Marine Weather Net

Provincetown MA to Chatham MA to Nantucket MA out 20 NM Marine Forecast


TONIGHT

SE
WINDS
5 - 10
KNOTS

THU

E
WINDS
10 - 15
KNOTS

THU NIGHT

E
WINDS
10 - 15
KNOTS

FRI

E
WINDS
10
KNOTS

The Marine Weather Forecast In Detail:
ANZ254 Forecast Issued: 701 PM EDT Wed Apr 17 2024

Tonight...Se Winds 5 To 10 Kt. Seas 2 To 3 Ft. Wave Detail: Se 3 Ft At 8 Seconds And N 1 Ft At 4 Seconds.
Thu...E Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. Wave Detail: E 2 Ft At 3 Seconds And Se 2 Ft At 7 Seconds.
Thu Night...E Winds 10 To 15 Kt, Diminishing To 5 To 10 Kt After Midnight. Seas 2 To 4 Ft. Wave Detail: E 2 Ft At 4 Seconds And S 2 Ft At 7 Seconds.
Fri...E Winds Around 10 Kt. Seas 3 To 4 Ft. Wave Detail: E 2 Ft At 5 Seconds And E 2 Ft At 11 Seconds.
Fri Night...S Winds Around 10 Kt. Seas Around 3 Ft. Wave Detail: Se 3 Ft At 5 Seconds And E 2 Ft At 11 Seconds.
Sat...Sw Winds Around 10 Kt. Seas Around 3 Ft. Wave Detail: S 3 Ft At 4 Seconds And E 2 Ft At 11 Seconds. A Chance Of Showers.
Sat Night...W Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 3 To 4 Ft.
Sun Through Mon...W Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 4 Ft.
Mon Night...S Winds Around 10 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
651pm EDT Wednesday April 17 2024

Synopsis
Increasing cloud coverage this afternoon, rain chances increase during the overnight hours mainly across western Massachusetts and northern Connecticut. Cloudy, much cooler, with scattered light rain continuing for Thursday. Dry and seasonable for much of Friday with high pressure in control. A cold front brings another round of light rain showers Friday night into Saturday morning. Dry for the rest of Saturday with gusty winds. The dry stretch of weather continues into early next week with the next chance of wet weather Tuesday night and Wednesday as a frontal system approaches.

Near Term - Until 6am Thursday Morning
650 PM

Band of showers along the 850 mb warm front moving through western CT and SW MA. This boundary forecast to only make minor progress east to vcnty ORE-ORH-PVD tonight with best moisture and lift along and west of this area across western MA and northern CT where bulk of rainfall will be. Generally around 0.10-0.25" rainfall here with locally up to 0.5" in western CT where some elevated instability may contribute to some brief heavier downpours. Further E, expect rain area to erode as it moves into eastern MA where considerably drier air resides below 850 mb. As a result, not expecting much more than perhaps a few light showers across eastern MA.

Previous discussion... Highlights:

* Showers likely for areas west of KORE, KORH, and KPVD. Outside of a spot shower, much of eastern Massachusetts remains dry overnight.

Another great day across southern New England, but now the clouds are on the return ahead of a mid-level warm front. Showers and a few thunderstorms are extending in a line from Lake Ontario and points southeast to the New Jersey coast. This activity lifts northeast, arriving across southwest Connecticut and nearing the Hartford and Springfield metros this evening, post sunset. The eastern extent of the precipitation will be limited, as the mid-level warm front encounters drier air mass, the 12Z high-res models and CAMs do show this, with the eastern extent along a line from KORE, KORH, KPVD. While a spot shower east is possible, the area with the greatest likelihood of any appreciable rain will be areas west. Notably, the newer model run of the HRRR (High-Resolution Rapid Refresh) are looking less impressive in terms of areal coverage. Nevertheless, no adverse conditions are expected from these showers.

Increased overnight cloud cover hold temperatures in the lower and middle 40s. Light winds become easterly heading towards day break.

Short Term - 6am Thursday Morning Through Thursday Night
Highlights:

* An easterly wind will lead to a much cooler day, a few showers are possible, though a washout is not expected.

