Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 261834
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
234 PM EDT Tue Mar 26 2024

.SYNOPSIS...

Damp and chilly day continues with raw northeast winds, drizzle, and
fog, especially across eastern Massachusetts. Considerably
milder Wednesday, but a continued risk for showers. A frontal
wave will bring more widespread rain Thursday into early Friday,
which may lead to renewed flooding concerns. Drying out later
Friday into Saturday, but there remains uncertainty in the exact
timing. Dry and seasonable next weekend, but blustery on
Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...

Moisture continues to be pulled into southern New England this
afternoon and evening on NE flow around the occluded low well to
our south. Thus, clouds continue even though the bands of light
showers and drizzle have diminished by this afternoon. Even so,
will continue to see these impact the eastern half of the
region, especially east coastal MA off and on. Tonight a subtle
shortwave lifts through the broader SW flow ahead of an
approaching shortwave. However, it is accompanied by drier air
moving in from the south which should limit shower coverage.
BUFKIT soundings do show some marginal drying in the low levels
along the east coast, but even so would expect spotty drizzle
and fog. Lows will be milder than the previous night as
increasing dewpoints limit temps to the low to mid 30s.

&&

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

A subtle mid level disturbance moves overhead Wednesday rotating
around a very broad trough over the entire eastern half of the U.S.
For much of the day the plume of deeper moisture ahead of the trough
remains to our south, while the dynamics also are removed from our
area, so shouldn`t see much in the way of rain during the day.
The exception may be the orographically favored terrain of
western MA. Something of note will be the milder temperatures
compared to Tuesdays as low level flow moderates. Dewpoints rise
into the upper 40s/low 50s and while there is some disagreement
between the global and hi- res guidance, even ensembles show a
40-60% chance of surface temps reaching as high as 60 degrees in
RI and southeast MA.

Wednesday night the plume of moisture (>1" PWATs) originating from
the Gulf of Mexico reach southern New England ahead of an area of
low pressure moving up the east coast. This is the front end of what
will be a prolonged period of widespread moderate rainfall. The
synoptic forcing for ascent will be increasing thanks to divergence
aloft from a 150 kt upper jet as the upper trough and surface low
approach. By sunrise on Thursday, can`t rule out a half inch or more
of rainfall.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...

Highlights

* Heavy precipitation late week may lead to an elevated risk for
  flooding across RI and southeastern MA

* Trending drier with near normal temperatures this weekend

Looking like southern New England is heading into a prolonged period
of unsettled weather late this week. Significant ensemble signals in
the NAEFS, with standardized anomalies of 3-4 standard deviations.
We`re looking at quite a bit of moisture and lift sometime from
Thursday into Friday a a coastal low pressure moves by to our east.
Given this storm track, the greatest risk for rainfall will be
across the Cape and islands, but there should be at least some
rainfall across most of southern New England during this time. There
is potential for another 1-2 inches of rainfall in our region, which
will need to be monitored with area waterways already running high
from the rainfall this past Saturday. Should confidence in
significant rainfall continue to increase, Flood Watch headlines may
be needed for portions of southern New England.

Still thinking this weekend remains mainly dry, but the picture is
not as clear as it once was. A low pressure should move into the
Maritimes from east of New England by Saturday. The question then
becomes where exactly will the cold front of this low pressure be.
At this time, thinking it stalls just to the south of New England.
With another low pressure projected to develop over the central USA
at this time, providing another mechanism to keep this front nearby.
This low pressure itself is projected to pass by to our south on
Sunday, but not far enough south to prevent some clouds from
reaching our region. Saturday looks to be the windier of the two
days, as some cooler air arrives on the back side of the departing
low pressure.

Weak high pressure should then continue into Monday, before another
low pressure possibly arrives towards next Tuesday.

Near to slightly above normal temperatures anticipated through this
portion of the forecast.

&&

.AVIATION /18Z TUESDAY THROUGH SATURDAY/...
Forecast Confidence Levels:

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

18Z Update...

This afternoon...high confidence on trends, lower on exact
details and timing.

MVFR/IFR conditions overspread the region from SE to NW today,
with much of the region IFR by late today, with areas of LIFR
possible late across Cape and Islands. Bands of light rain and
drizzle continue. NE winds remain gusty 15-25 kt, except up to
35 kt along the coast, slowly easing late in the day.

Tonight...high confidence.

IFR/LIFR in low clouds, spotty light rain, drizzle and areas of
fog. NE winds ease and become SE late.

Wednesday...moderate confidence.

Drier on Wednesday with IFR/LIFR early improving to MVFR/VFR by
after non. Light and variable winds in the AM becoming SSE in
the afternoon.

Wednesday night...moderate confidence.

VFR to start lowering to IFR/LIFT in increasingly widespread
moderate rain showers. Light and variable winds becoming
northerly.

KBOS TAF...High confidence in trends, some uncertainty in exact
timing and details.

KBDL TAF...High confidence in trends, some uncertainty in exact
timing and details.

Outlook /Thursday through Saturday/...

Wednesday Night: MVFR/IFR conditions possible. Chance RA,
patchy BR.

Thursday: Mainly IFR, with areas MVFR possible. RA.

Thursday Night: MVFR/IFR conditions possible. Windy with local
gusts up to 30 kt. Chance RA.

Friday: VFR. Windy with gusts up to 35 kt. Chance RA.

Friday Night: VFR. Windy with gusts up to 35 kt.

Saturday: VFR. Windy with gusts up to 30 kt.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight...

High pressure moves over the Maritimes and low pressure south
of New England weakens. Winds weaken and shift from NE to SE.
Rough seas slowly subside. Vsby limited in areas of light
rain/drizzle and fog.

Wednesday...

Weak high pressure over the waters; winds light and variable.
Drizzle and fog during the morning slowly give way to drier
weather in the afternoon along with improving vsby. Seas 5-7
ft.

Wednesday night...

Rain shower coverage increasing through the nighttime hours.
Winds light and variable. Seas 4-6 ft.

Outlook /Thursday through Saturday/...

Wednesday Night: Winds less than 25 kt. Local rough seas. Rain
likely, patchy fog. Visibility 1 to 3 nm.

Thursday: Winds less than 25 kt. Seas up to 5 ft. Rain. Local
visibility 1 to 3 nm.

Thursday Night: Low risk for Small Craft Advisory winds with
local gusts up to 30 kt. Areas of rough seas. Rain.

Friday: Strong winds with gusts up to 30 kt. Rough seas up to
9 ft. Chance of rain.

Friday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 8 ft. Slight chance of rain.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 9 AM EDT Wednesday for ANZ230.
     Small Craft Advisory until midnight EDT tonight for ANZ231>235-
     237.
     Small Craft Advisory until 8 PM EDT this evening for ANZ236.
     Small Craft Advisory until 8 AM EDT Thursday for ANZ250-251-
     254>256.

&&

$$

SYNOPSIS...Belk/BW
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...Belk
AVIATION...Belk/BW
MARINE...Belk/BW


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