-- Discussion containing changed information from previous version are highlighted. --
377
FXUS61 KBOX 260000
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
700 PM EST Sat Jan 25 2025

.SYNOPSIS...
Mainly dry Sunday with more seasonable temperatures through
Monday. Turning more windy Monday, with gusty winds peaking
Tuesday. A cold front will bring colder temperatures and
possibly snow squalls on Tuesday. Clipper system could bring
light snow to the region Wednesday. Arctic airmass will likely
bring very cold temperatures and wild chills near zero both
Thursday and Friday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
High pressure dominates through the rest of Saturday into the
overnight hours, but a trough of low pressure begins to approach
toward midnight/6am and one result will be the evolution of a 35-45
kt LLJ overhead, some of which mixes down as gusts 20-25 mph.
Overnight though this is mainly confined to the waters and immediate
coast, especially Cape Cod where there will be less inhibition by an
inversion. The moderating flow will also usher in a much milder
airmass than last night with lows only in the teens and 20s compared
to single digits.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
The mid level shortwave mentioned above sweeps across the region
early; just enough moisture and lift available to have some light
rain/snow chances over far southeast MA, though latest guidance has
trended further offshore with this feature, so those POPs may
continue to be reduced. Regardless, drier air quickly fills in in
the mid/upper levels leading to more sun through the day. Gusty
winds, though, will expand during the day, gusting 20 to 30 mph for
most. Fortunately temperatures will also be warmer Sunday thanks to
the moderating airmass, with highs in the upper 30s to low 40s.
Overnight the core of the jet moves offshore and winds will
diminish.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Key Points

* Mainly dry with increasing winds Monday.

* Snowsqualls possible Tuesday with very windy conditions.

* Clipper system may bring light snowfall Wednesday.

* Arctic airmass moves back in for Thursday and Friday with
  windchill values near zero again.

Monday:

Mainly dry Monday as the pressure gradient tightens ahead of a
strong low-pressure system and cold front dropping south from
Canada.  Winds become very gusty from the SW by up to 30mph on
Monday afternoon.  The strong southwesterly winds will allow temps
to warm into the mid to upper 30s, with low 40s possible near the
coasts.

Tuesday:

The cold front associated with the low moving out of Canada reaches
us Tuesday morning.  Still, some uncertainty on the exact timing of
the cold front as models have trended it slightly later.  The timing
will be important because snowsqualls become more likely with a
later frontal passage.  The environment will be primed for
snowsqualls as strong pressure couplet, Steep low-level lapse rates
above 7C/km, and good low to mid-level moisture.  With a slower
frontal passage, we can add more diurnal heating, boosting lapse
rates and low-level instability.  High temperatures will peak in the
30s again prior to the cold frontal passage, then quickly drop into
the 20s behind. Winds will also be near Wind Advisory threshold of
46mph on Tuesday prior to the frontal passage as a SW 850mb jet
around 60 knots moves over the region.  NBM probabilities for 46mph
gusts remain low, less than 20%, but the timing of the jet and front
could allow diurnal heating to mix down stronger winds with a slower-
moving system.

Wednesday:

A weak clipper system follows behind Tuesdays cold front.  Guidance
is still showing uncertainty in the track, with the GFS showing a
more southerly track over SNE, while the Euro and Canadian show a
more northern track over NNE.  With temperatures below freezing
behind the cold front, any precipitation that falls Wednesday will
fall as snow.  Any snow that does fall appears to be light at this
time, with limited moisture available, leading to QPF under a
quarter of an inch.  More details will come with this system as the
guidance continues to nail down the track.

Thursday and beyond:

High pressure looks to build back in for the remainder of the week,
but it will be accompanied by another Arctic airmass.  High temps
Thursday and Friday will be in the low to mid-20s, with overnight
lows once again in the single digits.  Winds remain blustery out of
the NW both days, keeping the wind chill values near or below zero.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
Forecast Confidence Levels:

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

Tonight through Sunday night...High Confidence.

VFR. Increasing SW wind Sunday with gusts to 20-30 kt
developing, diminishing overnight.

KBOS TAF...High Confidence in TAF.

VFR. Gusty SW winds increasing to 20-30 knots

KBDL TAF...High Confidence in TAF.

VFR. Gusty SW winds increasing to 20-30 knots.

Outlook /Monday through Thursday/...

Monday: VFR. Windy with local gusts up to 30 kt.

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

Tuesday: VFR. Windy with gusts up to 30 kt. Chance SHSN.

Tuesday Night: VFR. Breezy.

Wednesday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SN, slight chance RA.

Wednesday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SN.

Thursday: VFR. Breezy.
-- End Changed Discussion --

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight and Sunday...High confidence.

As modest low level jet develops, SW winds will increase tonight
with gusts 25-30 kt, then W gusts 25-30 kt Sunday. Seas build to 5-7
ft over the southern waters. SCA in effect tonight and Sunday.

Sunday night...High confidence.

W winds 15-20 kts with gusts 20-25 to start the night,
diminishing through the overnight hours. Seas 3-5 ft.

Outlook /Monday through Thursday/...

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of rough seas.

Monday Night through Tuesday: Strong winds with gusts up to
35 kt. Rough seas up to 11 ft. Gale warnings may be needed

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

Wednesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Local rough seas. Chance of snow, slight
chance of rain.

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Chance of snow, slight
chance of rain.

Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 8 ft. Slight chance of
snow.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 7 AM to 7 PM EST Sunday for ANZ230-
     236.
     Small Craft Advisory until 10 PM EST Sunday for ANZ231>235-237-
     251.
     Small Craft Advisory until 5 AM EST Monday for ANZ250-254>256.

&&

$$

SYNOPSIS...BW/KP
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...KP
AVIATION...BW/KP
MARINE...BW/KP