Marine Weather Net

Vineyard Sound Marine Forecast


THIS AFTERNOON

SE
WINDS
10 - 15
KNOTS

TONIGHT

S
WINDS
15 - 20
KNOTS

TUE

SW
WINDS
10 - 15
KNOTS

TUE NIGHT

SW
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ233 Forecast Issued: 1005 AM EDT Mon May 27 2024

SMALL CRAFT ADVISORY IN EFFECT FROM 9 PM EDT THIS EVENING THROUGH TUESDAY MORNING
This Afternoon...Se Winds 10 To 15 Kt. Gusts Up To 20 Kt. Seas 1 Foot Or Less, Then Around 2 Ft. Wave Detail: Se 1 Foot At 3 Seconds And S 1 Foot At 8 Seconds, Becoming Se 2 Ft At 3 Seconds And S 1 Foot At 8 Seconds. Areas Of Fog, Then Patchy Fog. A Chance Of Showers. Vsby 1 Nm Or Less.
Tonight...S Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Wave Detail: S 4 Ft At 8 Seconds And S 3 Ft At 4 Seconds. Patchy Fog. Showers. A Chance Of Tstms After Midnight. Vsby 1 Nm Or Less.
Tue...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 4 Ft. Wave Detail: S 4 Ft At 6 Seconds. Patchy Fog In The Morning. A Chance Of Showers In The Morning With Vsby 1 To 3 Nm.
Tue Night...Sw Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Evening. Seas 2 To 4 Ft. Wave Detail: S 3 Ft At 7 Seconds And Sw 1 Foot At 4 Seconds.
Wed...W Winds Around 10 Kt, Becoming Sw In The Afternoon. Seas 2 To 3 Ft. Wave Detail: S 3 Ft At 7 Seconds And W 1 Foot At 3 Seconds.
Wed Night...Sw Winds 5 To 10 Kt, Becoming Nw After Midnight. Seas 2 To 3 Ft. Wave Detail: S 3 Ft At 7 Seconds And Sw 1 Foot At 4 Seconds. A Chance Of Showers.
Thu...Nw Winds 5 To 10 Kt. Seas Around 2 Ft. A Chance Of Showers.
Thu Night Through Fri Night...W Winds 5 To 10 Kt. Seas Around 2 Ft. Winds And Seas Higher In And Near Tstms. 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
903am EDT Monday May 27 2024

Synopsis
Increasing chances for showers and thunderstorms ahead of an approaching cold front, mainly late this afternoon into this evening. This cold front moves offshore early Tuesday, with decreasing clouds and drier weather conditions. Generally dry from mid week into the weekend with more seasonable temperatures. Cannot rule out a few hit or miss showers later on Wednesday into Thursday.

Near Term - Through Tonight
9am

Fog has begun to dissipate across most interior zones and portions of the Cape but continues to hang tough along the immediate coastline as well as along Narragansetts Bay. With 1/4SM visibilities still observed at many coastal observation sites, did extend the dense fog advisory until noon today. Further extensions of the advisory are possible as some hi-res guidance, like the HRRR, show fog will hang tough though 21Z and will again redevelop closer to sunset this evening. Overall, not a particularly stunning Memorial Day for beachgoers.

Aside from the fog, we have seen some light showers tracking across central/wester MA and CT this morning. A more robust shield of rain is currently making it's way into western Connecticut, but with the LLJ oriented S to N, should mainly track north into the Litchfield Hills/Berkshires rather than push east. Still, Hartford and the CT River Valley may see a period of more widespread rainfall in the next two hours before we transition back to a more showery/drizzly mode ahead of approaching cold front this evening.

Previous

Regional radar data showed that the last few runs of the HRRR were too aggressive in triggering convection across our region early this morning. Based the forecast for next few hours off the 00Z HREF, as well as the latest RAP and NationalBlend runs. Thinking there is a risk for at last some showers as a decaying convective band approaches from eastern PA towards daybreak. Even lower risk for thunderstorms, but not impossible.

Issued a Dense Fog Advisory for RI and the south coast of MA.

Low pressure is expected to move across the Great Lakes into southern Canada today. The warm front associated with this low will struggle to move much north of our region. Noticeably cooler today, but still just as humid. Most of southern New England should see less than one quarter inch of rainfall today, where it rains at all. There is a risk for locally heavier rainfall from the stronger showers and less frequent thunderstorms.

Instability will be tough to generate today due to the stratus and fog which will take time and energy to dissipate. Overall MUCAPE values should remain less than 500-700 J/kg today, meaning there is not much of a severe weather threat, other than locally heavy rainfall.

Short Term - Tuesday
The cold front associated with a low pressure in southern Canada should move into our region some time tonight into Tuesday. Timing this front has been a challenge, as many different possibilities have been presented over the past few days. Consensus timing now has this front arriving after midnight tonight, but still somewhere just east of southern New England by Tuesday evening. We should not see the humidity diminish until this front passes completely by our region. Looking at another round of stratus and fog tonight.

The heaviest and most widespread rainfall is expected this evening into tonight. Not as much forcing for Tuesday, so thinking we can get through most of the day without rainfall.

Above normal temperatures continue.

Long Term - Tuesday Night Through Sunday
Highlights

* Dry for much of Wednesday with more seasonable temps. Could have spotty showers across the interior during the afternoon/evening.

* Shot for more widespread rain Wednesday Night into Thu, but there is a lot of uncertainty at this point.

