677
FXUS61 KBOX 031152
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
752 AM EDT Sun May 3 2026

.WHAT HAS CHANGED...
The Small Craft Advisory has been extended until 8pm Monday.

&&

.KEY MESSAGES...

- Lingering showers this morning give way to a slow clearing
  trend this afternoon and tonight.

- Drying trend Monday into Tuesday with warmer temperatures and
  breezy to gusty southwest winds.

- Cold front brings a chance of showers and thunderstorms late
  Tuesday, followed by an unsettled and cooler pattern mid to
  late week.

&&

.DISCUSSION...
KEY MESSAGE 1... Lingering showers this morning give way to a slow
clearing trend this afternoon and tonight.

Expect a few lingering wrap-around showers mainly across eastern
Massachusetts this morning with continued cyclonic flow. Shower
activity wanes by the mid morning as a layer of drier air filters in
at 925 mb. After a brief period of clearing, lingering cyclonic flow
aloft and low-level instability will help form widespread diurnal CU
and stratus clouds. Temperature-wise, not much change in the mid
levels and we`re looking at near persistence if not a few degrees
warmer in valley locations where highs may break into the lower 60s.
Breezy day on tap with model soundings showing a well mixed boundary
layer extending to around 850 millibars paired with a low level
jet that increases to around 25-30 kt.


KEY MESSAGE 2...Turning significantly drier Monday into Tuesday with
warmer temperatures and breezy southwest winds.

The week starts with increasingly zonal flow aloft stemming from the
breakdown of a broad trough over the Eastern CONUS. Further west,
building heights help to develop a Rex block over the Pacific
Northwest serving to re-amplify the upper air pattern. Closer to the
surface, low pressure deepens over the Canadian Maritimes
Monday while high pressure builds to our south over the
southwestern Atlantic resulting in an increasing pressure
gradient. In terms of sensible weather, expect mainly dry
conditions with increasing sunshine and a marked warming trend.
Southwest flow will advect milder air into the region, with
850mb temperatures rising from around +4C to +6C Monday to +12C
to +14C Tuesday. Forecast soundings support a well-mixed
boundary layer, expecting highs in the mid 60s to lower 70s
Monday and upper 70s to low 80s Tuesday. The pressure gradient
tightens through the period, resulting in breezy conditions
Monday with southwest gusts 20-30 mph, increasing to 25-35 mph
Tuesday. One final note, dew points fall into the 20s and 30s
Monday and 30s and 40s Tuesday. These values in combination with
much warmer temperatures will result in relative humidity
values falling to 25-35% Monday afternoon and 30-40% Tuesday
afternoon. This combination will mean fire weather concerns are
possible. Coordination with state fire weather partners is
ongoing, and headlines may be needed early next week.

KEY MESSAGE 3...Cold front brings a chance of showers and
thunderstorms late Tuesday, followed by an unsettled and cooler
pattern mid to late week.

Cold front approaches late Tuesday, though timing remains uncertain.
With highs climbing well above normal, guidance suggests some
instability with up to 1000 J/kg of CAPE, mainly across NW
Mass, which may support scattered convective showers and
thunderstorms. Latest CSU-ML guidance still paints the northern
border of our CWA with low-end (~5%) severe probabilities. This
will need to be monitored give a strengthening low- level jet
in the vicinity. The limiting factor will be moisture with
dewpoints in the lower to mid 50s Tuesday afternoon. The front
may be slow to clear the region, sagging south of southern New
England Wednesday with lingering showers and possible
thunderstorms.

Looking ahead, the pattern becomes more active as mid-level ridge
develops across western CONUS, replacing the Rex blocking, and a
trough across the eastern CONUS. This will support multiple
shortwaves and surface lows moving through the flow, resulting in
periodic chances for showers Thursday into Friday. Timing details
remain uncertain at this range. Late week bears watching, as
guidance suggests a stronger system could impact the region Thursday
night into Friday, accompanied by a robust southerly low-level jet.
This may bring a period of heavier rainfall and gusty winds. While
details remain uncertain this far out, the potential exists for
impactful conditions including hazardous marine weather.
Astronomical tides appear relatively low late week, which should
limit coastal flood potential unless a stronger system materializes.

Behind the front, cooler temperatures return with highs generally in
the upper 50s to lower 60s Wednesday and beyond.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

18z Update:

Today: High confidence.

VFR for most terminals this morning, leaning low-end VFR this
morning as some isolated showers push across from west to east
by early afternoon. Can`t rule out brief MVFR if showers end up
higher in coverage. MVFR/IFR for outer Cape this AM. Ceilings
improve to solid VFR 15-17Z as any isolated showers/moisture
exit. Gusty NW winds 10-15 kts with gusts to 20-25 kts. Gusts
decrease after 00Z.

Tonight: High confidence.

VFR. WNW slowly shifting SW by early Monday morning at 5-10 kts.

Monday: High confidence.

VFR. Gusty SW winds 10-15 kts with gusts 20-25 kts.


KBOS Terminal...Moderate to high confidence in TAF. There is
still a possible window for lowered ceilings between through 15z
as isolated showers move through. Low end VFR to brief MVFR
possible in that window. Ceilings VFR after 15Z with NW gusts
20-25 kts.

KBDL Terminal...High confidence in TAF.

Outlook /Monday Night through Thursday/...

Monday Night through Tuesday: VFR. Breezy.

Tuesday Night: VFR. Breezy. Slight chance SHRA.

Wednesday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA.

Wednesday Night: Mainly VFR, with local IFR possible. Breezy.
SHRA likely.

Thursday: Mainly MVFR, with local VFR possible. Breezy. SHRA
likely.

&&

.MARINE...
Forecaster Confidence Levels...

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

Overall high confidence.

NW winds increase this afternoon with some gusts to 25kts
thru Monday evening. Will also see seas build to 4-6 feet across
the outer waters this afternoon thru Monday. Given these
conditions, the Small Craft Advisory goes into effect at 11am
this morning and has been extended until 8pm Monday. Further
extensions to the SCA will likely be needed with future
forecast updates.

Outlook /Monday Night through Thursday/...

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

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas.

Tuesday Night: Strong winds with gusts up to 30 kt. Areas of
rough seas.

Wednesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Chance of rain showers.

Wednesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Local rough seas. Rain showers likely.

Thursday: Winds less than 25 kt. Local rough seas. Rain showers
likely.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM this morning to 8 PM EDT
     Monday for ANZ250-254>256.

&&

$$

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