874
FXUS61 KBOX 021202
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
802 AM EDT Sat May 2 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Areas of light rain showers this morning with another round developing
  this afternoon. More widespread rain arrives for the Cape and
  Islands tonight.

- Turning drier and sunnier with a warming trend Monday and Tuesday.

- Increasing chance for showers and even thunderstorms mid to late
  week.

&&

.DISCUSSION...
KEY MESSAGE 1... Areas of light rain showers this morning with
another round developing this afternoon. More widespread rain
arrives for the Cape and Islands tonight.

Shortwave impulse provides enough lift for a round of scattered
showers early this morning across much of northern and central
Massachusetts. After a bit of a lull in the morning, the chance for
showers increases again this afternoon as a weak surface boundary
moves from west to east. CAMs show about 150-300 J/kg of surface
CAPE and low level lapse rates steepening to 8-9 C/km, sufficient
values for another wave scattered showers and perhaps a rumble of
thunder or two.

Attention turns to a sub-990 mb cyclone as it takes a track NE to a
path east of the 40N/70W benchmark for late this afternoon and
continuing northward into Sunday. There will be a sharp gradient on
the northwestern edge of the precip shield as drier air behind a
weak front makes its way into interior southern New England. The
latest NBM still has the western edge of steadier rains across the
MA/RI coastal plain to around I-495, where the GEFS and EPS
ensembles have a 60-80 percent chance of at least a half inch of
rain.

All told, not really a great weekend if your plans bring you to Cape
Cod or eastern MA and RI, but conditions in CT and western MA should
be quite a bit better. Highs mainly in the 50s on Saturday with
clouds and periods of showers, cooler lower 50s in southeast New
England; on Sunday, highs have a decent shot at reaching the low 60s
in western interior Southern New England, but are in the mid 50s
near the eastern coast as it will take quite a bit longer before we
can see peeks of sun develop.

KEY MESSAGE 2...Turning drier and sunnier with a warming trend
Monday and Tuesday.

Southwesterly flow advects a much warmer airmass in from the Mid
Atlantic Monday and Tuesday. 850 mb temperatures climb to +5C Monday
and then +12-14C Tuesday. These values bring highs in the 60s to
lower 70s on Monday, but diurnal mixing of lower dewpoints (RHs down
to around 30 percent) to go along with breezy southwest winds could
warrant fire weather concerns on Monday. Temperatures on Tuesday are
even warmer with most areas away from the southeast coast well into
the 70s, except SW winds look to be a little lighter and relative
humidities aren`t quite as low. Will assess how much rain actually
falls and then consider fire weather partner input before weighing a
decision on fire weather headlines, but they could be possible on
Monday and possibly Tuesday.

KEY MESSAGE 3...Increasing chance for showers and even thunderstorms
mid to late week.

500 mb pattern amplifies by midweek, with a pronounced upper trough
over the nation`s midsection and an amplifying ridge associated with
above normal temperatures over the eastern and southeast US into the
western Atlantic. A slow-moving frontal boundary will be progressing
eastward with low pressure developing along it at some point late in
the week - guidance varies on when this happens but loose consensus
around Thursday. Pretty robust dynamics and decent moisture plume
could favor several opportunities for showers and even a few
thunderstorms around late in the week. We do need the rain so this
should be more beneficial than necessarily hazardous, but either
way, expect temperatures to remain slightly above normal but with
chances for rain on the increase. Will have to watch this boundary
for the development of a more significant low pressure by weeks end
but details are unclear at this time.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

12Z Update

Today: Moderate confidence on the timing and coverage of -SHRA.

Low-end VFR/MVFR ceilings with passing -SHRA over interior
CT/western into northeast MA advancing east to BOS between
14-16Z. Better chance for 4-6 SM -RA and MVFR ceilings comes in
after 21z for Cape/Island terminals as coastal low pressure
begins to approach. -SHRA continues through early evening for
BOS while RA continues for the south coast and southeast MA. S
winds become SE/ESE this afternoon for eastern airports around
5-10 kts.

Tonight: Moderate confidence.

VFR from ORH westward. MVFR ceilings for southeast MA terminals
including Cape and Islands. Steadier RA continues in the
southeast including ACK, HYA, FMH, and potentially PVD. Can`t
rule out a passing shower for BOS. Winds come around to NW 5-10
kts.

Sunday: High confidence.

MVFR, at least for east terminals early Sunday AM. Improving to
VFR mid morning and closer to early afternoon for Cape/Island
terminals. VFR for west/central terminals. NW winds 8-12 kts
with a few gusts to 20 kts.


KBOS Terminal...High confidence in TAF.
Winds to go light later in the day (after 19Z), which could
allow for a period of light onshore winds to develop before
becoming S around 5 kt. Otherwise expect a few passing showers
early this morning with scattered showers shifting across BOS
later in the morning continuing through early evening. A few
showers are possible overnight depending on the track of an
offshore surface low pressure system.

KBDL Terminal...High confidence in TAF.

Outlook /Sunday Night through Wednesday/...

Sunday Night: VFR.

Monday through Tuesday: VFR. Breezy.

Tuesday Night: VFR. Windy with gusts up to 30 kt. Slight chance
SHRA.

Wednesday: VFR. Windy with gusts up to 30 kt. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Overall high confidence.

Winds and seas should remain below small craft advisory levels
through today and tonight. Winds increase to 10-15 kt this
afternoon, with seas 4 ft or less all waters. Mainly dry
weather, though rain begins to increase on the southern waters
later tonight into Sunday.

Winds and seas then increase to small craft levels late Sunday
morning as winds turn NW with gusts 20-25 kt and seas building
to 4-6 ft on the outer waters. Rain could also locally reduce
visibility.

Outlook /Sunday Night through Wednesday/...

Sunday Night: Winds less than 25 kt. Local rough seas.

Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft.

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

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.

Tuesday Night: Strong winds with gusts up to 35 kt. Local rough
seas.

Wednesday: Strong winds with gusts up to 35 kt. Seas up to
5 ft. Chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM Sunday to 2 PM EDT Monday for
     ANZ250-254>256.

&&

$$

DISCUSSION...FT
AVIATION...Mensch/FT
MARINE...FT