* Overall looking pleasant Fri through the weekend with dry conditions. Temps near seasonable levels.

Tuesday Night through Wednesday... Stuck in blocky cyclonic flow through this period. Will have a trough over Upstate NY and a shortwave over the western Great Lakes to start. The first wave lifts northeastward, while the shortwave digs into the OH Valley. The shortwave begins interacting with the larger trough over the eastern Great Lakes/Mid Atlantic by late in the day. A cold front slides through Tuesday Night into early Wed. Could see a secondary cold front or surface trough sliding in late in the day.

Anticipating dry and quiet weather through the vast majority of this period. Does appear that there will be an opportunity for spotty showers Wednesday afternoon into the evening as the surface trough/secondary cold front is sliding in. Some uncertainty on this as winds will be W to WNW through the period. Should have a roughly 15-30 kt LLJ sliding through. This should aid in keeping us well mixed and drying things out as seen in the 1000-850 hPa RH. Moisture values really not that impressive with meh PWATs (Precipitable Waters) at +/- 1 STD above/below NAEFS/EPS model climo. The result are PWATs (Precipitable Waters) roughly of 0.75 to 0.85 inches. Dialed back our precipitation chances to slight for much of the period, though western areas could see some scattered activity push in toward the evening.

Only other adjustment made during this timeframe was to increase temperatures given the W/WNW flow. This should result in downsloping with 925 hPa temps of 9-15 degrees Celsius. Opted to bump us up to the 75th percentile of guidance. Highs will generally be in the 70s.

Wednesday Night through Thursday... Still in cyclonic flow. Will have that second shortwave/trough over the Mid Atlantic lifting toward/through southern New England by early Thu. It continues lifting toward Nova Scotia by late Thu, though could pivot across the Cape on Thu. A cold front will be lingering nearby. We could have an area of low pressure ride along the front, though there is a fair amount of uncertainty.

Big question mark during this period appears to be when the trough lifts toward us late Wednesday and how negatively tilted it becomes. Guidance is split with the GFS (Global Forecast System) lifting the trough into the Gulf of ME before it becomes negatively tilted, while the international guidance as a whole does it as it lifts into/just south of Long Island. This also results in the trough continuing to slowly lift through on Thu vs the more progressive GFS. The international guidance solutions put a baggy trough or perhaps cutoff nearby southern New England heading into Thu at 700 hPa, whereas the GFS does not. This cutoff solution would bring the risk for heavier precip.

Despite these details am not overly amped up at this point about the rain risk late Wednesday into Thu. NAEFS/EPS guidance show PWATs (Precipitable Waters) of 1 STD below model climo. Values anticipated to be generally around 0.75 to perhaps 1 inch. So, not a whole lot of moisture to work with. Though if we can get the trough nearby southern New England we could really squeeze out the moisture available. Should also have some roughly 1.5-2.5 km warm cloud layer depths. Despite not being amped up about it there is some ensemble hints at more widespread Quantitative Precipitation Forecast, especially across the south coast. The GEFS like the GFS is the least amped up with only low probs (10 percent) of 24 hr Quantitative Precipitation Forecast at or above 0.5 inches. The GEPS/EPS show low to moderate probs (10-50 percent) of 24 hr Quantitative Precipitation Forecast at or above 0.5 inches. Both the GEPS/EPS also showing some low probs of 24 hr Quantitative Precipitation Forecast at or above 1 inch. So will be something to keep an eye on. Though at this point not anticipating to have much instability. High temperatures on Thursday will be right around seasonable levels.

Friday through the weekend... Cyclonic flow continues through much of the period. A cutoff swings through much of New England on Fri as a ridge builds into the western/central Great Lakes. The ridge axis builds toward the eastern Great Lakes by late Sat and Sun. High pressure begins nudging in on Fri, but should build in for the weekend.

Generally am anticipating dry and quiet weather late in the week and through the weekend with high pressure in control. Do wonder if the cutoff will be close enough on Fri that we still can see some spotty showers, but for now think NBM slight chances suffice. Dry through the weekend with temperatures still around seasonable levels.

Marine
Forecaster Confidence Levels:

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

Through Tuesday...Moderate Confidence.

Dense marine fog expected as winds prevail from the east. Increased shower activity late today before a cold front brings the chance for more potent rain and embedded thunderstorms to the waters late this evening and early Tuesday morning. Winds increase, gusting between 25-30kt from the east before turning south behind this front. Waves climb in excess of 5 feet across the outer waters. Small Craft Advisories remain in effect for the eastern outer, and southern waters, including Nantucket Sound late today into tonight.

Outlook /Tuesday Night through Friday/... Tuesday: Winds less than 25 kt. Seas up to 5 ft. Patchy fog.

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

Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers.
Thursday: Winds less than 25 kt. Chance of rain showers.
Thursday Night through Friday: Winds less than 25 kt. Slight chance of rain showers.

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...Dense Fog Advisory until noon EDT today for MAZ020>024. RI...Dense Fog Advisory until noon EDT today for RIZ001>008.

Marine
Small Craft Advisory from 9pm this evening to 11am EDT Tuesday for ANZ232-233-235-237. Small Craft Advisory from 6pm this evening to 5am EDT Wednesday for ANZ250-254. Small Craft Advisory from 9pm this evening to 5am EDT Wednesday for ANZ255-256.