802
FXUS61 KBOX 222332
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
732 PM EDT Thu May 22 2025

.SYNOPSIS...
A late season Nor`easter will slowly move into the Gulf of
Maine late tonight into Friday. Heavy rain and strong winds
will impact east coastal MA into this evening before the rain
and wind tapers off later tonight. The storm will be slow to
exit so a few lingering showers with unseasonably chilly
temperatures will persist Friday into Saturday. Drier weather
with gradually moderating temperatures are on tap for Sunday
and especially Memorial Day when parts of the region may
finally see highs break 70 degrees.

&&

.NEAR TERM /THROUGH FRIDAY/...
Key Messages:

* Heavy rain and nuisance street flooding will impact the afternoon
  and evening commute across eastern MA and portions of RI

* NE wind gusts of 40-50+ mph along the coast, especially Cape and
  Islands, with pockets of minor coastal flooding during the evening
  high tide

* The peak of the rain and wind will gradually taper off late this
  evening and overnight

Coastal low south of New Eng slowly tracks northward near Nantucket
this evening before lifting into the Gulf of Maine toward daybreak.
The peak of the heavy rain and wind will occur late afternoon and
evening as the low level jet axis lifts north across eastern New
Eng. Strong low level convergence at the nose of the jet combined
with favorable mid level low track will bring a period of heavy
rainfall to eastern MA which may extend into RI. Cloud tops are
cooling to the south and expect heavy rain to blossom as it lifts
north across eastern New Eng later this afternoon. There is also
some elevated instability at the edge of the dry slot which will
support a few t-storms over Cape/Islands and possibly eastern MA.

Strong signal in the HREF with high probs (up to 70 percent) of > 1"
in successive 3 hour periods focused across eastern MA. Potential
for 1-2 inches of rainfall in a 6 hour period with locally higher
amounts. Timing of heaviest rainfall will be around 4 pm to midnight
which will impact the evening commute with areas of urban and poor
drainage street flooding. Strongest winds will be focused over
Cape/Islands with peak gusts to 45-55 mph late afternoon and
evening, with strong gusts lifting north along the eastern MA coast
through midnight with gusts 35-45 mph.

Rain will begin to diminish after midnight as the low level jet
lifts to the north but periods of rain will continue overnight
across eastern New Eng, along with gusty N winds along the coast.
Interesting to note as the boundary cools with 925 mb temps
hovering near 0C, there could be some snowflakes mixed in over
the Berkshires this evening.

A Coastal Flood Advisory continues along the coast for low-end minor
flooding potential with the evening high tide, when some erosion and
minor splashover is possible. Fortunately, astronomical tides are on
the lower side, which saves us from much bigger problems that would
have arisen.

&&

.SHORT TERM /FRIDAY NIGHT/...
Friday and Friday night...

Some improvement expected as the low pres slowly lifts north from
the Gulf of Maine, but still chilly and unsettled as mid level low
lingers across northern New Eng with deep moisture in place. Expect
lots of clouds with scattered showers during the day and persisting
into Fri night. While it will be milder on Fri, daytime temps will
remain well below normal in the 50s. Breezy N winds along the
eastern MA coast in the morning then diminishing in the afternoon.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Key Messages:

* Still cool with a few scattered showers Saturday.

* Warmer temps and dry weather will mean Memorial Day is good for
  outdoor activities.

* Wet weather returns around mid-week but timing details uncertain.

A slow but steady improvement in our weather conditions continues on
Saturday and through the holiday weekend as Thursday`s storm slowly
moves away, into the Canadian maritimes by Saturday. This places
southern New England in cool northwest flow while the trough lingers
in our vicinity. This upper level cyclonic flow will result in a
mostly cloudy day (but with breaks of sun, especially later) with
scattered showers. However, not expecting a washout by any means;
simply a cooler day in the low 60s with some passing showers.

Sunday into Memorial Day that improving trend continues as
temperatures climb (upper 60s Sun, low 70s by Mon); however the
trough is very slow to exit so a weak disturbance or two rounding
the broader trough may bring a few widely scattered showers,
especially on Sunday. Even so, most will be dry and we`ll see more
sun. Memorial Day is looking like the pick of the weekend with the
warmest temperatures and least chance of rain as mid level ridging
finally shifts toward the region.

As we move into Tuesday dry weather continues coinciding with the
warmest day in a while as the ridge axis moves overhead. Beyond that
another trough takes aim at the northeast increasing rain chances
for mid week, but confidence in timing and details is low at this
point given model uncertainty.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

00z TAFs: Overall high confidence in trends, but some
uncertainty in timing.

IFR conditions going into tonight. Some embedded TS near the
south coast this evening, especially on Cape Cod and the
Islands. E/NE winds gust to 30kt inland and to 40-45kt along
coast. In addition, LLWS expected near ACK due to 40-50kt winds
at 020.

Slow improvement late tonight into Friday as rain ends from
southwest to northeast, but MVFR/IFR ceilings are likely to
persist.

BOS TAF...High confidence.

BDL TAF...High confidence.

Outlook /Saturday through Tuesday/...

Saturday: Mainly VFR, with local IFR possible. Breezy. Slight
chance SHRA.

Saturday Night through Sunday: Mainly VFR, with local MVFR
possible.

Sunday Night: VFR.

Memorial Day: VFR. Slight chance SHRA.

Monday Night: VFR.

Tuesday: VFR. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Friday night: High confidence.

Peak of the wind will occur through this evening over waters
east of Cape Cod with gusts 35-45 kt, then lifting N over NE MA
waters with NE winds becoming N. Winds gradually diminish
overnight but marginal northerly gales will persist over NE MA
waters through the night. Seas peak at 10-15 ft over eastern MA
outer waters this evening, then slowly subsiding Fri into Fri
night.

A period of heavy rain through this evening with a few t-storms
possible then rain diminishing to scattered showers late
tonight and Fri.

Outlook /Saturday through Tuesday/...

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

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

Sunday through Monday Night: Winds less than 25 kt.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Wind Advisory until 11 PM EDT this evening for MAZ007-015-016-
     019-022>024.
     Coastal Flood Advisory until 11 PM EDT this evening for MAZ007-
     015-016-019-022>024.
RI...None.
MARINE...Gale Warning until 6 AM EDT Friday for ANZ230.
     Gale Warning until 2 AM EDT Friday for ANZ231>237-254>256.
     Gale Warning until 8 AM EDT Friday for ANZ250-251.

&&

$$

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