Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 020319
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1019 PM EST Mon Mar 1 2021

.SYNOPSIS...
Arctic cold front moves through Srn New England overnight. This
will bring widely scattered snow showers and strong gusty
northwest winds. Additionally, temperatures drop well below
normal and are accompanied by sub-zero wind chills for Tuesday
morning. A brief warmup expected on Wednesday with above normal
temperatures, then a return to somewhat colder weather late in
the week through the weekend, but mainly dry condition should
prevail.

&&

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

Upper low moves over the Canadian border, with an associated
cold pool aloft sweeping over Srn New England. This cold
advection aloft will destabilize the airmass overnight,
generating bands of snow showers/squalls. Satellite images at 10
PM showed numerous west-east bands across the region. Working
against this will be the downhill movement of the air and
advection of lower dew points from NY State. Both will work
toward minimizing the effects of the snow...mostly a thin
coating on the ground. The trend of colder temps aloft will
ease toward morning, so expect eventual clearing skies.

Winds forecast to 50 kt at 850-mb and 35-40 kt at 950-mb, so
expect wind gusts of 40-50 kt/45 to 55 mph. With pockets of
55-kt winds forecast aloft, can`t rule out a few gusts of 60-65
mph. This wind combined with the chilling temperatures will
generate wind chills of -15F in NW Mass and wind chills at or
below zero across the rest of Srn New England.

The Wind Advisory continues for much of Srn New England
overnight. The Wind Chill Advisory continues for NW Mass
overnight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday: An area of weakening high pressures will slide across the
southern Ohio Valley, this pushes a surface low out into the Saint
Lawrence Gulf. Winds will ease during the first half of the day
though it will remain rather chilly with highs in the 20s to lower
30s at the coast.

Tuesday Night: The weakening high pressure slides south and lowering
pressure to the north, that will result in increasing clouds
overnight. Winds aloft will shift from NW to SW and help usher in
slightly warmer temperatures. This coupled with the cloud cover
should yield overnight lows in the upper teens across the interior
to the low 30s at the coast.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Highlights...

* Mild and dry Wed

* Turning colder for the end of the week into the weekend with
  below normal temps

* Mainly dry through the period

Overview...

Developing -AO/-NAO pattern through the end of the week and into the
weekend as Greenland block sets up. Piece of TPV will locked in
across eastern Canada with troughiness over the NE and New Eng.
Result will be a trend toward colder temps averaging below normal
from Thu through the weekend with Fri/Sat likely the coldest days of
the period. This will be preceded by a relatively mild day on Wed
with above normal temps.

Precip wise, it looks like a rather quiet period with mainly dry
conditions right through the weekend and into early next week. There
are multiple shortwaves rotating around the vortex in eastern Canada
but moisture is limited and outside of a few brief flurries/snow
showers, expect mainly dry conditions. Weekend ocean storm is
expected to pass well SE of New Eng and not pose a risk.

There is decreasing forecast confidence as we head toward the end of
the weekend into early next week on how quickly the pattern breaks
down which impacts temp forecast. GFS is quicker than ECMWF lifting
out the trough and building the SE ridge which brings milder temps
to the region Sun/Mon. We leaned toward slower ECMWF solution as GFS
typically has a progressive bias, so we have temps remaining below
normal. It does appear pattern change eventually takes place during
next week with a transition to +AO/+NAO/-PNA and milder weather.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels.

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

Overnight...High confidence.

VFR with strong NW gusts to 45 kts. There may be a few 50 kt
gusts over higher terrain and Cape/Islands per GFS/NAM BUFKIT
soundings. Isolated brief MVFR/IFR snow showers/squalls passing
through 03-06z.

Tuesday...High confidence.

VFR with gusty WNW to NW winds to start. Expecting gusts of
30-45 kts to start. Winds and gusts diminishing during the
afternoon. Should see gusts falling to 15-30 kts.

KBOS TAF...High confidence in trends. Expect a period of
IFR/LIFR into the AM push, improving to VFR in the afternoon.

KBDL TAF...High confidence in trends. Expect a period of
IFR/LIFR into the AM push, improving to VFR in the afternoon.

Outlook /Wednesday through Saturday/...

VFR. Breezy.

&&

.MARINE...
We`ve upgraded all our waters to Storm Warnings for gusts between 60
and 65 MPH, the only exception are Narragansett Bay and Boston
Harbor where Gale Warnings are still in effect. We expect these
gusty winds to persist through early Tuesday afternoon. On top of
this have widespread moderate freezing spray still expected with an
arctic airmass moving in. The Freezing Spray Advisory previously
issued into for tonight into Tuesday morning still looks good.

Outlook /Wednesday through Saturday/...

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

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

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

Thursday Night through Friday: Moderate risk for Small Craft
Advisory winds with gusts up to 25 kt. Areas of rough seas.
Chance of freezing spray.

Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.

Saturday: Winds less than 25 kt. Seas up to 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Wind Advisory until 10 AM EST Tuesday for CTZ002>004.
MA...Wind Advisory until 10 AM EST Tuesday for MAZ002>006-008>021-
     026.
     Wind Chill Advisory until 10 AM EST Tuesday for MAZ002>004-008-
     009-026.
     Wind Advisory until 1 PM EST Tuesday for MAZ007-022>024.
RI...Wind Advisory until 10 AM EST Tuesday for RIZ001>008.
MARINE...Storm Warning until 8 AM EST Tuesday for ANZ232>234.
     Freezing Spray Advisory until 1 PM EST Tuesday for ANZ231>237-
     250-251-254>256.
     Gale Warning until 7 PM EST Tuesday for ANZ230.
     Storm Warning until 1 PM EST Tuesday for ANZ231-251.
     Gale Warning until 4 PM EST Tuesday for ANZ236.
     Storm Warning until 7 AM EST Tuesday for ANZ235-237.
     Storm Warning until 1 PM EST Tuesday for ANZ250-254.
     Storm Warning until 10 AM EST Tuesday for ANZ255-256.

&&

$$
SYNOPSIS...WTB/KJC/Gaucher
NEAR TERM...WTB/Gaucher
SHORT TERM...Gaucher
LONG TERM...KJC
AVIATION...WTB/KJC/Gaucher
MARINE...WTB/KJC/Gaucher



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