Marine Weather Net

Coastal Waters out 25 NM South of Marthas Vineyard and Nantucket Marine Forecast


TODAY

SW
WINDS
5 - 10
KNOTS

TONIGHT

SW
WINDS
10 - 15
KNOTS

MON

SW
WINDS
15 - 20
KNOTS

MON NIGHT

SW
WINDS
15 - 20
KNOTS

The Marine Weather Forecast In Detail:
ANZ255 Forecast Issued: 716 AM EDT Sun Sep 22 2019

SMALL CRAFT ADVISORY IN EFFECT FROM LATE TONIGHT THROUGH MONDAY EVENING
Today...Sw Winds 5 To 10 Kt. Seas 2 To 3 Ft.
Tonight...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 4 To 5 Ft.
Mon...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 6 To 7 Ft.
Mon Night...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas Around 7 Ft. A Chance Of Showers In The Evening, Then Showers Likely After Midnight.
Tue...W Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 6 To 7 Ft. A Chance Of Showers.
Tue Night...Nw Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Evening. Seas 5 To 6 Ft.
Wed...W Winds Around 10 Kt. Seas 5 To 6 Ft.
Wed Night...W Winds 5 To 10 Kt. Seas Around 5 Ft.
Thu...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas Around 5 Ft.
Thu Night...W Winds 10 To 15 Kt, Becoming Nw After Midnight. Gusts Up To 20 Kt. Seas 4 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
702am EDT Sunday September 22 2019

Synopsis
High pressure remains in control into Monday with summer-like temperatures and dry weather. Showers likely Monday night along a sweeping cold front. High pressure settles in through midweek with mild days and cool nights.

Near Term - Until 6pm This Evening
7 am

Areas of dense fog remain a nuisance early this morning along S-coastal MA / RI / CT and within the CT / Pioneer River Valleys. Should see this burn off around 8 am as the sun rises, the boundary layer begins to mix out, and S/SW winds begin to increase. Will continue with the SPECIAL WEATHER STATEMENT out through 9 am to cover the poor visibility.

Otherwise expect plenty of sunshine once the morning low clouds and fog dissipate. Increasing SW wind, which should be enough to prevent the sea-breeze along the east coast of MA. Above normal temperatures continue, and should be similar to Saturday.

Swell continues to diminish along the coast today. Much lower risk for rip currents today. Caution is still advised if entering the water at unguarded locations.

Short Term - 6pm This Evening Through 6pm Monday
SW winds should help to maintain above normal temperatures through Monday. Humidity will be increasing, too. Looking at patchy fog once more tonight into early Monday morning.

A mid level cutoff moves over the Great Lakes by late in the day. This should produce an increase in clouds, and a risk for showers late in the afternoon across western MA. Decent instability parameters, so cannot dismiss the possibility of a few thunderstorms ahead of a cold front. Locally heavy rainfall will be possible in any thunderstorms.

Expecting increasing swell from the south Monday, this time from Tropical Storm Jerry. This should lead to another period with an elevated risk for dangerous rip currents, mainly along south- facing, ocean-exposed portions of the coast.

Long Term - Monday Night Through Saturday
*/ Highlights... - Showers likely Monday night - Warm-up and dry through midweek - Another sweeping cold front around Thursday night - Low confidence forecast into the following weekend

*/ Overview... Tropics are active. Multiple cast members supported by a phase 1 MJO crew. As members are drawn into the mid-latitude production they in part bring chaos to the show. From the NW Pacific to the NW Atlantic S equatorward, the multitude of systems, accumulated cyclone energy, latent heat release, all of which has the opportunity to be drawn N as the pattern slows and buckles, the subsequent result of warm air advection across Alaska and further downstream over Greenland that yields subsequent blocks. A CONUS trough.ridge, near climatological- record percentiles by the weekend, the NE-CONUS in the NE-periphery of the MS/OH Valley ridge with a +1-2 standard deviation temperature anomaly through the column, by weeks-end into the following weekend it'll be interesting as to the heat and humidity magnitude that'll be able to advect into the NE-CONUS beneath prevailing NW-flow aloft likely prior to SE-sweeping cold fronts. Rainfall opportunities that ensemble-means continue to show synoptically remain uncertain as to outcomes as well as how warm it potentially could get. Any nudge in the ensemble mean longwave pattern could put us either in a warm-dry pattern or a mild-wet setup. Nevertheless temperatures look to be above-average into early October as emphasized by CPC forecasts, but lower confidence with respect to precipitation outlooks. Dependence on the longwave pattern breakdown. Aside we really need some rain.

For now through the early half of the week, +WPO/+EPO signals with a robust N Pacific jet into the CONUS, energy cascades E. Grasping at continental-moist airmasses, there's opportunity for some rainfall Monday night and again Thursday night (however the latter becoming weighed down by increasing heigheights as the pattern begins to buckle). Mild days and cool nights. Break down details below.

*/ Discussion... Monday night... Showers likely. Cold frontal lift, convergent low-level winds, all beneath a neutral-tilt trough with attendant vortmax, cyclonic flow, and jet dynamics, certainly forcing will act upon a continental- moist airmass with precipitable waters close to 2-inches. Narrow ribbon of moist-adiabatic, conditionally-unstable profile with some decent W shear, can't rule out some heavy downpours, maybe a rumble of thunder. Forecast guidance has been all over the place with rain- fall. But given synoptics would think something will squeeze out. Deep-layer moisture with the aforementioned ribbon well up to H5-3 and warm-cloud bases up to 14 kft, some areas could see that 0.50 if not more. Just a challenge to where exactly but there's indication of deep-layer lift will occur somewhere. Likely PoPs. Mild.

Tuesday into Wednesday... Clouds lingering. Light showers N beneath the closed mid-upper level low slowly working E. Downsloping W/NW flow. Gradual clearing, mild days, cool nights. Above-average temperatures when normally for late September we should see highs around 70, lows around 50. Expect it to be around +5 degrees with respect to the two.

Thursday into Thursday night... Sweeping cold front and a chance of showers. However heigheights on the rise as the longwave pattern buckles, a trough digs over the W CONUS with the ridge building E. Rainfall outcomes could be suppressed prior to ending up on our doorstep. Remaining mild.

Friday onward... Low confidence forecast depending on the longwave CONUS setup. We could end up warm and dry, or rather mild with on and off rainfall chances along sweeping cold fronts.

Marine
Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

Short Term /through Monday/...High confidence.

Light winds this morning, becoming S-SW winds and increasing to 15-20 kt this afternoon and evening with gusts up to 25 kt possible toward sunrise Monday. Patchy fog and low clouds may limit vsby this afternoon through through tonight. Dry weather prevails. Seas build across the outer coastal waters. Small Craft Advisories posted for late tonight into Monday.

Outlook /Monday Night through Thursday/...Moderate confidence.
Monday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain showers, slight chance of thunderstorms.

Tuesday: Winds less than 25 kt. Local rough seas. Slight chance of rain showers.
Tuesday Night: Winds less than 25 kt. Local rough seas.

Wednesday through Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.
Thursday: Winds less than 25 kt. Seas up to 5 ft.

NOAA Boston MA Office: Watches - Warnings - Advisories


CT...None. MA...None. RI...None.
MARINE...
Small Craft Advisory from 1am to 8pm EDT Monday for ANZ232>235-250-254>256. Small Craft Advisory from 6am to 8pm EDT Monday for ANZ231- 237.