375
FXUS61 KBOX 032317
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
717 PM EDT Sun May 3 2026

.WHAT HAS CHANGED...
The Small Craft Advisory has been expanded into the inner waters
on Monday and an SPS has been issued for elevated fire weather
potential on Monday for all of Southern New England except for
Cape Cod and the islands. Wind gusts have been increased during
the afternoon hours into mid- week.

&&

.KEY MESSAGES...

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

- Mainly dry, windy & unseasonably warm away from the south coast
  Tue. Low risk for iso t-storms late across northwest MA.

- Periods of showers arrive from west to east Wed and may persist
  into Thu/Thu night...But that is more uncertain and dependent on a
  secondary wave of low pressure.

- Near/slightly below normal temps Fri into next weekend with
  perhaps a few showers at times...But not a washout.
  Mild days/cool nights with potentially some frost at times.

&&

.DISCUSSION...

KEY MESSAGE 1...Drying trend Monday with warmer temperatures
and breezy to gusty southwest winds.

As expected, despite a mostly dry atmospheric column, stubborn
moisture in the 850mb layer together with the lingering
trough/cyclonic flow aloft have led this morning`s sun to be
replaced by thick diurnal cloudcover. That, combined with some light
rain over the eastern half of the region has led to a cool, raw day.
Things are looking up, though as we head into the next 24-48 hours.
This is thanks to expected rising mid level heights as a ridge of
surface high pressure moves in to replace the offshore low. This
will push temperatures up...flow turns SW and pushes 850mb temps
from 0C to +6C by Monday afternoon. Given the expected well mixed
boundary layer up to 800mb with full sun, expecting high
temperatures to be 10 to 15 degrees warmer than Sunday. The warmest
spots will be the CT valley where downsloping wind helps push temp
into the low 70s while areas along the immediate south coast will be
coolest in the low to mid 60s. This good mixing also leads to a
gusty day; with a 25-35kt 850mb jet overhead, expecting to mix down
gusts of 25 to 35 mph. This, combined with the drier air (RH values
down to 25-30 percent) has led us to issue a Special Weather
Statement for elevated fire weather potential covering all of
southern New England with the exception of Cape Cod and the islands.

KEY MESSAGE 2...Mainly dry, windy & unseasonably warm away from
the south coast Tue. Low risk for iso t-storms late across
northwest MA.

A cold front slowly pushes into the eastern Great Lakes will
combined with high pressure moving further east out in the Atlantic
on Tue. The result will be a gusty SW winds and unseasonably warm
temperatures away from the marine modified airmass towards the south
coast. 925T on the order of +17C/+18C should allow highs to reach
near 80 in the lower elevations northwest of I-95. The gusty
southwest winds will hold highs in the 60s near the south coast,
Cape and Islands. It is possible that Nantucket does not even break
60 degrees! Bufkit soundings support southwest wind gusts of 25 to
35 mph with a few gusts of 40-45 mph possible towards the upper Cape.

Mainly dry weather prevails Tue as most of the synoptic scale
forcing will remain well to our west in the vicinity of the cold
front. However...low risk enough instability develops for a few late
Tue afternoon/evening showers/t-storms across northwest MA.

KEY MESSAGE 3...Periods of showers arrive from west to east Wed
and may persist into Thu/Thu night...But that is more uncertain
and dependent on a secondary wave of low pressure.

A slow moving cold front approaches the region from the west on Wed.
Still some timing differences...But we do expect a band of showers
to overspread the region from west to east as the day wears along.
This may take until mid-late afternoon to reach the I-95
corridor...but again the timing still needs to be worked out. There
might be an embedded t-storm or two as well...But instability does
not look to be high enough for any severe weather.

This cold front slowly sags south of our region Wed night into Thu
bringing cooler temps. We will then need to watch for a secondary
wave of low pressure that may bring more rain to parts of the region
sometime Thu into Thu night...But that remains uncertain. The GFS is
quickest with this secondary wave and also furthest
north...bringing a soaking rain to the region Thu. Meanwhile...the
Canadian/ECMWF are further south showing the best chance for another
period of steady rain will not be until later Thu into Thu night and
that may be just a glancing blow across parts of RI/SE MA. This will
need to be sorted out once the guidance comes into better agreement.
This will also have a significant impact on temperatures during the
day Thu depending on if we see rain or end up mainly dry.

KEY MESSAGE 4...Near/slightly below normal temps Fri into next
weekend with perhaps a few showers at times...But not a washout.
Mild days/cool nights with potentially some frost at times.

The long range ensembles are in good agreement in an upper trough
with below normal height fields re-establishing itself Fri into the
weekend. Modest westerly flow this time of year coupled with the
strong May sun angle should keep high temps near or just slightly
below normal though. Highs should still mainly be in the 60s. The
night/s will be potentially cool though with lows in the 40s and
potentially some 30s along with a frost risk if we have enough
clearing.

As for precipitation chances...some shortwave energy with the
associated upper trough/cold pool aloft may bring the potential for
a few showers at times. However...not expecting a washout with
plenty of dry weather expected as well over this time.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...

Forecaster Confidence Levels...

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

00z TAF Update...

VFR conditions continue tonight through Monday night. Gusty WNW
quickly diminish after sunset and become light from a SW/WSW
direction overnight. SW winds increase later Mon morning and
especially in the afternoon with gusts on the order of 25 to 35
knots with perhaps a few gusts near 40 knots towards the
typically prone locations near KFMH. The gusts gradually
diminish Mon evening...but still expect sustained S-SW winds of
5 to 15 knots overnight with a few gusts up to 20 knots
persisting.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday through Friday/...

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.

Thursday Night: VFR. Breezy. Chance SHRA.

Friday: VFR. Breezy. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

High confidence.

Through Monday night...

NW winds gust to 25kts today, diminishing overnight and
increasing again on Monday out of the SW gusting 25-30 kts.
Will also see seas build to 4-6 feet across the outer waters
thru Monday. Given these conditions, the Small Craft Advisory
has been extended into Monday night for the outer waters and
expanded into the inner waters on Monday.

Outlook /Monday Night through Friday/...

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.

Thursday Night: Winds less than 25 kt. Areas of rough seas.
Chance of rain showers, slight chance of thunderstorms.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas. Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 11 AM to 8 PM EDT Monday for
     ANZ230>237-251.
     Small Craft Advisory until 8 AM EDT Tuesday for ANZ250-254>256.

&&

$$

DISCUSSION...Frank/BW
AVIATION...Frank/BW
MARINE...Frank/BW