Marine Weather and Tide Forecast for Acushnet Center, MA

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

* Very cold wind chills early this morning between 0 and 10 above and briefly below zero in portions of the high terrain

* Highs today ranging from the upper 20s in the high terrain to the lower to middle 30s elsewhere.

Wind Advisory advisory has been cancelled as the strongest of the winds have come to an end...but it still will be windy today. Wind chills early this morning will be in the 0 to 10 above range and briefly below zero in the highest terrain.

Expecting winds to come up a bit this morning with diurnal mixing and a LLJ of 40-50 kts continuing over the region. Gusts of 25 to 35 mph still expected today with a few gusts up to 40 mph. Highs will range from the upper 20s in the high terrain to the lower to middle 30s elsewhere.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/
Tonight...

Expecting clear and calming conditions overnight as a surface ridge crests over New England. Clear skies and nearly calm winds will result in effective radiational cooling. Temperatures will likely fall into the teens across the interior and the low 20s for coastal locations where dew point temperatures will be a bit higher as a result of a light return flow.

Saturday...

Expecting mainly dry conditions for Saturday with an area of high pressure overhead. Expecting a somewhat warmer airmass with 850s warming considerably due to southwesterly winds aloft. Afternoon highs are between the middle and upper-30s, with the immediate south coast, Cape Cod, and islands reaching the low-40s. Could see some snow and coastal rain showers break out after 21z as a robust mid- level shortwave and trough approaches from the northwest later in the day.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
Key Messages...

* Saturday night into Sunday Snow Potential...
- 1-2" of snow possible south of I-90 - Narrow swath of 3-4" of snow possible near the south coast? - A dusting to 1" of snow north of I-90 - Track may still shift north or south...so adjustments possible

* Bulk of accumulating snow ends by Sun PM, but ocean effect snow showers linger into Sun night for Cape/ACK with 1-2" possible

* Arctic air follows Sun night-Mon...lows in the high single digits- teens & highs Mon in the 20s...Wind Chills -5 to 10 above Mon AM

* A weak disturbance may bring a very brief round of flurries/light snow showers Mon night with highs Tue in the upper 20s-middle 30s

* Pattern change with significantly milder temps Wed and especially by Thu when high temps may break 50

Details...

Saturday night and Sunday...

The main concern will be the northern extent of snow associated with a weak wave of low pressure passing to our south. This is a tricky forecast...as strong northern stream energy will result in colder/drier air working in from the northwest which will limit the northern extent of the snow shield and its duration. This will also result in this system being fairly progressive with the bulk of any accumulating snow occurring later Sat night into Sun morning. We think the majority of any accumulating snow will have ended by Sun afternoon...except for areas towards the Cape/Islands
In fact
we should see a good setup for ocean effect snow showers setup across the Cape and possibly Nantucket into Sunday night.

Based on the current guidance...thinking 1-2" of snow are possible for areas south of I-90. There might be a swath of 3-4" towards the south coast...if the stronger forcing can make it far enough north.
Meanwhile...areas north of I-90 probably only see a dusting to 1" of snow based on the latest model guidance. Now the track of this low pressure may still shift north or south...so these totals are certainly subject to change.

We also wanted to mention the lower probability outcomes. The low pressure system being suppressed even further south would result in little if any snowfall north of I-90 with just a coating to 1" south of I-90. A track further north would allow for 1-3" north of I-90 with 3-5" south of I-90
Again
these are lower probability outcomes...but still need to be considered.

So in a nutshell...the most likely outcome right now is a dusting to 1" of snow to the north of I-90 with 1-2" south of I-90 and perhaps a swath of 3-4" near the south coast. This will be the first accumulating snow event of the season for much of eastern MA/RI and even parts of CT
Fortunately
the bulk of the snow will fall late Sat night into Sun morning when travel is on the lighter side.
Nonetheless...untreated roads will likely be snow covered and slippery especially those traveling early Sunday morning.

Sunday night into Monday...

Initially cold low level northerly flow with fairly steep inversion layer will create a decent setup for ocean effect snow showers into Sunday evening across the Cape/ACK
In fact
SST differential from the top of the mixed layer may reach 25C to 30C! This should result in ocean effect snow showers across the Cape/Nantucket and we may see an inch or two of additional snowfall across parts of this region. Winds turn more NW later Sun night which should bring an end to most of the ocean effect snow showers.

Otherwise...one more shot of modified arctic air will work into the region Sunday night into Monday on gusty northwest winds. Low temps Sun night will fall back into the high single digits and teens.
Highs on Mon will only be in the 20s. Wind chills will likely be down to between -5 and 10 above Monday morning!

Monday night and Tuesday...

Still cold Mon night and Tue but with diminishing wind. Some of the guidance indicates a shortwave that may result in a few snow showers
Otherwise
Lows Monday night mainly in the teens with highs Tuesday in the upper 20s to the middle 30s.

Wednesday and Thursday...

Appears most of the long range guidance is an agreement in a pattern change. A developing -PNA allows more of a zonal flow of Pacific air to work across the U.S. Highs probably reach into the 40s across much of the region Wed with perhaps some areas reaching or breaking 50 by Thu. So this will be significantly milder weather than what we have been experiencing so far in December.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
Forecaster Confidence Levels...

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

18z TAF Update...

Today...High Confidence.

VFR. Westerly winds will continue to gust between 25 and 35 knots at times through the afternoon. A few spots may even see gusts briefly reach between 35 and 40 knots.

Tonight... High Confidence.

VFR. Gusty W winds diminish this evening and become southwest less than 10 knots late tonight.

Saturday... Moderate Confidence

Mostly VFR, possibly borderline MVFR for the Cape and Islands after 21z. Southwest winds between 5 and 10 knots with gusts up to 15 knots. Slight chance for areas of -SHRA/-SHSN across the Cape and Islands near 00z.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday Night through Tuesday/...

Saturday Night through Sunday: Mainly VFR, with local IFR possible. Breezy. Chance SN.

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

Monday Night: VFR. Breezy. Slight chance SHSN.

Tuesday: VFR. Breezy.

MARINE
Forecaster Confidence Levels...

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

Today Through Saturday..High confidence.

Morning gales for all of the waters. Gales become confined to the outer waters after 18z as CAA relaxes somewhat. Winds drop below gale threshold by 00z but seas between 5 and 7 feet into tonight will likely mean small craft advisories into the overnight. Improving conditions later tonight before a weak coastal low approaches later Saturday afternoon into the overnight.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Snow, slight chance of rain. Local visibility 1 to 3 nm.

Sunday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas locally approaching 5 ft. Snow. Areas of visibility 1 nm or less.

Sunday Night: Moderate risk for gale force winds with gusts up to 40 kt. Areas of rough seas. Chance of snow showers. Local visibility 1 to 3 nm.

Monday: Low risk for gale force winds with gusts up to 40 kt.
Areas of rough seas.

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

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

BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning until 1 PM EST this afternoon for ANZ230>237-251.
Gale Warning until 7 PM EST this evening for ANZ250-254>256.