Marine Weather Net

Montauk NY to Marthas Vineyard out 20 NM South of Block Island Marine Forecast


25 - 30


25 - 30


25 - 30


25 - 30

The Marine Weather Forecast In Detail:
ANZ256 Forecast Issued: 116 PM EST Sat Jan 23 2021

This Afternoon...Nw Winds 25 To 30 Kt With Gusts Up To 35 Kt. Seas 5 To 8 Ft.
Tonight...Nw Winds 25 To 30 Kt With Gusts Up To 40 Kt. Seas 6 To 8 Ft.
Sun...Nw Winds 25 To 30 Kt With Gusts Up To 40 Kt. Seas 6 To 8 Ft.
Sun Night...Nw Winds 25 To 30 Kt With Gusts Up To 35 Kt, Diminishing To 15 To 20 Kt With Gusts Up To 25 Kt After Midnight. Seas 5 To 8 Ft.
Mon...Nw Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Morning. Seas 2 To 4 Ft.
Mon Night...N Winds Around 10 Kt, Becoming Ne With Gusts Up To 20 Kt After Midnight. Seas 2 To 3 Ft.
Tue...Ne Winds 15 To 20 Kt. Seas 2 To 4 Ft. A Chance Of Rain And Snow. Vsby 1 To 3 Nm.
Tue Night Through Wed Night...N Winds 15 To 20 Kt. Seas 3 To 5 Ft. Seas Are Reported As Significant Wave Height, Which Is The Average Of The Highest Third Of The Waves. Individual Wave Heights May Be More Than Twice The Significant Wave Height.
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Area Forecast Discussion
National Weather Service Boston/Norton MA
1230pm EST Sat Jan 23 2021

A cold and blustery weekend with possible sub-zero wind chills by Sunday morning. Winds slacken on Sunday night as high pressure builds into Southern New England through Monday night. A system passing to our south may bring a minor accumulation of snow south of the Massachusetts Turnpike on Tuesday. High pressure then becomes re-established for most of the workweek, with temperatures around seasonable levels. A coastal low near the mid-Atlantic waters on Thursday may brush our far southern areas or pass far enough south to be a miss.

Near Term - Until 6pm This Evening
1 PM

Arctic front continues to drop through southern New England after bringing a dusting to half inch of snow from Worcester east to the outer Cape. Showers have largely moved offshore and things should be dry the rest of the day. Winds are gusting 25 to 30 mph and will remain elevated.


Radar showing some southeastward-moving snow showers into the Route 2 corridor and the Merrimack Valley. These will continue to pass southeast toward the North Shore/Metro Boston and offshore. As they do so however, they will briefly reduce visibility and perhaps produce a coating of new snow. Expect by mid- morning that these passing snow showers will have moved into the coastal waters.

Otherwise, considerable cloudiness and northerly winds have kept current temperatures running milder than forecast expectations. We're also still awaiting the arrival of the colder/drier air which still is back across central NY. Expect onset of cold advection around mid morning, with increasing northwest wind gusts. Didn't make any changes to temps, which appear on track.

4am update:

The core of a high pressure remains to our west today. While this high should be close enough to keep our weather mainly dry, it will not be quite close enough to force winds to diminish. In fact, expecting the opposite effect where the modest cold air advection will increase the gradient wind across southern New England, especially this afternoon.

Temperatures will be below normal today, with most areas not getting out of the 20s.

Cannot rule out a few snow showers or flurries this morning, especially towards the east coast.

Short Term - 6pm This Evening Through 6pm Sunday
Not much change in conditions tonight into Sunday. Still gusty winds and turning sharply colder compared to what we have been most of this month. Minimum wind chill temperatures tonight below zero across most of southern New England. Not low enough where am thinking we would need a Wind Chill Advisory. Thinking we could see some isolated gusts up to Wind Advisory strength across the outer Cape tonight. Will let the next shift reevaluate.

Long Term - Sunday Night Through Friday
Highlights... * Dry weather prevails through Monday night under high pressure.

* Light-accumulating snow mainly across western MA, CT into southern RI Tues as system passes to our south.

* High pressure returns for mid to late week with mainly dry weather; do have to monitor coastal storminess near the mid- Atlantic region Thurs that may brush our southern areas but not a sure bet.


