National Weather Service Forecast for: Mashpee MA Issued by: National Weather Service Norton, MA

Updated: 7:15 pm EDT May 20, 2025

Mashpee, MA

Overnight Low: 45 °F Wednesday High: 52 °F Wednesday Night Low: 48 °F Thursday High: 56 °F Thursday Night Low: 48 °F Friday High: 58 °F Friday Night Low: 49 °F Saturday High: 60 °F Saturday Night Low: 49 °F Cloudy Cloudy then Slight Chance Showers Chance Showers Heavy Rain and Breezy Rain then Rain Likely Chance Rain Mostly Cloudy then Chance Showers Chance Showers Mostly Cloudy

Forecast from NOAA-NWS for Mashpee MA.

008
FXUS61 KBOX 202328
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
728 PM EDT Tue May 20 2025

.SYNOPSIS...
Cloudy with unseasonably cool high temperatures for the remainder of
the work week that will run 10 to 20 degrees below normal. A
late season Nor`eater will bring a cold windswept heavy rain to
the region late Wednesday into early Friday. The brunt of this
storm appears to be Thursday, when wind gusts of 40-50+ mph will
be possible along the coast with pockets of minor coastal
flooding also possible. The soaking rain will likely come to an
end Friday morning, but a few showers will remain possible
Friday afternoon into Saturday. Temperatures will slowly
moderate, but still remain below normal into this weekend.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...

Key Messages...

* Cloudy & cool tonight with dry weather other than a few spotty
  sprinkles/light showers with lows in the 40s to near 50

Persistence forecast into tonight with ridging overhead and
cool, moist low level onshore flow will result in cloudy skies.
Mainly dry weather will prevail...but a few sprinkles/light
showers possible at times. Greatest risk for these will be along
the east slopes of both the Worcester Hills/Berks with upslope
flow. Overnight low temps should be in the 40s to near 50

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...

Key Messages...

* Temps a bit cooler than Tuesday, with clouds and patchy drizzle.

* Rain moves in late Wednesday night.

More of the same weather expected on Wednesday, except even a bit
colder and with even less breaks of sun. This is due to continued
low level moisture/clouds moving from northeast to southwest off the
ocean as well as mid/upper level moisture/clouds moving in from
southwest to northeast ahead of the approaching frontal system. Cold
advection continues on northeast flow in the low levels, with 925 mb
temps dropping from 5-6C Tuesday to 1-2C Wednesday. This will lead
to high temperatures in the low to mid 50s for most; locations in
the CT Valley will benefit from some downslope flow and may reach
60.

A cold, windswept rain arrives Wednesday night ahead of a late
season nor`easter. The parent low over the Ohio Valley Wednesday
will generate a secondary coastal low along the frontal boundary
Wednesday night moving off the mid Atlantic coast into Thursday. The
plume of moisture ahead of the system together with a 25-35kt LLJ
will generate a precip shield slowly expanding into most of SNE by
8am. As the pressure gradient tightens we`ll also see winds at the
surface become increasingly gusty toward sunrise, gusting 20-30 mph
but the bulk of the rain and wind arrive later Thursday.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...

Key Messages...

* Late season Nor`easter Thu into early Fri brings 1-2" of rain with
  localized 3" amounts along with poor drainage street flooding

* ENE wind gusts of 40-50+ mph possible along the coast Thu with
  perhaps some pockets of minor coastal flooding during high tide

* A few showers will remain possible Fri into Sat but these will be
  hit or miss...followed may mainly dry weather Sun and Mon

* Unseasonably chilly temps Thu gradually moderate through the
  Holiday Weekend, but we probably do not break 70 until Memorial Day

Details...

The main forecast concerns continues to be the late season
Nor`easter which will bring windswept heavy rain to the region Thu
into early Fri. The other concerns revolve around the potential for
strong winds along the coast along with pockets of minor coastal
flooding possible. We will break it down more below.

1) Heavy Rain 1-2" with localized 3" amounts late Wed into early Fri

The latest 12z guidance continues to be in good agreement in
intensifying low pressure system that will pass inside the Benchmark
Thu into early Fri. This will combined with a modest high pressure
system in the Maritimes to result in an anomalously strong easterly
LLJ. The 850 mb LLJ is 3+ standard deviations outside climatology
for this time of year. In addition...a closed 700 mb low will lift
across southern New England resulting in a mid level deformation
zone. Putting all these ingredients together...the stage is set for
a widespread heavy rain event. We are thinking 1-2" of rain are in
store for much of the region...but some localized 3" amounts are
possible especially near any coastal front or mid level deformation
axis. This may result in some poor drainage street flooding
especially in some of those typically prone urban locations.
However...not expecting any serious type flash flooding.

