Marine Weather Net

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




5 - 10




5 - 10

The Marine Weather Forecast In Detail:
ANZ256 Forecast Issued: 716 AM EDT Thu Oct 22 2020

Today...W Winds Around 5 Kt, Becoming Ne This Afternoon. Seas 3 To 5 Ft. Areas Of Dense Fog This Morning, Then Areas Of Fog This Afternoon. Vsby 1 Nm Or Less.
Tonight...E Winds 5 To 10 Kt. Gusts Up To 20 Kt After Midnight. Seas 4 To 6 Ft. Areas Of Fog. Vsby 1 Nm Or Less.
Fri...E Winds Around 10 Kt. Gusts Up To 20 Kt In The Morning. Seas 5 To 7 Ft.
Fri Night...E Winds 5 To 10 Kt, Becoming S After Midnight. Seas 6 To 7 Ft.
Sat...W Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 25 Kt In The Afternoon. Seas 6 To 7 Ft.
Sat Night...Nw Winds 10 To 15 Kt, Becoming N After Midnight. Gusts Up To 25 Kt. Seas 5 To 7 Ft.
Sun Through Mon...Se Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 4 To 6 Ft.
Mon Night...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 4 To 5 Ft. A Chance Of Showers. 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.
SHARE THIS PAGE:           
Area Forecast Discussion
National Weather Service Boston/Norton MA
704am EDT Thu Oct 22 2020

A weak cold front will pass across northern Massachusetts early this morning. This front gives way to high pressure which lasts through the rest of the workweek, with generally dry weather and continued unseasonably mild temperatures. A cold front will cross the region later Saturday followed by much cooler weather for Sunday. An unsettled weather pattern develops early next week as a series of fronts move across the region. This will bring the chance of showers at times Monday into Wednesday with perhaps the greatest risk for a period of steady rain late Tuesday night into Wednesday.

Near Term - Until 6pm This Evening
* Unseasonably mild this afternoon and a bit humid too at least away from the very immediate eastern MA coast

7 AM

Patchy dense fog continued to impact the region very early this morning, but not nearly as widespread compared to yesterday at this time. The exception was near the south coast where fog was more widespread and the Dense Fog Advisory remains in effect until 9 AM.

Expect most of the patchy fog to burn off by mid morning, but will last a bit longer in some locations near the immediate south coast, Cape and Islands. Otherwise, we are off to a very mild start with many locations in the upper 50s to the lower 60s. Previous forecast remains on track.

Otherwise, a mild southwest flow aloft is maintained across Southern New England early this morning, north of a strong Bermuda ridge centered over the mid-Atlantic coastal waters. At the surface, a cold front was moving through northern MA and up into NH. As reflected in the enhancement shown in nighttime microphysics RGB imagery, low clouds and intervals of fog were common south of the Mass Pike in the warm sector. The cold front will continue to progress eastward early this morning, and west to northwest winds to allow for the low clouds and fog to shift southeast and scatter out as the day progresses. This should support mostly sunny conditions soonest across most of the interior, and more delayed into the late- AM/early-PM towards the South Coast and Cape Cod. We are still looking at a quite mild day today given more sunshine and 925 mb temps around +13 to +15 Celsius. This should bring high temperatures today to values well into the 70s for most. However by early to mid- afternoon, high pressure building into the Gulf of Maine will bring an onshore NE/E flow to coastal/eastern MA. As this occurs, it will bring falling temperatures thru the remainder of the afternoon given the cooler SSTs (around the upper 50s). Late in the day, E/SE flow will also help draw some of the lower clouds south of the Islands back towards the South Coast and Cape Cod, but this should really begin to happen no sooner than late in the day per the 00z HREF.

Short Term - 6pm This Evening Through 6pm Friday

Passage of a warm front across northern New England and a ridge extending through the Gulf of Maine will allow for a modest southeast return flow regime to set up across Southern New England. This return flow will allow for increasing low clouds to advance westward/northwestward through the evening. Lowest clouds actually may tend toward the CT Valley and particularly the east slopes of the Berkshires as this moist flow becomes banked against the lee of the mountains. NAM and GFS-based BUFKIT soundings at BAF and BDL show a high-RH layer that's about 4000 ft thick from the surface, and that increases confidence in low clouds in this area. There may be intervals of mist, drizzle or very light rain at times in this area, but any Quantitative Precipitation Forecast is nil. Rest of Southern New England should be dry. Lows should trend mildest further west with more clouds (in the mid/upper 50s). Slightly less cloud coverage across central/eastern MA and RI could allow for enough cooling to bring lows in the lower 50s. These are still above normal for late-October climo lows (low-mid 40s).


