BOX issues Area Forecast Discussion (AFD) at Sep 7, 12:57 PM EDT298
FXUS61 KBOX 071657
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1257 PM EDT Mon Sep 7 2026
.WHAT HAS CHANGED...
Updated aviation section for 12Z TAFs.
&&
.KEY MESSAGES...
- Pleasant weather for the Labor Day Holiday with low humidity
and mild temperatures. The dry and pleasant conditions
continue through Wednesday.
- Unsettled weather returns mid to late week but the threat for
flooding and severe weather appear low at this time.
&&
.DISCUSSION...
KEY MESSAGE 1...Pleasant weather for the Labor Day
Holiday with low humidity and mild temperatures. Dangerous rip
currents continue at east-facing beaches through most of the
day. The dry and pleasant conditions continue through
Wednesday.
4am Update: Went ahead and issued a Rip Current Statement for
east-facing beaches as well as the islands. Numerous off and
near-shore buoys are still reporting elevated wave periods of
8-10 seconds, which is favorable for the formation of rip
currents and locally hazardous swimming conditions.
A tranquil Labor Day Holiday is on tap as high pressure builds over
the Northeast. Aloft, these changes are driven by a broad 500 mb
ridge sprawling from the mid south into the Northeast. Looking at a
cool start to the morning after tonight's radiational cooling. The
vast majority of locations will wake up to lows this morning in the
lower to mid 50s with isolated 40s in favored valley locations.
After a cool start, there's a lot to look forward to with regards to
today's sensible weather. Temperature-wise it's a seasonably mild
day with highs warming into the mid and upper 70s. To further
solidify today as a peak weather day humidity levels will certainly
be fall-like with dew points in the 40s and low 50s. Only caveat
will be a somewhat gusty NW wind. A modest low-level jet of 25-30kts
combined with a well-mixed boundary layer will yield gusts up to 20
mph. On Tuesday, the deeper mid-level trough continues to shift
further eastward as a mid-level ridge continues to build in from the
west. 925mb temperatures warm to +17-18C yielding high temperatures
in the upper 70s with locations potentially hitting the 80 degree
mark in the valleys. High pressure in place will support mainly dry
conditions.
KEY MESSAGE 2...Unsettled weather returns mid to late week but the
threat for flooding and severe weather appear low at this time.
By Wednesday, the mid-level ridge begins to break down and the
pattern becomes more more zonal by Thursday. Guidance continues
to show a series of shortwaves and low pressure systems passing
N of the region with their associated frontal boundaries
bringing chances for precipitation during the second half of
the week. Any boundaries that pass through the region will be
accompanied by a plume of above normal moisture, rising to
160-190% of normal by early Thursday yielding PWATS of 1.5"
approaching 2.0". The positioning of an upper jet should supply
ascent for periods of showers. There is spread across guidance
in the finer details of the timing of the waves which will
influence timing of the showers. A shortwave pushes through
sometime Wednesday evening/night triggering the first round of
showers which should taper off through the morning Thursday (at
latest). The next wave moves through late Thursday/Thursday
Night bringing another round of showers. With the timing of the
waves still variable across guidance this leaves some
uncertainty in thunderstorm/downpour potential. There will be
plenty of moisture to support downpours; however, the timing of
the wave would need be early enough to tap into the marginal
instability build through the day for convection. For now, we
are not seeing a strong signal for severe or flash flooding,
more likely periods of showers with light accumulations outside
of any isolated storms/downpours. An 850mb 35- 45kt LLJ shifts
across southern New England into Thursday. There does raise a
flag for potentially gustier winds; however, this will come down
to how well we can mix down from 850mb or even 925mb. If things
align, ensembles show potential for gusts in the 20-35 mph
range on Thursday across the land and coastal waters. Still
plenty of details to work out in the pattern before we come into
better agreement about the gusts, but something to watch for
now.
Temperatures Wednesday/Thursday lean near to slightly above normal
with temperatures in the mid to upper 70s. A cold front pushes
through early Friday bringing a cooler airmass this will support
highs in the upper 60s low 70s.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18z TAF Update...
This afternoon and Tonight...High confidence.
VFR. NW winds 10-15 kt with gusts up to 20 kt. Winds diminish
this evening between 22-00z and become more WNW overnight.
Tuesday...High confidence.
VFR. NW winds around 5-10 kt. Chance for localized seabreezes
towards the late afternoon hours around 20-21z. Will continue
to monitor.
Tuesday night...High confidence.
VFR. Winds calm.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF.
Outlook /Tuesday Night through Saturday/...
Tuesday Night: VFR.
Wednesday: VFR. Breezy.
Wednesday Night: VFR. Windy with local gusts up to 30 kt.
Chance SHRA.
Thursday: VFR. Windy with areas of gusts up to 30 kt. Chance
SHRA, slight chance TSRA.
Thursday Night: Mainly VFR, with local IFR possible. Breezy.
Slight chance SHRA.
Friday: VFR.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Through Tuesday: High confidence.
Generally light northerly winds this morning pick back up again
today to around 15-20 kt, then subside overnight. Seas will
continue to decrease to 3 ft or less through the day today.
Lighter W winds Tuesday decrease to 10-15 kt with similar wave
heights of 2-3 feet.
Outlook /Tuesday Night through Saturday/...
Tuesday Night through Wednesday: Winds less than 25 kt.
Wednesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Local rough seas. Chance of rain
showers.
Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 9 ft. Slight chance of rain
showers.
Thursday Night: Winds less than 25 kt. Areas of rough seas.
Chance of rain showers, slight chance of thunderstorms.
Friday: Winds less than 25 kt. Seas up to 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents until 8 PM EDT this evening for MAZ007-
014-015-019-022>024.
RI...None.
MARINE...None.
&&
$$
DISCUSSION...Mensch/FT
AVIATION...BW/FT
MARINE...Mensch/FT
Source:
BOX issues Area Forecast Discussion (AFD) at Sep 7, 12:57 PM EDT----------------
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