Mid-level ridge for Thursday, though a shortwave passage will bring our a few showers, not a washout by any means. At this point, kept POPs around 30 ~ Chance Rain. The more noticeable difference is the east wind, allowing for a raw/cool feel. High temperatures along the immediate coast are in the middle to upper 40s. Elsewhere, highs are lower and middle 502. Higher elevations in western Massachusetts are the coldest in the lower 40s.

East wind are 10 to 15 mph, with gusts along the coast to 25 mph.

Precipitation chances come to an end overnight, though clouds and on shore flow does continue into the overnight hours. Do think spots along the eastern coast could see spot drizzle, but didn't have the confidence to include it in the WX GRID. Guidance this afternoon remained split on how much low level moisture would linger, so OPT to leave it out. Similar to the night before, our temperatures are in the upper 30s and low 40s.

Long Term - Friday Through Wednesday
Key Points... * Mainly dry and seasonable Friday

* Scattered showers Fri night into early Sat followed by mild and breezy conditions Sat afternoon

* Dry conditions return for Sunday into Tue. Cooler Sun, then milder Monday and Tuesday

* Shower chances increase by Wed

Details... Friday into Saturday... Mid level shortwave departs by early Fri with weak shortwave ridging following. This will bring dry conditions for much of the day, although next shortwave and cold front will be approaching from western NY in the afternoon. We should see some sunshine develop, especially in eastern New England but trend will be for increasing cloud cover in the afternoon. Low risk a few showers could spill into western MA by days end but bulk of shower activity should hold off until Fri night. Near normal temps Fri.

Weak cold front moves into SNE Fri night with modest increase in moisture as PWATs (Precipitable Waters) increase to near 1" ahead of the front. This should bring a round of scattered showers Fri night which will likely linger into Sat morning, especially in the east as the front gets hung up near the coast. Then drying out in the afternoon with somewhat gusty W winds developing in the afternoon. Given the colder airmass will be lagging to the NW assocd with a secondary cold front, it should be a mild afternoon with temps reaching the 60s, and some upper 60s possible in SE MA.

This secondary cold front is tied to a decent shortwave passage late Sat-Sat evening. The column is drying at this time but there may be a brief window for a few showers with the front late Sat in the interior. Did not include in the forecast at this time as confidence is low, but will re-evaluate in later forecasts.

Sunday through Wednesday... Cooler post-frontal airmass settles in on Sunday with seasonable temps and abundant sunshine. Dry weather continues Monday and Tuesday with moderating temps. A potent shortwave is forecast to move off the mid Atlantic coast Monday night-Tuesday but global ensemble guidance keeps moisture well to the south with a minimum in PWATs (Precipitable Waters) across SNE. Next northern stream shortwave approaches from the west Tuesday night and Wed. Timing and amplitude of the system is uncertain but risk for showers will increase by Wed.

Marine
Forecaster Confidence Levels:

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

Tonight through Thursday Night...High Confidence.

* Small Craft Advisory for Block Island Sounds and waters south of Block Island tonight and into Thursday.

A weak wave of low pressure drops southeast across the mid- Atlantic with high pressure moving across the eastern Canadian Maritimes into Thursday. A few spot showers and perhaps a rumble of thunder possible. This will result in SE winds this evening shifting to the E by Thursday morning at speeds of 10 to 15 knots. Some gusts up to 25 knots with marginal 5 foot seas for the southwest waters, hence the newly issued Small Craft Advisory through much of Thursday. Seas may remain elevated enough to warrant the advisory to be extended into Thursday night for the waters south of Block Island. Future forecasts may want to include this.

Outlook /Friday through Monday/... Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers.
Saturday: Winds less than 25 kt. Chance of rain showers.
Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft.

Sunday through Monday: Winds less than 25 kt.

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...None. RI...None.

Marine
Small Craft Advisory from 5am to 5pm EDT Thursday for ANZ237. Small Craft Advisory from 5am to 8pm EDT Thursday for ANZ256.