Siasconset, MA Marine Weather and Tide Forecast

Marine Weather and Tide Forecast for Siasconset, MA

December 9, 2023 9:35 AM EST (14:35 UTC)
Sunrise 6:58AM   Sunset 4:16PM   Moonrise  4:11AM   Moonset 2:55PM 

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ANZ005 604 Am Est Sat Dec 9 2023
Synopsis for eastport me to stonington me out 25 nm.. A warm front approaches today and crosses the region tonight. Intensifying low pressure tracks across maine Monday and will draw a cold front across the region Monday evening. High pressure builds Monday night into Tuesday. A cold front moves through Wednesday.

7 Day Forecast for Marine Location Near Siasconset, MA
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Area Discussion for - Boston, MA
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Area Forecast Discussion National Weather Service Boston/Norton MA 855 AM EST Sat Dec 9 2023

High pressure drifts offshore today, providing dry, tranquil weather to our region. A strong frontal system has the potential to bring a period of heavy rain, strong southerly winds to the entire region, with possible coastal flooding along the south coast. All of this occurring from late Sunday into Monday morning. A few snow showers across northwest Massachusetts are possible Monday afternoon and evening as the system departs.
Otherwise, turning drier Monday evening with a brief shot of colder air, but temperatures look to rebound back closer to seasonable levels Tuesday through Thursday.


High pressure moves offshore today, leading to mainly dry weather through tonight. A warm front is also expected to move through southern New England during this time. Besides the increased temperatures, the main impact will be the increasing clouds this afternoon into tonight. Cannot completely dismiss the idea of a few sprinkles, but there remains a lot of drier air aloft to overcome before precipitation would reach the ground.

Updated: 3:30AM

* Multi-hazardous system Sunday night into Monday bringing damaging wind gusts, flooding rains, coastal flooding concerns, in addition to dangerous marine conditions.

Our confidence continues to increase with the latest round of model guidance that a robust weather system will bring multiple hazards to our region. Those hazards include; damaging winds, coastal flooding, flooding rains, and dangerous marine conditions. During this update there were not many large deviations from the previous issuance as guidance remains in fairly good agreement, outside of a couple minor adjustments that were made now the high-res guidance has began to capture the onset of the storm.

The first-half of Sunday will be a transition period, largely dry, but a few spot showers may develop with WAA. Winds begin to uptick during this time, generally between 15-25 MPH, stronger winds arrive overnight. Afternoon highs climb to the upper-50s and low-60s. The time between mid to late afternoon conditions begin to go down hill.

The second-half of Sunday mid-level heights fall ahead of a robust trough, which digs as far south as the gulf coast. The trough becomes negatively tilted overnight through late Monday morning, which will help the surface low strengthen as it ejects off the coast of the Mid Atlantic. Since last night guidance has backed off, a little bit, on how deep the surface low drops as it moves northeast across the New England states. What continues to remain constant are the strong winds associated with the LLJ. The 925mb LLJ over RI and SE MA remain out of the south between 70 and 80 knots. Across the interior the 925mb winds, from the south are between 40 to 60 knots.

PWATs remain elevated, on average 1.3 inches, though some guidance does support PWAT values at 1.8 inches. Never the less this is an anomolously moist system for early December, 300 to 400 percent of normal, and 4 to 5 standard deviations above normal.

Monday afternoon the surface low exits towards northern Maine, which will shift our winds from south to the west, CAA changes rain to snow across the elevated terrain of western Massachusetts and potentially the northern hills of Worcester County. For what it is worth, the 00z deterministic GFS trended noticeably colder and suggesting potential snow coverage could expand outside of the higher terrain. If confidence grows, snow showers may be added into the forecast across some lower elevations of western Massachusetts and Connecticut.

Now, let's discuss the hazards a bit further:

Damaging Winds - Confidence remains high for strong to damaging wind across southern New England for Sunday night through Monday morning.
A 'High Wind Watch' continues for Cape Cod and the Islands, includes the Elizabeth Islands and Block Island. Greatest challenge are how much of those strong winds associated with the LLJ are going to mix down to the surface. To reiterate, BUFKIT continues to show a low level inversion, which could trap the strongest winds above the ground. Since the strongest winds aloft are across the waters, confidence remained too low to expand the watch any further west.
For what it is worth, the ECMWF ensemble has shifted the max wind gusts down, but still a note worthy 50-80 percent change for max wind gusts over the Cape and Islands to exceed 50 knots. As mentioned before, as we get closer to the event this watch can either be upgraded to a warning or replaced by a 'Wind Advisory'. Do expect there will be areas west of the current watch that do fall under an advisory leading up to Sunday night.

Flooding Rains - Global ensembles are in good agreement rain totals amount between 1 and 2 inches, with the greatest amounts shifting east towards eastern Connecticut, central Massachusetts, and Rhode Island. An extreme, the GFS ensembles have probabilities up to a 30 percent for rainfall exceeding 4 inches from southern Hartford County and northeast to southern Worcester County. A Flood Watch continues for all of northern Connecticut and central to western Massachusetts. We could experience poor drainage due to leaf and debris blocking storm drains and urban flooding. Also, the MMEFS, an ensemble forecast for river flooding does have a few areas mainly across Connecticut and western Massachusetts with a probability of 30 percent area rivers could reach minor flood stage during this event. Lastly, we can not rule out some thunder during the overnight as the possibility is there for a fine line to develop, as this system has more spring-like qualities. 00z CAMs do end 00z Monday so it does not sample the early morning hours when a fine line could occur. We will need to continue to monitor this. For now, did leave mention of thunder in the forecast grids. In the event of thunderstorm development it would become easier to mix those strong winds aloft from the LLJ down to the surface.

