Plymouth, Massachusetts 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

684
FXUS61 KBOX 271722
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
122 PM EDT Sun Jul 27 2025

.SYNOPSIS...
Scattered showers will remain possible into early this evening.
Otherwise...the main story will be the return of the dangerous
heat and humidity Monday through Wednesday and Heat Advisories
have been posted for much of the region. A cold front may bring
some scattered showers and thunderstorms sometime Wednesday
and/or Thursday...followed by much cooler/less humid weather
which will persist into next weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages...

* Scattered hit or miss showers at times into this evening with an
  isolated t-storm or two possible

* Areas of fog develop tonight and may become locally dense in the
  typically prone spots...lows in the middle 60s to the lower 70s

Details...

Into Tonight...

The steadiest of the showers have now moved into northeast MA as of
early afternoon. We expect this activity to depart over the next 1-2
hours as the initial shortwave departs. However...diurnal
destabilization was allowing scattered showers and thunderstorms to
develop across parts of NY/PA. Modest west to northwest flow aloft
will bring the potential for additional scattered showers this
afternoon into early this evening...but these will be hit or miss
with plenty of dry weather in between. Instability will also be more
limited in our region given the cloud cover...so even if we see an
isolated t-storm or two not expecting severe weather.

Otherwise...drier mid level air will work into the region tonight.
This will allow for some partial clearing to occur...but the low
levels will remain moist with light/calm winds. This will lead to
the formation of fog...some of which may become locally dense in the
typically prone spots. Overnight low temps should bottom out in the
middle 60s to the lower 70s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Key Messages...

* Sunshine along with the heat & humidity return on Mon
* Highs Mon lower-middle 90s for many away from the immediate coast
* Heat Indices Mon in the middle to upper 90s

Details...

Monday...

Dry NW flow aloft and at the surface will result in plenty of
sunshine for Monday...but also a return of the heat and humidity.
850T moderate to between +17C/+18C and expect a super adiabatic
atmosphere. This should allow highs to reach the lower to middle 90s
in many locales away from parts of the immediate coast. We will mix
some of the dewpoints out given NW flow...but still expect heat
indices to reach the middle to upper 90s. Therefore...Heat
Advisories continue and we opted to expand them to the south coast
where dewpoints will be higher. We also extended the Heat Advisories
through Wednesday...which will be discussed in the long term
section. The weak pressure gradient will allow sea breezes to
develop along portions of the immediate coast and hold highs into
the 80s across this region.

Monday night...

A ridge of high pressure will be in control of our weather Monday
night. This will result in light/calm winds with low temps in the
60s to near 70. We may also see some fog develop again Mon night. We
also will need to watch for some more smoke/haze from distant
Canadian Wildfires based on the HRRR/RAP...but the worst of that may
remain to our north.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Key Messages...

* Above normal temperatures/heat Tue/Wed. Heat Advisory Tuesday.

* Mostly dry this week with a chance of showers and t-storms Wed/Thu.

* Cooler for the second half of the week.

Details...

Ensemble guidance shows anomalous temperatures again for Tuesday and
potentially into Wednesday to some extent as a mid-level ridge
remains over the region. Tuesday will likely be the hottest day
of the week with highs in the low to mid 90s. Had to make some
small adjustments to dewpoints because they were a little too
high. Model soundings show sufficient mixing in the boundary
layer which would likely result in slightly lower dewpoints.
Regardless...it will still be humid with dewpoints around 70F.
This will make it feel more like upper 90s to near 100. A Heat
Advisory will be in effect for both Monday and Tuesday for much
of southern New England except the Cape/Islands and south coast.

Tuesday, a weak shortwave trough moves through the flow aloft which
will bring isolated to scattered showers and thunderstorms in the
afternoon. Ensemble guidance shows a more substantial wave moving
through in the Weds-Thurs timeframe. Still uncertainty in the
details such as timing, precipitation chances/amounts. What makes
this wave also more substantial aside from increased precipitation
chances will be the cooler airmass pushing in behind it. This will
break the above normal temperatures from earlier in the week.
Ensemble guidance shows good agreement with a transition to even
below normal temperatures with highs cooled into the mid 70s to low
80s by Friday.

&&

.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

18z TAF Update...

Through 00Zz...Moderate confidence.

Showers will continue to move through the region. Generally VFR
outside outside of any shower activity with pockets of IFR/LIFR
under heavier elements. Activity tapers after 20z and coverage
will wane after sunset. Temporary improvement to mainly VFR
behind the showers but lingering moisture brings back a chance
for IFR/LIFR after sunset.


Sunday night...Moderate confidence.

Forecast challenge will be ceilings. Ceilings may improve
temporarily to mainly VFR, but in that case may allow low
clouds and fog patches to develop. Areas with the greater risk
will be the Cape/Islands and coastal areas. Not confident enough
to fully message in TAF just yet, but hinted at potential with
FEW/SCT groups of IFR/LIFR conditions. Included FG in a PROB30
group for PVD and Cape/Islands terminals. Light SW winds
becoming NW after 06z.

Monday...High confidence in trends.

Any ceilings developed overnight will scatter out after 12z.
Winds light NW less than 10 kts with sea breezes developing by
the afternoon.

KBOS terminal...Moderate confidence in TAF.

Moderate confidence in timing of the showers this morning. Best
timeframe for seeing showers is 13z-18z, but can`t rule out an
isolated shower just outside that timeframe. Low chance (< 20%)
for an isolated shower/storm after 20z. Ceilings may be tricky
this evening with some model guidance hinting at low ceilings
sneaking into the terminal after 00z. Not confident enough to
include in the TAF yet, but have hinted at it with SCT lower
ceilings.

KBDL terminal...Moderate confidence in TAF.

Moderate confidence with timing of showers as they arrive from
west early this morning. The AM wave of showers should be out by
16z, with perhaps a stray shower or two around. There is a
chance for an isolated shower/storm after 20z at/near the
terminal. Probability (<30%) given isolated nature.

Outlook /Monday Night through Thursday/...

Monday Night: Mainly VFR, with local IFR possible. Patchy BR.

Tuesday through Tuesday Night: VFR.

Wednesday: VFR. Breezy. Slight chance SHRA, slight chance TSRA.

Wednesday Night: VFR. Chance SHRA, chance TSRA.

Thursday: Mainly VFR, with local MVFR possible. Chance SHRA,
chance TSRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight through Monday night...High confidence.

A weak frontal boundary will cross the region tonight. A ridge of
high pressure will then setup to our west Monday into Monday night.
The pressure gradient will remain weak enough to keep winds/seas
below small craft advisory thresholds through Monday night.

Outlook /Monday Night through Thursday/...

Monday Night: Winds less than 25 kt. Patchy fog. Local
visibility 1 nm or less.

Tuesday through Wednesday: Winds less than 25 kt.

Wednesday Night: Winds less than 25 kt. Chance of rain showers,
chance of thunderstorms.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from 11 AM Monday to 8 PM EDT Wednesday for
     CTZ002>004.
MA...Heat Advisory from 11 AM Monday to 8 PM EDT Wednesday for
     MAZ003>007-010>021-026.
RI...Heat Advisory from 11 AM Monday to 8 PM EDT Wednesday for
     RIZ001>007.
MARINE...None.

&&

$$

SYNOPSIS...Mensch
NEAR TERM...Mensch
SHORT TERM...Mensch
LONG TERM...Mensch
AVIATION...FT
MARINE...Mensch