Marine Weather Net

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


10 - 15


10 - 15


5 - 10


5 - 10

The Marine Weather Forecast In Detail:
ANZ256 Forecast Issued: 419 PM EDT Sun Apr 21 2024

Tonight...W Winds 10 To 15 Kt, Becoming Nw After Midnight. Gusts Up To 20 Kt. Seas 2 To 3 Ft. Wave Detail: Sw 2 Ft At 4 Seconds And Se 2 Ft At 7 Seconds.
Mon...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming W 5 To 10 Kt In The Afternoon. Seas 2 To 3 Ft. Wave Detail: Nw 2 Ft At 4 Seconds And Se 1 Ft At 7 Seconds.
Mon Night...S Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 9 Seconds And Sw 1 Ft At 4 Seconds.
Tue...S Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: S 2 Ft At 8 Seconds And Se 2 Ft At 9 Seconds.
Tue Night...S Winds 10 To 15 Kt. Gusts Up To 20 Kt After Midnight. Seas 2 To 3 Ft. Wave Detail: S 3 Ft At 5 Seconds And Se 1 Ft At 10 Seconds.
Wed...Sw Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 3 To 5 Ft. Wave Detail: Sw 5 Ft At 6 Seconds And Se 2 Ft At 9 Seconds. A Chance Of Showers.
Wed Night...Nw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 4 To 6 Ft. A Chance Of Showers In The Evening.
Thu...Nw Winds Around 15 Kt With Gusts Up To 25 Kt. Seas 3 To 5 Ft.
Thu Night And Fri...W Winds 10 To 15 Kt. Gusts Up To 20 Kt. Seas 2 To 4 Ft.
Fri Night...Sw Winds 10 To 15 Kt. Seas Around 2 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
934pm EDT Sunday April 21 2024

A ridge of high pressure will result in dry weather through Tuesday with mild days and chilly frost nights, along with elevated fire weather potential. Unsettled, wet and cool on Wednesday. Drier late in the week and heading into the weekend.

Near Term - Until 6am Monday Morning
935 PM

* Areas of frost tonight with lows mainly in the 30s

Previous forecast is on track. Low pressure well to our south and approaching weak trough/cold front has resulted in a fair amount of mid level cloudiness into this evening. As this weak dry front crosses the region it will take the mid level cloudiness with it. Therefore...expect clearing skies from northwest to southeast overnight. Still some uncertainty if winds will completely decouple...but probably will for a few hours in the typical low-lying locations. This will allow overnight low temps to bottom out mainly in the 30s with some upper 20s possible in the normally coolest spots of western MA. Areas of frost are also Frost Advisories continue across CT/RI/SE MA where we have passed the median day of the last freeze.

Short Term - 6am Monday Morning Through Monday Night
This dry front lingers during the morning, before moving back north as a warm front late in the day. High pressure moves just offshore Monday night. Dry weather continues through this portion of the forecast. Slightly below normal temperatures expected.

Long Term - Tuesday Through Sunday

* Seasonable temperatures in the extended forecast

* Modest rain event on Wednesday with strong wind gusts Wednesday night into Thursday

* High pressure and dry weather take over late week into next weekend

Tuesday and Wednesday

High pressure remains in control on Tuesday but will shifting east over the coastal waters. This will allow return flow from the south to advect slightly higher temps over the region that what should be observed on Monday. Nonetheless, temps will be close to normal, maybe a few ticks above normal across southern New England with highs in the upper 50s to low 60s common. Coastal areas may remain a bit cooler, especially if a sea- breeze circulation is able to develop (upper 40s to lower 50s).

Moisture continues to increase in response to southerly flow ahead of northern stream short-wave energy approaching from the Midwest. This system will bring our next chance for substantial rain, but there are no signals that this will be an impressive rain event by any means. Forcing for ascent associated with the system is rather modest and will be mainly driven by positive vorticity advection east of the short-wave trough axis. The trickier part of the forecast at this time range is just how much moisture will be available. Ensemble guidance reveals a rather large spread in PWATs (Precipitable Waters) ranging from 0.25 to 0.75 inches in the column. This of course will play a role in just how much precipitation will be observed. The consensus is for anywhere from 0.1 to 0.25 inches with the higher amounts focused to the north and west. However, should moisture over achieve, 0.25 to 0.5 inches could be in the cards as well. Regardless, confidence is moderate to high that Wednesday will feature wet/rainy conditions across much of the region. Temperatures will continue to hover in the near-normal range, but slightly below normal given the precipitation and extensive cloud cover (low to mid 50s).

Wednesday night and Thursday

As the surface cold front associated with the aforementioned rainmaker on Wednesday pushes through the region Wednesday night into Thursday, a Cold Air Advection regime will support a period of gusty northwest winds over southern New England. There is uncertainty in how strong the low level jet will be, but ensemble probabilities of wind gusts exceeding 30 mph are greater than 50 percent across much of the region Wednesday night into Thursday. In addition to the wind, Wednesday night will feature chilly temperatures as a -5C 925 hPa air mass settles over the region by Thursday morning. Expect lows THursday morning to bottom out below freezing across much of southern New England. After a chilly start, efficient mixing in the Cold Air Advection regime will allow temps to rebound to the mid to upper 50s. The column will behind the cold front will be very dry with PWATs (Precipitable Waters) less than 0.2 inches. This should support dry weather and abundant sunshine on Thursday.

Friday through Sunday

High pressure builds over the region by the end of the week. This will bring and end to the gusty post frontal winds that are expected Wednesday night/Thursday. Expect the high pressure pattern to support dry/seasonable conditions Friday and Saturday with highs/lows in the upper 50s/lower 60s and mid 30s - low 40s respectively. As high pressure shifts east toward the end of the weekend, increasing moisture may lead to some unsettled weather on Sunday, but confidence on what can be expected is low at 7 days out.

Forecaster Confidence Levels:

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

Through Monday Night...High Confidence.

A relatively weak pressure gradient will keep winds and seas below Small Craft Advisory thresholds through Monday night. Light northwest winds Monday could lead to late seabreezes along the coasts. Light south winds developing Monday night.

Outlook /Tuesday through Friday/... Tuesday through Tuesday Night: Winds less than 25 kt.

Wednesday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers.
Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Slight chance of rain showers.
Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas.

Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday: Winds less than 25 kt.

Fire Weather
Today and Monday... There will be elevated fire weather concerns Monday. Given that we are in a pre-greenup, dry westerly flow will allow for minimum afternoon relative humidity values to drop to between 20 and 30 percent across the interior. Expecting wind speeds to be lower Monday, but there could be W to NW gusts up to 20 mph.

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...Frost Advisory until 7am EDT Monday for CTZ002>004. MA...Frost Advisory until 7am EDT Monday for MAZ013-016>023. RI...Frost Advisory until 7am EDT Monday for RIZ001>008.