Coastal Flooding - This hazard comes with the understanding that high tide would need to occur with the peak storm surge to have the greatest impacts. We remain alert to the Monday morning high tide for the south coast of Rhode Island and southeast Massachusetts. Our greatest confidence in coastal flooding occurring, in and around Narragansett Bay. Here we have a 'Coastal Flood Watch'. There is little change in the guidance so the forecast for coastal flooding has not deviated. If the stronger winds materialize (mix down) they could lead to as much as 3 feet of surge. Then, if that surge coincides with high tide (6:20 am in Providence) it could lead to coastal flooding. At the Fox Point forecast location the mean of flood guidance takes it to around 7 ft (minor flood) but a worse case scenario takes it to near 9 ft (moderate flood). Too soon to know with any certainty but both are in the realm of possibility with this system. Post frontal winds will then kick up during the day on Monday with winds gusting 35-45 mph out of the west.

Marine - Because of the growing confidence of strong gusts over area waters, a 'Storm Watch' remains in effect for gusts over knots or greater. In addition to potential storm force winds, seas off shore build to a height of 12 to 15 feet, while closer to the shore line, waves could be as high as 8 to 12 feet! It is not out of the realm of possibilities there could be coastal erosion along south facing beaches.

The main weather feature to impact southern New England during this portion of the forecast will be a large high pressure over the Central Appalachians and Mid Atlantic. This high pressure should maintain dry weather. Expecting near normal temperatures through mid week, with a slight warming trend late next week.

Forecast Confidence Levels:

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

12Z: TAF forecast remains largely unchanged, there are a few area of patchy fog in western CT and northwest MA. Wanted to add in there is potential for LLWS Sunday morning, 12z-15z, and could be in the range of 30-40 kts. Upcoming TAFs may reflect this if confidence increases.

High Confidence through Tonight. Moderate Confidence Sunday through Monday. High Confidence Monday Night through Wednesday.

Today...VFR cloud bases with dry weather.

Tonight...VFR cloud bases and mainly dry weather. However, trending MVFR in areas of fog and a risk of showers toward 12z Sunday across western MA/CT.

Sunday...Mainly MVFR with areas of IFR across the higher terrain during the morning, trending to more widespread IFR during the afternoon across the western half of southern New England. Strong south winds developing.

Sunday Night and Monday...Strong gusty south winds 35-50 kt Sunday night, shifting west to northwest behind a strong cold front Monday. Poor visibility in widespread rain and isolated thunderstorms. Some snow possible across the east slopes of the Berkshires Monday before precipitation ends from west to east.

KBOS Terminal...Moderate confidence in TAF. Quiet weather through this evening, but there is a low probability that low clouds could bring periods of IFR tonight before the Sunday morning push.

KBDL Terminal...Moderate confidence in TAF. Quiet weather through this evening, but there is a low probability that low clouds could bring periods of IFR tonight before the Sunday morning push.

Outlook /Monday Night through Wednesday/...

Monday: Mainly VFR, with local IFR possible. Strong winds with gusts up to 55 kt. Chance SHRA.

Monday Night: VFR. Strong winds with gusts up to 45 kt.

Tuesday through Tuesday Night: VFR. Breezy.

Wednesday: VFR. Windy with local gusts up to 30 kt.

Forecaster Confidence Levels:

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

High Confidence through tonight.

High pressure moves offshore today, followed by a warm front tonight into Sunday. Areas of fog possible tonight as humidity increases.

The main focus for mariners should be the expected period of dangerous winds and seas Sunday night into Monday. Southerly storm force gusts are the main threat, followed by westerly gale force gusts behind a strong cold front Monday. Poor visibility at times in rainfall. There is even a risk for isolated thunderstorms.

Outlook /Monday Night through Wednesday/...

Monday: Low risk for storm force winds with gusts up to 60 kt.
Rough seas up to 20 ft. Chance of rain showers. Local visibility 1 to 3 nm.

Monday Night: Strong winds with gusts up to 40 kt. Rough seas up to 15 ft.

Tuesday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft.

Tuesday Night through Wednesday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft.

CT...Flood Watch from Sunday afternoon through Monday evening for CTZ002>004.
MA...Flood Watch from Sunday afternoon through Monday evening for MAZ002>004-008>012-026.
High Wind Watch from late Sunday night through Monday afternoon for MAZ022>024.
RI...High Wind Watch from late Sunday night through Monday afternoon for RIZ008.
Coastal Flood Watch from late Sunday night through Monday morning for RIZ002-004>007.
MARINE...Storm Watch from late Sunday night through Monday morning for ANZ230-236.
Storm Watch from late Sunday night through Monday afternoon for ANZ231>235-237-250-251-254>256.

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AirportDistAgeWind ktVisSkyWeatherTempDewPtRHinHg
KACK167 sm42 minSE 1010 smMostly Cloudy46°F43°F87%30.32

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