Nantucket Sound Marine Forecast
| This Afternoon...N Winds 10 To 15 Kt, Becoming Ne 15 To 20 Kt. Seas 2 To 3 Ft. Wave Detail: Ne 3 Ft At 5 Seconds And Nw 2 Ft At 4 Seconds. |
| Tonight...E Winds Around 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. Wave Detail: Se 3 Ft At 5 Seconds. Patchy Fog After Midnight With Vsby 1 To 3 Nm. |
| Sun...S Winds 20 To 25 Kt With Gusts Up To 35 Kt. Seas 4 To 6 Ft. Wave Detail: Sw 5 Ft At 5 Seconds And E 3 Ft At 7 Seconds. Patchy Fog. Showers Likely In The Afternoon. Vsby 1 Nm Or Less. |
| Sun Night...Sw Winds 20 To 25 Kt With Gusts Up To 30 Kt, Becoming Nw 10 To 15 Kt After Midnight. Seas 4 To 6 Ft, Subsiding To 2 To 4 Ft After Midnight. Wave Detail: Sw 4 Ft At 5 Seconds And S 3 Ft At 8 Seconds, Becoming W 2 Ft At 4 Seconds And S 2 Ft At 8 Seconds. Showers, Mainly In The Evening. Patchy Fog In The Evening With Vsby 1 To 3 Nm. |
| Mon And Mon Night...W Winds 15 To 20 Kt. Seas 2 To 3 Ft. Wave Detail: W 3 Ft At 4 Seconds And S 2 Ft At 8 Seconds. |
| Tue And Tue Night...W Winds 10 To 15 Kt, Becoming Nw 15 To 20 Kt. Seas 2 To 3 Ft. Wave Detail: Sw 2 Ft At 3 Seconds And Se 1 Foot At 8 Seconds. A Chance Of Showers. |
| Wed And Wed Night...Ne Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming S 5 To 10 Kt. Seas 2 To 3 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. |
| Area Forecast Discussion National Weather Service Boston/Norton MA 1132am EDT Sat April 4 2026 .WHAT HAS CHANGED... No significant changes; forecast remains on track. .KEY MESSAGES... - After mild weather Friday, another backdoor front brings a return to chilly weather Saturday afternoon, especially eastern MA. - Showers Sat night and Sunday, milder with highs in the upper 50s and lower 60s. - Could see a few rain/snow showers Monday night/ Tuesday morning,but otherwise expecting cooler temperatures and dry weather for a good portion of next week. - Second half of next week looks mainly dry with temperatures on the rise. KEY MESSAGE 1...After mild weather Friday, another backdoor front brings a return to chilly weather Saturday afternoon. Mild during the predawn hours of Saturday across SNE, with prefrontal airmass and dew pts in the upper 40s and lower 50s across the region. This moist airmass (by early April standards), courtesy of a modest low level prefrontal southwest jet, is the culprit for the low clouds, fog and spotty drizzle along the south coast. As a cold front approaches from the NW, surface winds over SNE will veer to the WNW toward daybreak, shunting this low level moisture offshore and giving way to clearing/improving conditions along the south coast toward sunrise. As northern stream jet energy streams across the maritimes this morning, its corresponding surface boundary will traverse across SNE in the form of a backdoor front, from east to west. Hence, warmest part of the day will be this morning, along with sunshine thru high clouds, warming temps through the 50s and 60s. Then followed by a noticeable temperature drop this afternoon from east to west, as winds shift from the north into the east with the FROPA. This wind shift will be abrupt, with gusts up to 30 mph from the ENE! This cold air is evident by a pocket of -2C temps at 925 mb advecting down the coast of ME & NH this morning, then into NE MA this afternoon. This chilly airmass will be enhanced by streaming across ocean temps in the low to mid 40s. At the surface, this will translate to a very large temp difference across SNE this afternoon, with highs well into the 60s across western MA/CT, while temps fall into the upper 30s and lower 40s across eastern MA, including Boston and Cape Cod. KEY MESSAGE 2...Showers Saturday night into Sunday, but turning mild Sunday, with highs in the upper 50s and lower 60s. Saturday night...1035 mb surface high over the maritimes, combined with the backdoor front south of New England lifting north as warm front, will set the stage for overrunning precipitation in the form of spotty light rain/drizzle. Chilly with lows in the 30s, then temps rising overnight into the 40s as warm sector approaches