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000
FXUS61 KBOX 260835
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
335 AM EST Wed Jan 26 2022

.SYNOPSIS...
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High pressure brings an arctic airmass into the region today
and tonight. Not quite as cold Thursday afternoon along with
less wind, but nonetheless remaining colder than normal. Then
all eyes turn to a powerful coastal storm Friday night into
Saturday night, which will likely impact at least a portion of
the region with heavy snow, strong winds, coastal flooding and
dangerous seas. However, still some uncertainty on the exact
storm track and intensity, which will have a direct impact on
snow amounts and other storm details. Drier weather returns with
below normal temperatures Sunday.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

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330 AM update...

Today...

Arctic airmass slowly overspreads the region, on cold NNW drainage
flow with 925 mb temps lowering to about -14C to -16C by days end.
This strong low level cold air advection will preclude much if any
temp rise from temps early this morning. Given this and shallow
nature of the cold airmass, leaned toward the colder guidance
sources to derive high temps today. This only yields highs in the
low to mid 20s, upper teens for much of western-central MA. It will
feel even colder in response to NNW winds 10 to 20 mph, highest
winds over Cape Cod and the Islands.
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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...

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Tonight...

Arctic 1030+ mb high builds into the region, yielding a cold night
ahead with lows mainly ranging from -5 to +5 across much of the
region. NNW winds will trend more northerly and diminish. Thus, not
much of a wind chill overnight, nevertheless, very cold overnight.
Given diminishing winds, mostly clear conditions and a very dry
airmass, derived lows tonight from the colder MOS guidance. Before
winds diminish, NNW winds trending northerly, very cold air on this
trajectory over the relatively warm SSTs, will yield OES across the
outer Cape and possibly into coastal Plymouth county.  The NSSL WRF
and ARW are most aggressive with OES, and offer a coating up to an
inch possible in spots across the outer Cape and coastal Plymouth
county. This seems reasonable given 340 wind direction, delta-T of
24 degs from top of the mixed layer (-18C) to SSTs of +6C, and very
little directional shear in the boundary layer. Otherwise, dry
weather prevails.

Thursday...

A very cold start to the day, but slight improvement as ridge axis
aloft moves east of the region along with surface high sliding
offshore, offering weak return warm advection flow to setup. Temps
only a few degs higher than today, but light SSW winds and plenty of
sunshine will help offset the colder than normal temps.
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.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...



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.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
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Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

06z update...

Today...High confidence

VFR, dry weather and NW winds 10-20 kt, highest winds over Cape
Cod and the islands. Given this wind trajectory, ocean effect
snow showers likely remain just offshore of Cape Cod.

Tonight...High confidence.

VFR, dry weather with NNW winds at 5-15 kts. Gusts up to 20 kts
across the Cape/Islands. This more northerly wind trajectory
likely results in ocean effect snow showers and MVFR conditions coming
onshore to Cape Cod and possibly coastal Plymouth county. A
coating to an inch is possible.

Thursday...High confidence.

VFR, dry light and variable winds becoming SSW. Across the
outer Cape, MVFR cigs and vsbys possible in morning ocean effect
snow showers.

KBOS Terminal...High Confidence in TAF.

KBDL Terminal...High Confidence in TAF.

Outlook /Thursday Night through Sunday/...

Thursday Night: VFR. Breezy.

Friday: Mainly VFR, with areas MVFR possible. Slight chance SN.

Friday Night: Mainly VFR, with local IFR possible. Windy with
gusts up to 35 kt. Chance SN.

Saturday: Mainly VFR, with areas MVFR possible. Strong winds
with gusts up to 60 kt. SN likely.

Saturday Night: Mainly VFR, with local MVFR possible. Strong
winds with gusts up to 45 kt. Chance SN.

Sunday: VFR. Windy with areas of gusts up to 30 kt.
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&&

.MARINE...
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Forecaster Confidence Levels.

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

330 AM update...

Today...arctic high pressure approaches from the west, yielding NNW
10-20 kt winds across MA and RI waters, along with light freezing
spray.

Tonight...arctic high continues building east into New England. More
of a northerly wind 10-20 kt produces ocean effect snow showers over
the eastern MA waters, along with light freezing spray.

Thursday...high pressure moves offshore with light and variable
winds becoming SSW wind and light, generally 15 kt or less.

Outlook /Thursday Night through Sunday/...

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas locally approaching 5 ft.

Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain, slight chance of snow.

Friday Night: Low risk for gale force winds with gusts up to
40 kt. Local rough seas. Snow likely, rain.

Saturday: gale force winds with gusts up to 45 kt. Rough seas
up to 20 ft. Snow, rain.

Saturday Night: Strong winds with areas of gusts up to 45 kt.
Rough seas up to 20 ft. Snow likely, chance of freezing spray.

Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 15 ft. Chance of freezing spray,
slight chance of snow.
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&&

.BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 3 AM EST Thursday for ANZ250-254.
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&&

$$
SYNOPSIS...Nocera/BW
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...BW
AVIATION...Nocera/BW
MARINE...Nocera/BW