BOX issues Area Forecast Discussion (AFD) at Oct 17, 7:12 PM EDT186
FXUS61 KBOX 172312
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
712 PM EDT Sat Oct 17 2026
.WHAT HAS CHANGED...
Gale Watches issued for our southern waters early next week.
&&
.KEY MESSAGES...
- Diminishing winds and clearing tonight with cold low temps in the
20s and 30s with widespread frost/freeze conditions. Sunshine
returns on Sunday with highs in the 50s with light winds.
- Mainly dry for the upcoming workweek except near coastal
areas. Otherwise, the other big story is a modest warming
trend with high pressure building in across the Northeastern
United States.
&&
.DISCUSSION...
KEY MESSAGE 1...Diminishing winds and clearing tonight with cold
low temps in the 20s and 30s with widespread frost/freeze conditions.
Sunshine returns on Sunday with highs in the 50s with light winds.
Model cross sections indicate that lingering mid level cloudiness
pushes south of the region tonight. This combined with high pressure
building in from the west coupled with diminishing winds and a dry
airmass in place will set the stage for a cold night. Low temps
should bottom out in the middle to upper 20s in many locations with
lower to middle 30s common in the urban heat islands as well as the
Cape/Nantucket where winds will not decouple. Widespread
frost/freeze conditions expected...But our Frost/Freeze program has
ended already so no headlines needed.
High pressure will result in sunny skies for Sunday. High temps will
be in the 50s...which is a bit below normal for this time of year.
However...with very little wind outside the Cape/Islands it will
feel significantly milder by afternoon than today.
High pressure remains in control of our weather Sunday night with
mainly clear skies. This will result in another good night of
radiational cooling with lows in the 20s and 30s.
KEY MESSAGE 2...Mainly dry for the upcoming workweek except near
coastal areas. Otherwise, the other big story is a modest warming
trend with high pressure building in across the Northeastern United
States.
General theme for the long term forecast is the return of drier and
somewhat warmer conditions going into the workweek as a broad ridge
of high pressure develops over the CONUS. Outside of this, guidance
continues to indicate the development of low pressure towards the
mid-Atlantic/Carolina coastal waters later Sunday into the day on
Monday. Ironically, this feature stems from last night's cold front
as it continues to move offshore and stall into a stationary
boundary. At the same time, lingering upper level energy cuts off
and induces the development of a frontal wave off the coast of the
Carolinas later Saturday night into Sunday morning. Still see a
signal for enough of a weakness in the ridge for low pressure to
move N and affect coastal areas Monday and Tuesday. Have continued
to see drier solutions with this storm as a dry airmass precedes the
northward precip shield. 12z global guidance 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 /00Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z Update
Tonight and Sunday...High confidence.
Brief period through 03z of wind gusts between 10 and 20 kts.
Otherwise...calm/light winds overnight into Sunday night except
N-NE winds persisting at 5-15 knots across the Cape/Islands.
Possibly occasionally VRBL conditions Sunday afternoon into the
evening mainly across interior terminals.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF.
Outlook /Monday through Thursday/...
Monday: VFR. Breezy.
Monday Night: VFR. Windy with local gusts up to 30 kt.
Tuesday: VFR. Windy with gusts up to 30 kt.
Tuesday Night: VFR. Windy with gusts up to 35 kt.
Wednesday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 35 kt.
Wednesday Night: Mainly VFR, with local MVFR possible. Windy
with areas of gusts up to 35 kt. Slight chance SHRA.
Thursday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 30 kt. Slight chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Sunday night...High confidence.
N wind gusts of 20 to 30 knots persist tonight...strongest of which
will be across our southern waters. Small craft headlines continue
for most of our waters. Some marginal lingering small craft advisory
conditions may persist across the southern waters Sun morning.
Otherwise...high pressure building in from the west will result in
winds/seas below small craft much of Sun into Sun evening.
However...distant ocean storm off the mid-Atlantic coast should
result in small craft advisory seas/wind gusts returning for our
southern waters toward daybreak Mon. Additional marine headlines
will be needed for much of the upcoming work week because of this
ocean storm.
Outlook /Monday through Thursday/...
Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 14 ft. Chance of rain showers.
Monday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 14 ft. Chance of rain showers.
Tuesday: Strong winds with gusts up to 40 kt. Rough seas up to
14 ft. Chance of rain showers.
Tuesday Night: Moderate risk for gale force winds with gusts up
to 45 kt. Rough seas up to 14 ft. Chance of rain showers.
Wednesday through Wednesday Night: Moderate risk for gale force
winds with local gusts up to 45 kt. Rough seas up to 15 ft.
Chance of rain showers.
Thursday: Strong winds with gusts up to 40 kt. Rough seas up to
14 ft. 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 Monday evening through Wednesday morning for
ANZ254>256-281>283.
&&
$$
DISCUSSION...Frank/FT
AVIATION...Frank/FT
MARINE...Frank/FT
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 17, 7:12 PM EDT----------------
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!