In addition...high temperatures on Thursday will be running 20 to 25
degrees below normal for this time of year. Near record low high
temperatures in the 45 to 55 degree range are expected. It will feel
even chillier with the wind.

2) Period of easterly wind gusts of 40-50+ mph along the coast

The other issue will be a period of easterly wind gusts of 40-50+
mph along the coast that will be associated with the anomalously
strong easterly LLJ. The 850 mb jet is expected to increase to
between 50 and 60 knots that will be pointed toward the coast.
Thinking that we will need some wind headlines across the Cape and
Islands and perhaps all the way up the eastern MA coast. Given this
is a 4th period event will not issue with this package...but we
probably will need to issue in the next 24 hours.

3) Potential for minor coastal flooding with the Thu PM high tide

The anomalously strong easterly low level flow will help to build
seas to 10-15+ feet offshore. Astronomical high tides are not that
high with Boston at 10.0 MLLW Thu evening. However...appears that a
1.5 to 2.5 foot storm surge off the coast with rather high seas off
the coast will bring the potential for pockets of minor coastal
flooding during the Thu evening high tide cycle along the eastern MA
coast/Nantucket. A coastal flood advisory may eventually be needed
for this region in later forecasts.

Friday afternoon through the Holiday Weekend...

After the steady rain departs Fri morning...a few showers will
remain possible at times Fri afternoon into Sat but a washout is not
expected. A lot of these scattered showers will be diurnally driven
with anomalous shortwave energy/cold pool aloft overhead. This
anomalous upper level trough begins to shift to the northeast Sun
and Memorial Day...which should bring mainly dry weather.

Temperatures will be slow to moderate through the Holiday Weekend,
but they will gradually as the trough begins to push east of the
region. Highs in the 50s to near 60 in spots Fri and probably into
the 60s in most locations by Sat and especially Sun. Appears we
finally may break 70 in spots by Memorial Day.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...

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

00z TAF Update...

Tonight and Wednesday: High confidence.

Widespread MVFR cloud bases with little change. NE winds around
5-10 kt tonight, which then increase to around 10-15 kt with
gusts to 20+ kt.

Wednesday Night: Moderate confidence.

MVFR-IFR with increasing rain chances as heavier precipitation
moves in from the southwest. E/ENE winds 10-20 kts, increasing
toward 12Z.

BOS TAF...High Confidence in TAF.

BDL TAF...High Confidence in TAF.

Outlook /Thursday through Sunday/...

Thursday: Mainly IFR, with local MVFR possible. Strong winds
with gusts up to 40 kt. RA.

Thursday Night: Mainly IFR, with areas MVFR possible. Windy
with gusts up to 35 kt. RA likely.

Friday: Mainly MVFR, with local IFR possible. Windy with local
gusts up to 30 kt. Chance SHRA.

Friday Night: Mainly MVFR, with local IFR possible. Chance
SHRA.

Saturday: MVFR. Breezy. Chance SHRA.

Saturday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.

Sunday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today Through Wednesday night: High confidence.

NE winds 5-10 kt this afternoon and tonight, increasing to
10-15 kt with gusts 20-25 kt Wed. Seas may still be near 5 ft in
southeast waters today through Wed night.

Outlook /Thursday through Sunday/...

Thursday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 11 ft. Rain. Visibility 1 to 3 nm.

Thursday Night: Low risk for gale force winds with gusts up to
40 kt. Rough seas up to 13 ft. Chance of rain.

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 11 ft. Chance of rain showers.

Friday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers.

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

Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Watch from Thursday morning through late Thursday night
     for ANZ230-236.
     Gale Watch from late Wednesday night through late Thursday
     night for ANZ231>235-237-254>256.
     Small Craft Advisory until 8 AM EDT Wednesday for ANZ250-254-
     255.
     Gale Watch from late Wednesday night through late Thursday
     night for ANZ250-251.

&&

$$

SYNOPSIS...BW/Frank
NEAR TERM...Frank/BW
SHORT TERM...BW
LONG TERM...Frank
AVIATION...BW/Frank
MARINE...BW/Frank

NWS BOX Office Area Forecast Discussion