from the south. Given the easterly upslope flow up, the eastern slopes of the Berks may experience temps at or below freezing. Hence, some spotty light freezing drizzle can't be completely ruled out. However, given marginal temps and confined to elevation at or above 500 ft, little if any impact expected. Sunday...low pressure over the Great Lakes exits into Ontario, with its trailing cold front sweeping across SNE. Modest jet dynamics coupled with an ample moisture plume (PWATs (Precipitable Waters) 1.2-1.4 inches) will support widespread showers Sunday. Although, given how progressive this system is, expecting modest rainfall totals on the order of 0.2 to 0.4 tenths of an inch, which is supported by both deterministic and ensemble datasets. Hence, beneficial rains but flooding is not expected. Despite the widespread showers, its a mild airmass with dew pts in the 50s. Therefore, not a chilly day with strong low level WAA (Warm Air Advection - the movement of warm air) providing highs in the upper 50s to lower 60s. It will become breezy over RI and eastern MA given the strengthening southwest jet. KEY MESSAGE 3...Could see a few rain/snow showers Monday night/ Tuesday morning, but otherwise expecting cooler temperatures and dry weather for a good portion of next week. Both ensemble and deterministic guidance continue to be in good agreement that an upper-level trough pushes across the Great Lakes and into New England next week, leading to mostly dry weather but cooler temperatures. Ensemble guidance is indicating 850mb temperatures could get to below -5C and 500mb temperatures below - 30C Tuesday as a shortwave moves through, which would support snow showers developing and mixing in with rain showers. Given that surface temperatures will remain at least in the mid 40s, not expecting any road or travel impacts. Otherwise, dry weather with high temps mainly in the middle 40s to the lower 50s and overnight temperatures ranging from the mid 20s to mid 30s through Wednesday night. KEY MESSAGE 4...Second half of next week looks mainly dry with temperatures on the rise. A large high pressure system moves into the Mid-Atlantic region by the second half of next week, bringing predominantly southwesterly flow back to southern New England. The warmer airmass advecting into the region will allow temperatures to recover back into the 50s, likely the 60s, by the end of the week. Expecting conditions to remain mostly dry. Marine Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. High confidence. Given NE/E gusts are currently in very solid SCA (Small Craft Advisory) to near-gale- force range with the immediate passage of the backdoor front, and that SWly gusts for Sunday look to be more in the SCA (Small Craft Advisory) range with strongly- inverted profiles, have hoisted SCAs (Small Craft Advisories) for all waters starting now through 00z Monday (thus, gale watches on southern waters converted to SCAs). Expect gusts to be strongest thru Saturday afternoon at around 25-30 kt (occasional gusts to 35 kt possible), then settle in around 25-30 kt range. Seas remain in the 3-5 ft range thru tonight, then increase more markedly as southerly winds increase the fetch, building offshore to nearly 10 ft on southern waters. Winds Sunday night to shift to NW at sub-SCA (Small Craft Advisory) levels briefly, but could gust to around SCA (Small Craft Advisory) ranges late overnight Monday. Low chance at mist/fog overnight, but better chance for rain showers late Sunday afternoon to early Sunday evening. Outlook /Sunday Night through Wednesday/... Sunday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers. Monday: Winds less than 25 kt. Local rough seas. Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday: Winds less than 25 kt. Chance of rain showers, chance of snow showers. Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine Gale Watch from Sunday morning through Sunday afternoon for ANZ231>235-237-254>256. Small Craft Advisory until 1pm EDT this afternoon for ANZ254>256. |
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