049
FXUS61 KBOX 242327
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
727 PM EDT Fri May 24 2024

.SYNOPSIS...
Warm and mostly dry conditions this weekend, but a few afternoon
thunderstorms are possible Sunday. A slow moving front may bring
significant rainfall Monday afternoon into Monday night. Drying out
Tuesday, then unsettled weather pattern sets up again from mid week
into next weekend with cooler temperatures.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Cold front across northern New Eng will push south into SNE this
evening and move off the south coast overnight. Dry frontal passage
as moisture and convergence is limited. Just an area of enhanced
cloud cover along the front but these clouds will diminish as they
approach SNE. Looking at mainly clear skies tonight with diminishing
wind this evening then turning light north behind the boundary later
tonight. Decent  cooling develops overnight with lows
dropping to low-mid 50s, but upper 40s in colder locations in
western MA and possibly interior E MA.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Saturday...

High pres will be in control with abundant sunshine during the
morning, then high clouds will be increasing during the afternoon as
mid-high level moisture begins to increase from the west. Slightly
cooler airmass Sat with 925 mb temps 16-18C leading to highs mostly
in the 70s, but lower 80s more likely in the CT valley and Merrimack
valley. Sea-breezes will develop holding temps in the upper 60s and
lower 70s near the immediate coast and Cape Cod.

Saturday night...

A modest W-SW low level jet will transport higher moisture into SNE
as PWATs increase to around 1.25". Some weak elevated instability
also develops which may lead to a few showers developing in the
interior, but area coverage will likely be limited. Lows will be in
the 50s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Highlights

* Mix of sun and clouds on Sunday with some afternoon thunderstorms
  possible

* Substantial rain event Monday afternoon into Tuesday morning

* After a brief dry out Tuesday into Wednesday morning, an unsettled
  weather pattern looks to dominate the Northeast for the foreseeable
  future

Sunday

High pressure shifts to the east on Sunday allowing south winds to
advect higher dewpoints into southern New England. As a result,
increased low-level moisture will result in more cloud cover than
the previous two days, but there should still be a good amount of
sunshine for most of the day as well. Background wind field may be
weak enough to support a sea-breeze along the coastline. Model
forecast soundings suggest a fair amount of instability may be
available on Sunday to support thunderstorm development in the
afternoon. Deep layer moisture is forecast to be lacking across most
of the areas west of I-495, but model guidance suggests more mid-
level moisture availability across eastern MA. If a sea-breeze
boundary develops, low/mid-level lapse rates, sufficient
instability, and up to 30 knots of deep layer shear would likely be
enough to support a few afternoon thunderstorms with a sea-breeze
boundary providing the necessary lift. Only FV3 and NAMNest Hi-Res
models are available at this time as they extend out to 60 hours,
and each are resolving convection over southern New England Sunday
afternoon. More details will become available as the rest of the
HREF members and their 48 hours become available tonight and
tomorrow. Temps will be upper 70s/low 80s across the interior and
cooler along the coast in the upper 60s/low 70s.

Monday and Tuesday

Substantial rainfall is likely Monday afternoon into Tuesday morning
as a low-pressure system moves across The Midwest/Great Lakes
region. Monday looks to feature mainly overcast skies and periods of
warm frontal precipitation. As moisture increases ahead of the
associated cold front Monday night into Tuesday, more substantial
rainfall is likely Monday night into Tuesday morning with PWATs up
to 1.75" potentially supporting rainfall accumulations of an inch or
greater by Tuesday morning. The consensus among latest guidance is
for a dry slot to work its way over the region by late Tuesday
morning/early Tuesday afternoon to allow for a salvageable spring day
on Tuesday.

Wednesday and beyond

By mid-week a second upper-level disturbance will dig down from The
Midwest and settle over The Northeast. A near -20 Celsius upper cold
pool at 500 hPa looks to become quasi stationary over The Northeast
through the end of next week. This will support unsettled weather
and below normal temperatures that may persist through the end of
next weekend.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:

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

00Z TAF Update

Tonight...High confidence.

VFR, but patchy stratus/fog may impact ACK this evening. W-SW
gusts to 25 kt diminishing this evening and becoming light N
overnight.

Saturday...High confidence.

VFR. S-SW wind near 10 kt developing Sat afternoon with sea-
breezes along the coast.

Saturday night...Moderate confidence.

Mainly VFR, but patchy MVFR-IFR stratus and fog possible
overnight. Areal coverage of lower conditions is uncertain.
A few showers possible in the interior.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Sunday through Wednesday/...

Sunday: VFR. Slight chance SHRA, isolated TSRA.

Sunday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA, isolated TSRA.

Memorial Day: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA.

Monday Night: MVFR/IFR conditions possible. Breezy. SHRA
likely, isolated TSRA.

Tuesday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA.

Tuesday Night through Wednesday: VFR. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Saturday night...High Confidence.

A few G25 kt over eastern MA nearshore waters this afternoon, then
winds diminish this evening becoming light N overnight. Light winds
Sat morning becoming S-SW 10-15 kt Sat afternoon and night. Seas
below SCA.

Outlook /Sunday through Wednesday/...

Sunday: Winds less than 25 kt. Slight chance of rain showers.

Sunday Night: Winds less than 25 kt.

Memorial Day: Winds less than 25 kt. Slight chance of rain
showers.

Monday Night through Tuesday: Winds less than 25 kt. Seas up to
5 ft. Chance of rain showers, isolated thunderstorms.

Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers.

Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...KJC/RM
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...RM
AVIATION...KJC/RM
MARINE...KJC/RM