind the passage of a cold front. Blustery and colder, dry
weather pattern Wednesday night through Friday with even colder
wind chills. Temperatures then moderate back to above-normal
levels by the weekend. Next Monday or Tuesday offers the next
chance for precipitation.

&&

.NEAR TERM /THROUGH TONIGHT/...
Light spotty rain south of the Pike with steadier precip to the
north. Snow mainly confined to interior northern MA but warm
nose aloft is advancing northward and will bring a change to
rain through late afternoon. Temps hovering around 32 over the
higher elevations may result in pockets of freezing rain before
temps rise above freezing by early evening. Max snow accum 2-3"
confined to NW MA.

Steadiest precip into this evening will be over the interior
with rain tapering off late this evening from west to east as
low level jet lifts to the NE with westerly flow developing.
Most locations should be dry by midnight with a few showers
possibly lingering over the Cape/Islands overnight. Low clouds
and patchy fog will impact the region this evening with partial
clearing toward daybreak as good low and mid level drying
develops.

Temps across SE New Eng expected to briefly spike into the
mid/upper 40s this evening as winds turn southerly. Otherwise,
cold front sweeps through overnight with temps falling back
into the 20s interior high terrain with mainly 30s elsewhere
across SNE. Gusty westerly winds developing late tonight over
higher terrain.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Wednesday...

Strong cold advection aloft will result in windy conditions.
Steep low level lapse rates with a well mixed boundary layer
will support NW gusts to 30-40 mph. The column is quite dry with
PWATs down to near 0.10" so expect plenty of sunshine which will
attempt to offset the cold advection. High temps will be mostly
in the 30s, but peaking in the lower 40s across RI and SE MA.

Wednesday night...

Continued cold advection with a secondary fropa as shortwave
passes to the north will keep the wind going although
diminishing somewhat. Mostly clear skies, but some ocean effect
clouds may skirt the outer Cape, and lake moisture may get
carried far enough east for some lower clouds to move into
western MA and northern CT. Lows will be mostly in the teens.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights...

* Colder, dry weather pattern for mid to late week, with below-
  normal temperatures and cold wind chills Thu and Fri.

* Possible ocean-effect snow showers with little accumulation South
  Shore/Cape Cod late Thu-Fri.

* Warming, moderating temperatures for the weekend with continued
  dry weather.

Rather quiet weather in store for southern New England through much
of this time. High pressure remains in control through this weekend.
Expecting dry weather to persist. With the core of this high
pressure to our west Thursday and Friday, winds will direct colder
air across our region, so looking at below normal temperatures
during this time. Gusty NW winds should lead to wind chill values in
the single digits above zero at times, especially early in the
mornings.

As this high pressure passes off to our south this weekend, we
return to the near to above normal temperatures we`ve seen most of
this winter. Those temperatures should linger into the middle of
next week.

As for precipitation, there is a low risk for some ocean-effect
showers across the eastern coastal waters Thursday and Thursday
night. These will be more likely to remain farther offshore, as the
wind direction may be too much from the NW. Otherwise, the next
significant chance for precipitation looks to be sometime Monday
into Tuesday, from a cold front Monday, then a possible coastal low
pressure Tuesday. Still too early to focus on those details, but at
this time thinking more of a mixed precipitation event.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

18z TAF update...

Through 00z...
Conditions deteriorating to IFR with periods of rain. Snow
across interior northern MA changing to rain through 21-22z with
pockets of FZRA possible in higher elevations. Minor snow accum
over higher elevations.

Tonight...Moderate confidence.
Widespread IFR in rain this evening, with improving conditions
to VFR from west to east after midnight. But MVFR cigs lingering
over Cape/Islands through daybreak. NW gusts to 25 kt developing
over higher elevations after midnight.

Wednesday and Wednesday night...High confidence.
VFR. NW wind gusts of 25 to 35 knots.

Wednesday night...High confidence.
VFR. Diminishing wind.

KBOS Terminal...Moderate confidence in TAF. Trending to IFR by
this evening, improving after midnight.

KBDL Terminal...Moderate confidence in TAF. Trending to IFR
late this afternoon, improving around midnight.

Outlook /Thursday through Sunday/...

Thursday: VFR. Breezy.

Thursday Night through Friday: VFR.

Friday Night through Saturday: VFR. Breezy.

Saturday Night through Sunday: VFR.

&&

.MARINE...
Tonight...High confidence. Low level jet lifting across the
waters will result in a period of SE gusts to 30 kt through
early this evening then winds diminishing and shifting to SW
then W. Wind speeds ramp up again late tonight. Vsbys reduced in
spotty rain and fog this evening with patchy fog continuing
overnight over southern waters.

Wednesday...High confidence.
NW gusts 25-35 kt with strong cold advection place. Gale
warnings for NE MA open waters with SCA elsewhere.

Wednesday night...High confidence.
Winds slowly diminish through the night but SCA conditions will
persist over the open waters with hazardous seas.

Outlook /Thursday through Sunday/...

Thursday through Thursday Night: Winds less than 25 kt. Areas
of seas approaching 5 ft.

Friday: Winds less than 25 kt.

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Saturday through Saturday Night: Winds less than 25 kt. Areas
of seas approaching 5 ft.

Sunday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory until 5 PM EST this afternoon for
     MAZ002-008-009.
RI...None.
MARINE...Small Craft Advisory until 1 AM EST Thursday for ANZ231>234.
     Small Craft Advisory from 7 AM to 9 PM EST Wednesday for
     ANZ230-236.
     Small Craft Advisory until 4 AM EST Thursday for ANZ235-237.
     Gale Warning from 7 AM to 9 PM EST Wednesday for ANZ250.
     Gale Warning from 7 AM to 7 PM EST Wednesday for ANZ251.
     Small Craft Advisory until 7 AM EST Thursday for ANZ254>256.

&&

$$
SYNOPSIS...Belk/KJC
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Belk
AVIATION...Belk/KJC
MARINE...Belk/KJC

NWS BOX Office Area Forecast Discussion

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