BOX issues Area Forecast Discussion (AFD) at Oct 17, 7:37 AM EDT
026
FXUS61 KBOX 171137
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
737 AM EDT Sat Oct 17 2026
.WHAT HAS CHANGED...
Increased probabilities for gale-force gusts in the
Monday-Wednesday timeframe.
&&
.KEY MESSAGES...
- Lingering showers this morning towards the southern coast,
Cape Cod, and the Islands. Otherwise, drier and colder today.
- Dry with a modest warmup through mid next week, but monitoring
stormy conditions near or south of the mid-Atlantic waters
which could bring periods of light rain, enhanced northeast
winds, and building waves/possible erosion to southeast New
England.
&&
.DISCUSSION...
KEY MESSAGE 1...Lingering showers this morning towards the
southern coast, Cape Cod, and the Islands. Otherwise, drier
and colder today.
Showers over much of SE MA and RI continue this morning with the
cold front associated with a low pressure system now over New
Brunswick, Canada draped over the southern portion of the south
shore down into coastal RI. This front will continue eastward
early this morning, and we will find ourselves in a much colder
and drier airmass with high pressure starting to build in from
the west. These showers should remain generally over SE MA, Cape
Cod, the Islands, and parts of RI this morning, then drop off
more towards the afternoon as the drier air behind this front
really sets in. Skies will clear more towards the evening,
especially with high pressure taking more of a hold overhead by
then. Gusty NW winds today as strong cold air advection develops
and the gradient between the exiting low pressure to our
northeast and the high pressure to our west tightens, which may
reach up to 35 mph in some areas this afternoon. 925 mb
temperatures fall below 0C by this evening, and prior to that
mark, they look to hover just above it. Highs today will likely
struggle to reach the low 50s across the interior and lows
Saturday night will likely dip below freezing across the region,
with the exceptions being areas closest to the coasts and urban
areas. Once the gusty NW winds diminish later this evening, we
could see some radiational cooling develop as high pressure
builds in post-FROPA, enhancing an already relatively cold night
for some locations. Areas of frost/freezing conditions are
anticipated, though because our program came to an end on
October 11, there will be no Frost/Freeze headlines issued.
KEY MESSAGE 2...Dry with a modest warmup through mid next week,
but monitoring stormy conditions near or south of the mid-
Atlantic waters which could bring periods of light rain,
enhanced northeast winds, and building waves/possible erosion
to southeast New England.
High pressure continues to build in Sunday and the colder
airmass shifts out of the region. The tighter gradient between
the strong exiting low and approaching high pressure slackens,
which will allow winds to continue diminishing as well. As high
pressure settles in overhead, temperatures will moderate back to
more typical levels for this time of year as 850 mb
temperatures improve from -5C today to around +5C by Sunday
evening. 925 mb temperatures steadily increase as well, reaching
around +10C towards the Monday/Tuesday timeframe. Highs return
to the 50s and 60s into early next week.
One thing we will be keeping an eye on, though, is the
development of low pressure towards the mid-Atlantic/Carolina
coastal waters Sunday into Monday. This feature appears to have
detached from the broader upper level trough that was associated
with the strong low pressure that brought yesterday's
precipitation. Guidance is indicating that a weaker spot in the
surface ridge over southern New England may allow for some
showers to sneak in sometime Monday/Tuesday over southeastern
New England. Given the dry conditions preceding these possible
showers, QPF looks quite limited, with ensemble probabilities
for any measurable rainfall mostly between 10-50%, with the GEFS
and Canadian ENS skewing slightly higher over the Cape and
Islands at 50-60%. The ECMWF ensemble is the lowest of the
three, with the highest probabilities over land being 10-30%.
However, marine impacts with this disturbance are looking a bit
more impactful as it stays relatively stationary and churns over
the same waters for an extended period of time, which will help
build seas up to 15 ft offshore of Nantucket.
The gradient between this area of low pressure and the
preexisting high pressure over southern New England will tighten
greatly, increasing ENE winds over the waters and towards the
Cape and Islands, RI, and the coastal plain in SE MA. Ensembles
have continued to indicate decent probabilities of sustained
winds reaching gale-force over the southern waters, with the
GEFS and Canadian ensemble up to 30-40% (and even up to 60% in
the Canadian guidance) just south of the Islands. In terms of
gale- force gusts, probabilities have increased further from the
last update, reaching the high (80-100%) range in the ECMWF
ensemble and up to 80% in the GEFS. Persistent easterly fetch
associated with these winds, along with building rough seas,
will need to be monitored as well, as beach erosion for east-
and northeast- facing beaches may become an issue.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Today: High confidence in TAF/trends, but moderate on when SHRA
clears southeast New England.
VFR, but rain showers could linger until early afternoon for PVD,
and potentially into mid afternoon for the Cape and Islands.
North and west from there, VFR prevails. Gusty NW winds around
13-17 kt with gusts 25-30 kt.
Tonight: High confidence.
VFR. Easing NW to N winds to around 5-10 kt by midnight,
continuing to ease to light NW overnight.
Sunday: High confidence.
VFR. Light N winds, though becoming NE around 8-12 kt for the
Cape and Islands.
KBOS Terminal...Moderate confidence in TAF. Timing of showers
could be slightly later than the TEMPO, though should not vary
too much from those hours.
KBDL Terminal...High confidence in TAF.
Outlook /Sunday Night through Wednesday/...
Sunday Night: VFR.
Monday: VFR. Breezy.
Monday Night: Mainly VFR, with local MVFR possible. Breezy.
Tuesday: VFR. Breezy.
Tuesday Night: VFR. Windy with areas of gusts up to 30 kt.
Wednesday: VFR. Windy with gusts up to 30 kt.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Through Sunday...Moderate confidence.
Gusty NW winds today following an overnight cold front.
Uncertainty remains regarding the potential for gale-force wind
gusts over the ocean zones for tonight, which currently are
forecast to remain just under gale-force. Latest guidance has
trended winds aloft tonight to generally in the mid-20 kt range
up to the 850 mb mark, which would very much keep winds below
gale criteria. Seas remain generally within Small Craft Advisory
levels for the coastal and outer waters, though seas build to
around 8 ft by Sunday in the ocean zones after the other waters
briefly fall back to around 4 ft at most. Winds diminish greatly
Sunday, sustained up to 15 kt over the southern waters and up
to 10 kt over the eastern/NE waters. Gusts remain generally
below 20 kt Sunday.
Outlook /Sunday Night through Wednesday/...
Sunday Night: Winds less than 25 kt. Rough seas up to 15 ft.
Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 16 ft. Chance of rain showers.
Monday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 15 ft. Chance of rain
showers.
Tuesday: Strong winds with gusts up to 35 kt. Rough seas up to
12 ft. Chance of rain showers.
Tuesday Night: Strong winds with gusts up to 40 kt. Rough seas
up to 12 ft. Slight chance of rain showers.
Wednesday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 12 ft. Slight chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230-
236.
Small Craft Advisory until 2 AM EDT Sunday for ANZ231-251.
Small Craft Advisory until 8 AM EDT Sunday for ANZ232>235-237-
250.
Small Craft Advisory until 11 AM EDT Sunday for ANZ254>256.
Gale Watch from this evening through Sunday morning for
ANZ281>283.
&&
$$
DISCUSSION...Hrencecin
AVIATION...Belk/Loconto/Hrencecin
MARINE...Hrencecin
Source: BOX issues Area Forecast Discussion (AFD) at Oct 17, 7:37 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202610171137-KBOX-FXUS61-AFDBOX)
----------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!