409
FXUS61 KBOX 161712
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1212 PM EST Tue Dec 16 2025

.WHAT HAS CHANGED...
Confidence continues to increase for potential wind and minor
coastal flood impacts Thursday night into Friday.

&&

.KEY MESSAGES...
- Strong and possibly damaging winds possible late Thursday
  night into Friday with Gale force winds on MA/RI waters.

- Minor coastal flooding possible along south facing shores
  around high tide Friday morning.

&&

.DISCUSSION...
KEY MESSAGE 1...Strong and possibly damaging winds.

Main concern for this forecast is a "warmer" storm system that
is expected to track through the Great Lakes and swing a strong
cold front through southern New England Friday morning. Models
are in good agreement in showing a 500 mb trough becoming
negatively tilted as it rotates through New England, with decent
moisture transport and a fairly robust wind field aloft with
60-80kt low level jet at 925 and 850 mb, though we`re seeing a
trend that these stronger lower level winds will materialize as
system reaches Gulf of Maine, and as a result, NBMv4.3
probabilities for 50+ mph winds have come down a bit since
yesterday, although NBMv5.0 shows better potential especially
across RI and SE MA as well as coastal waters.

Taking a look at ensemble wind probabilities and a cursory look
at NAM/GFS forecast soundings gives higher confidence for
southerly gusts in 40-50 mph range late Thursday night into
Friday, but if we can warm into upper 50s Friday morning, we
would be able to more easily mix down 50-60 mph winds which
would increase the potential for wind damage. Additionally, we
will need to keep an eye on possibility of a fine line of
convection developing along cold front as it crosses SNE Friday
morning which could bring brief downpours and stronger wind
gusts but that is highly dependent upon having some instability,
something that can be seen on 00z RRFS which has 100-200 J/kg
of MUCAPE.

Behind front, cold advection takes hold with W/NW winds
potentially gusting to 40-50 mph, especially across higher
terrain and near coast (and on coastal waters) due to deepening
mixed layer and strong pressure rises. Another shot of cold
arrives Friday afternoon into Saturday, albeit not as cold as
what we just experienced.

KEY MESSAGE 2...Minor coastal flooding.

Confidence is lower than with wind impacts described above due
to timing of when highest surge will arrive and if it will
coincide with high tide along South Coast Friday morning,
roughly between 6 and 8 AM. This is tied to how quickly stronger
winds can ramp up and to some extent offshore seas as well.

If everything comes together, the worst case scenario would be
for minor coastal flooding along South Coast (less than 1 foot
deep on vulnerable shore roads) since we would need a surge
close to 3 ft. Stevens Institute ensemble guidance shows a
potential 1-2 ft surge while P-ETSS is under 1 ft and probably
underdone. Erosion should not be much of a factor given offshore
seas of 10-15 ft and only this high tide cycle being affected.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

18z TAF Update: High confidence.

VFR through the TAF period. Light SW winds today and tonight.
Winds at 2kft increase to 35-45 knots early wednesday morning
out of the SW. This will bring windshear concerns until late
morning when diurnal mixing kicks in. Winds Wednesday afternoon
will then gust up to 30-35 knots from the SW. Winds gradually
diminish wednesday night.

KBOS Terminal...High confidence in TAF.

VFR. Windshear possible tonight as winds aloft increase to 35-40
knots, but surface winds should be able to catch up with winds
aloft by mid morning.

KBDL Terminal...High confidence in TAF.

VFR. Windshear possible tonight as winds aloft increase to 35-40
knots, but surface winds should be able to catch up with winds
aloft by mid morning.

Outlook /Thursday through Saturday/...

Wednesday Night through Thursday: VFR. Breezy.

Thursday Night: MVFR/IFR conditions possible. Strong winds with
gusts up to 45 kt. Chance RA.

Friday: Mainly MVFR, with local IFR possible. Strong winds with
gusts up to 45 kt. Chance RA.

Friday Night: VFR. Windy with gusts up to 35 kt.

Saturday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today Through Wednesday Night...High confidence.

Calm winds and seas today with high pressure overhead.
Increasing SW winds tonight into tomorrow with gale force wind
gusts likey through Wednesday evening. Seas increase to 8-10
feet in the southern waters, and 6-8 feet in the eastern waters.

Outlook /Thursday through Saturday/...

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas.

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

Thursday Night: Moderate risk for gale force winds with gusts
up to 45 kt. Rough seas up to 14 ft. Chance of rain.

Friday: gale force winds with gusts up to 45 kt. Rough seas up
to 16 ft. Rain.

Friday Night: Strong winds with areas of gusts up to 45 kt.
Rough seas up to 13 ft. Slight chance of rain.

Saturday: Winds less than 25 kt. Seas up to 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 3 AM to 4 PM EST Wednesday for
     ANZ230.
     Small Craft Advisory from midnight tonight to 10 PM EST
     Wednesday for ANZ231-251.
     Small Craft Advisory from 1 AM to 10 PM EST Wednesday for
     ANZ232>235-237.
     Small Craft Advisory from 3 AM to 6 PM EST Wednesday for
     ANZ236.
     Small Craft Advisory from midnight tonight to 6 AM EST
     Thursday for ANZ250-254>256.

&&

$$

DISCUSSION...JWD
AVIATION...KP
MARINE...KP