Surface ridging extending into coastal New England will continue to shift slightly westward, which will maintain a continued modest SE flow regime. Considerable cloudiness early in the day should trend more variably cloudy with less clouds east. However even across western MA, northwest CT into the Berkshires, decreasing/scattering of cloudiness is anticipated but it may take until afternoon before skies start to trend partly cloudy there. With the milder start but more cloudiness to be overcome in the west, and less clouds but more expected sunshine in the coastal plain into southeast New England, highs may end up being fairly similar regionally in the upper 60s.

Long Term - Friday Night Through Wednesday
Highlights... * Mainly dry & unseasonably mild Sat

* Dry and turning much cooler Sat night & Sun

* Unsettled weather possible at times Monday through Wednesday with the greatest potential for a period of steady rain late Tuesday night/Wed

Details... Friday night... Weak ridge of high pressure brings quiet/dry weather Fri night other than the risk for some low clouds and fog patches. It will be rather mild for this time of year too with overnight lows only dropping into the middle 40s to the lower 50s.

Saturday... Southwest flow ahead of an approaching cold front will result in one more unseasonably mild afternoon. Some low clouds in the morning should give way to partial sunshine by afternoon. 850T around +10C along with a relatively mild start should push Sat afternoon highs near 70 in many locations. Low risk for a brief sprinkle/spot shower can not be ruled out Sat afternoon with the cold front, but deep moisture/forcing is quite limited so most locations likely remain dry.

Saturday night and Sunday... A 1030 MB high pressure system across eastern Canada will result in dry but much cooler weather working into the region Sat night/Sunday behind the cold front. Low temps by daybreak Sunday will range from the middle 30s to the lower 40s in most locations. Despite plenty of sunshine on Sun, cool low level northeast flow will hold high temps mainly in the lower to middle 50s. Those readings will be about 15 to 20 degrees cooler than Saturday, so certainly a taste of fall to close out the weekend.

Monday through Wednesday... Forecast uncertainty increases in the Monday through Wednesday time frame. A wave of low pressure will pass to our northwest on Monday allowing for a warm front to cross the region. Highs may recover back into the 60s along with the threat for a period of showers. Greater risk for steadier rain may be north of our region Mon, closer to the better dynamics.

Latest 00z guidance indicates that a cold front will cross the region late Monday night into Tuesday am with perhaps a few more showers and cooler temps. Appears the greatest risk for a period of steady rain might be late Tuesday night into Wed, where some ensembles indicate a wave of low pressure cutting near or south of our region bringing us a cool rain. That being said, lots of spread exists in the possible outcomes late Tuesday night and Wednesday so that rain is not a certainty at this point. We will have to see how models trend over the next few days, but it is something to watch.

The main concern for mariners is the building long-period (14-15 second) swell associated with distant Hurricane Epsilon. We are looking at a fairly long-duration period of seas over 5 ft, conditions which are likely to continue into the upcoming weekend. Already seeing increasing seas on most of the ocean waters per buoys, and these seas are expected to continue to build today into Friday, peaking on Saturday. To best capture the period of higher seas, the existing SCA (Small Craft Advisory) has been extended into Saturday evening. Seas on the offshore waters will build to 4-6 ft today, then 5-7 ft tonight into Friday and around 6-9 ft on Saturday. High surf will also develop through this period for southern and eastern-exposed beaches, but particularly Friday into Saturday.

Winds will remain below SCA (Small Craft Advisory) levels through Saturday, and while a brief period of NW winds are expected today, winds should be predominantly east to southeast later this afternoon into Friday night.

Fog from the overnight will dissipate early today on the eastern waters, though it may take until the afternoon before fog disperses on the southern waters.

Outlook /Friday Night through Monday/... Friday Night: Winds less than 25 kt. Rough seas up to 8 ft.

Saturday: Winds less than 25 kt. Rough seas up to 9 ft.

Saturday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 9 ft.

Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas.
Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft.

Monday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain showers.
NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...Dense Fog Advisory until 9am EDT this morning for MAZ020>024. RI...Dense Fog Advisory until 9am EDT this morning for RIZ006>008.
Small Craft Advisory from 10am this morning to 8pm EDT Saturday for ANZ250-254>256.