Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 060830
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
330 AM EST Mon Feb 6 2023

.SYNOPSIS...
Ocean storm passes well SE of New England today then high
pressure builds in from the west late tonight and Tuesday with
colder conditions. Scattered rain/snow showers Tuesday night
with a frontal system, then turning milder again through the end
of the week with temperatures well above normal, especially
Friday. Another frontal system will bring rain Thursday into
Thursday night followed by drier and unseasonably mild weather
Friday. Rain chances increase again Friday night into Saturday
as a storm lifts NE from the Ohio Valley and into New England.
Blustery and colder conditions behind the storm Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Amplifying mid level trough from the Gt Lakes moves into New Eng
today. Flow is backing and bringing southern stream moisture
northward, but deep moisture remains mostly offshore. As a result,
bulk of the rain will stay to the south and east but the western
extent will likely just clip the outer Cape/Islands this morning.
Stratus and fog also expected to develop over Cape/Islands this
morning. Most sunshine today will be in the interior but expect
partial sunshine developing further E away from the coast. Clouds
will linger near the coast.

As storm deepens to the east, expect increasing N winds this
afternoon. Soundings support 20-30 mph gusts mid/late afternoon with
35 mph gusts Cape/Islands. Airmass remains mild today with 925 mb
temps cooling to 0-2C this afternoon. With good mixing, temps
expected to reach 45-50 across much of the region.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Tonight...

Windy conditions along the coast this evening with strong pressure
in place. Favorably mixed boundary layer supports 25-30 mph gusts
near the coast and 35-40 mph gusts Cape/islands. ACK may see a
period of 45 mph gusts but confidence not high enough to issue a
wind advisory. Winds gradually diminish after midnight as high pres
builds in from the west.

Clearing develops in the west this evening and spreads E tonight.
However, may see some ocean effect strato-cu linger over the
Cape/Islands. A window for decent radiational cooling overnight in
the interior as winds diminish so we blended in colder MOS guidance
here. Expect lows to drop into the teens interior MA, with 20s
elsewhere.

Tuesday...

High pres ridge over New Eng will shift to the east in the afternoon
with southerly flow developing. Sunshine will give way to increasing
clouds in the afternoon as next mid level trough and shortwave
approaches from the Gt Lakes. Deeper moisture axis with the cold
front remains to the west so expect dry weather through the day,
with precip chances increasing toward evening. Cold start to the day
and with rather shallow mixed layer below 950 mb, it will a cooler
day with highs upper 30s to lower 40s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Highlights...

* Well above average temperatures throughout next week, cooling down
  by the weekend

* Chance of light rain and snow showers Tuesday night then a series
  of more widespread wet weather systems arrives Thursday into the
  weekend.

Details...

After the brief respite from the highly anomalous temperatures on
Tuesday unusual warmth returns Wednesday and through the end of the
week. Wednesday mid level heights will be on the rise while low
level flow flips from the northeast to the southwest then west as a
surface trough passes over northern New England. This downslope flow
combined with a warmer airmass overhead (850 mb temps around +2C)
will bring surface temperatures back into the mid to upper 40s
Wednesday. Thursday may be a bit warmer but guidance is mixed. This
uncertainty involves the approaching shortwave which rounds the top
of the ridge on Thursday. A second, deeper trough moves through and
pushes the ridge out Friday into Saturday, and this sets us up for
the strongest warm advection and the warmest day of the week. While
deterministic guidance is indicating highs in the upper 50s
approaching 60, we`ll lean on ensemble guidance at this distance in
time. Both the GEFS and EPS indicate a 80-90%+ chance of temps over
50 F; for now will stick with temps mainly in the mid 50s, centered
over southeast MA. A cold front then brings more seasonable
temperatures for the weekend.

Precipitation-wise, there will be several rounds of wet weather. The
first comes Tuesday night as a weak and moisture starved frontal
system moves through. This will bring a short round of showers,
entering southern New England after sunset and exiting before
sunrise. Given the cold northerly flow much of Tuesday around the
offshore low there may be enough lingering cold air for these to be
light snow showers over much of the interior. Not expecting
impactful accumulations, though; a dusting to <1".

The more significant precipitation comes with the passage of a
vertically stacked low well to our northwest over the Great Lakes
into southeast Canada on Thursday into Friday. Given the far inland
track of the low which is well agreed upon by ensemble low center
guidance, this should be a mostly rain event. We may have to keep an
eye on potential for a period of wintry mix in the highest
elevations. A second, deeper shortwave then moves closer to southern
New England around the start of the weekend, but where the low
tracks (and the resulting precip type) is uncertain. Stay tuned.


&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels:

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

Through 12z...

MVFR/IFR conditions developing Cape/Islands 09-12z with stratus
and fog and areas of -RA. VFR elsewhere.

Today... High confidence.

IFR stratus and fog may linger across the outer Cape and
especially ACK into early afternoon with showers exiting ACK by
midday. Otherwise, VFR. Winds becoming this morning, increasing
this afternoon with 20-25 kt gusts developing and up to 30 kt
Cape/Islands.

Tonight... High confidence.

Mainly VFR, but areas of MVFR cigs may develop over
Cape/Islands. N wind gusts 25 kt near the coast but up to 35 kt
Cape/Islands. Winds diminishing overnight.

Tuesday... High confidence.

VFR, but may see some MVFR cigs Cape/Islands in the morning. N
wind gusts to 25 kt Cape/Islands diminishing by midday. Winds
turn southerly in the afternoon, increasing late in the day.

KBOS Terminal...High Confidence in TAF.

KBDL Terminal...High Confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Mainly VFR, with local MVFR possible. Windy with
areas of gusts up to 35 kt. Chance RA, chance FZRA.

Wednesday: VFR. Windy with areas of gusts up to 35 kt.

Wednesday Night: VFR.

Thursday: Mainly VFR, with local IFR possible. Breezy. RA
likely, patchy BR.

Thursday Night: Mainly VFR, with areas IFR possible. Windy with
gusts up to 30 kt. RA likely, patchy BR.

Friday: VFR. Windy with local gusts up to 30 kt. Slight chance
RA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through tonight... High confidence.

Winds becoming N this morning with rain exiting waters around
Nantucket this morning. Vsbys reduced in areas of fog this morning
across SE waters. Increasing N winds this afternoon into this
evening as coastal storm deepens well E of New Eng. Gusts to 35-40
kt expected, and we will have Gale Warnings for most of the waters.
Seas will build to 10+ ft over waters E of Cape Cod. Winds gradually
diminish overnight.

Tuesday... High confidence.

N wind gusts to 25 kt SE waters early, diminishing and becoming
easterly in the afternoon. Rough seas.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Slight chance of rain.

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

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

Thursday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Seas locally approaching 5 ft. Chance of rain, patchy
fog. Local visibility 1 to 3 nm.

Thursday Night: Low risk for gale force winds with gusts up to
35 kt. Seas up to 5 ft. Rain likely, patchy fog. Areas of
visibility 1 to 3 nm.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Local rough seas. Slight chance of rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 1 PM this afternoon to 3 AM EST
     Tuesday for ANZ230-236.
     Gale Warning from 3 PM this afternoon to 3 AM EST Tuesday for
     ANZ231-232-250-251-256.
     Gale Warning from 3 PM this afternoon to 1 AM EST Tuesday for
     ANZ233>235.
     Small Craft Advisory until 3 AM EST Tuesday for ANZ237.
     Gale Warning from 3 PM this afternoon to 5 AM EST Tuesday for
     ANZ254-255.

&&

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


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