Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 262352
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
752 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 WEDNESDAY/...
Only minor tweaks needed to the ongoing forecast this evening.
Clouds and areas of drizzle and fog already had settled in, and
should only expand overnight as humidity increases. Nearly
steady temperatures expected overnight, which would be above
normal for most locations.

Previous Discussion...

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 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 TUESDAY/...
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 /00Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

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

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
afternoon. Light and variable winds in the morning, becoming
SSE in the afternoon.

Wednesday night...moderate confidence.

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

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

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

Outlook /Thursday through Sunday/...

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 Sunday/...

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


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