Sunday Night into Monday:

High pressure over the Appalachians continues to build east into our area Sunday night, and remains established across Southern New England through Monday night.

For Sunday night, we should see slackening NW wind speeds early, taking longer to occur across eastern coastal MA. Good radiational cooling seems likely, especially our interior areas where winds will ease sooner than areas further east. MOS ordinarily would do fairly well in such a pattern for temperatures, but may be too cold given its assumptions that there is a snowpack; so for lows I utilized an NBM/MOS blend to not go quite as low as MOS would reflect. Brings lows mainly into the low-mid teens, with single digits across parts of the Pioneer Valley and into the Berkshires.

High pressure continues to govern on Mon, with full sun turning filtered late in the day. By evening, most areas should trend OVC in terms of sky cover. Under modest northerly winds which should turn more NNE/NE by Monday night, showed upper 20s to upper 30s highs with lows mid teens to lower 20s.

Tuesday into Tuesday Night:

Primary low pressure at 12z Tues over IL/IN, associated with a 500 mb shortwave trough which rounds the northwest periphery of a ridge axis over the coastal southeast CONUS. Shortwave aloft more or less shears out as it nears the mid-Atlantic/lower Hudson Valley region on Tues, with secondary coastal development taking shape later Tues into Tues night.

00z guidance suite seems to be coming into better agreement on what is appearing to be a light-accumulating snow for Tues into Tues evening. Of the deterministic guidance, the GFS is the furthest north and also packs a little more Quantitative Precipitation Forecast than the ECMWF (European Centre for Medium-Range Weather Forecasts) and the Canadian GEM. Shearing vort energy, limited Quantitative Precipitation Forecast, a progressive system and high pressure to our northeast supplying dry air are also limiting factors for more appreciable accumulating snows. Opted for Chance-level Probability of Precipitation across CT into western MA where the best chance for limited/minor accumulation may be on Tues with up to a couple inches of snow here, tapering to slight chance further to the north and east. NBM-based snow probs also support a light/minor accumulation of snow mainly into CT, western MA and central/southern RI. Drier air eventually wins out and shifts precipitation axis into our far southern waters Tues night.

Highs mid 20s to the lower-mid 30s on Tues, with lows mid teens to mid 20s.

Wednesday into Wednesday Night:

High pressure to re-build back into SNE for midweek. Despite dry weather, still some RH left behind supporting partly to mostly cloudy conditions and onshore NE flow. Highs upper 20s to the mid upper 30s with lows upper teens to mid 20s.

Thursday into Friday:

Models showing a deepening cyclone near the coastal mid-Atlantic and Carolinas on Thurs, moving eastward mainly south of 40N latitude. It remains to be seen if SNE will see any (fringe) impacts from this forecast cyclone, as there's significant latitudinal spread in low centers. In terms of the operational models, the ECMWF is furthest south and would offer a continuation of dry northerly flow. The GEM and more so the GFS (furthest north/somewhat closer to SNE) would bring precipitation to our southern roughly third of the forecast area. Will need to keep tabs on this system and its developments, but at the moment ensembles presently support a miss or at worst a glancing blow to our southern areas.

System pulls away Thurs night with high pressure building back in for Friday supporting dry weather.

Temperatures project around seasonable levels for late-week.

Gusty west to northwest winds continue across the waters and linger through Sunday. Gale Warnings remain in effect through Sunday evening. The air will be cold enough where there is a concern for freezing spray across most of the coastal waters into Sunday. Decided to issue Freezing Spray Advisories for portions of the eastern coastal waters tonight due to the possibility of moderate freezing spray. Threat of freezing spray diminishes some during the day Sunday.

Outlook /Sunday Night through Wednesday/... Sunday Night: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Freezing spray.

Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Local visibility 1 to 3 nm.

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain, slight chance of snow. Visibility 1 to 3 nm.

Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Local visibility 1 to 3 nm.

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

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...None. RI...None. MARINE...Freezing Spray Advisory from 9pm this evening to 7am EST Sunday for ANZ231>234. Gale Warning until 6pm EST Sunday for ANZ230>237-250-251- 254>256. Freezing Spray Advisory from 9pm this evening to 10am EST Sunday for ANZ251.