Marine Weather Net

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


TONIGHT

NW
WINDS
5 - 10
KNOTS

SUN

NW
WINDS
10 - 15
KNOTS

SUN NIGHT

SW
WINDS
5 - 10
KNOTS

MON

S
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ254 Forecast Issued: 727 PM EDT Sat Oct 23 2021

Tonight...Nw Winds 5 To 10 Kt, Increasing To 10 To 15 Kt After Midnight. Gusts Up To 20 Kt. Seas 2 To 4 Ft. A Slight Chance Of Showers.
Sun...Nw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft.
Sun Night...Sw Winds 5 To 10 Kt. Gusts Up To 20 Kt In The Evening. Seas 2 To 4 Ft. A Chance Of Rain.
Mon...S Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Rain Likely.
Mon Night...S Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 4 To 6 Ft. Rain Likely. Vsby 1 To 3 Nm.
Tue...Se Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 6 To 9 Ft. Rain Likely. Vsby 1 To 3 Nm.
Tue Night...E Winds Around 15 Kt With Gusts Up To 30 Kt. Seas 7 To 10 Ft. Rain Likely.
Wed...Ne Winds Around 15 Kt With Gusts Up To 25 Kt. Seas 9 To 12 Ft. Rain Likely.
Wed Night Through Thu Night...Ne Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 9 To 12 Ft. A Chance Of Rain. 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
730pm EDT Sat Oct 23 2021

Synopsis
Seasonably cool and dry through Sunday afternoon. A slow moving weather system will bring a rather unsettled/wet weather pattern at times for the upcoming week; beginning late Sunday night. The risk for heavy rain along with nuisance poor drainage street flooding is possible late Monday night into Tuesday.

Near Term - Until 6am Sunday Morning
630 PM

Previous forecast remains on track. Weak short-wave propagating over the south coastal waters is producing some light returns on radar. Should see a few sprinkles mainly over the islands over the next couple of hours before skies start to clear out after midnight. See previous discussion for additional details.

Previous Discussion. A moisture starved shortwave will move across the southern portion of our region this evening. It will result in mainly a period of cloudiness, but a brief sprinkle/spot shower or two across CT and areas near the south coast roughly between 8 pm and 2 am. Otherwise, across the rest of the region except mainly clear skies with light winds for most of the night. This coupled with a dry airmass in place will allow for a good night of radiational cooling. Low temperatures will bottom out mainly in the middle 30s to the lower 40s. This will result in areas of frost in the typically prone areas. We did expand the Frost Advisory into our zones that were still active.

Short Term - 6am Sunday Morning Through Sunday Night
Highlights... * Dry weather on Sunday with seasonably temperatures * Rain overspreads from west to east Sunday night between 10pm & 3 AM

Details... Sunday... A brief ridge of high pressure will result in dry/pleasant weather continuing into Sunday. Light winds along with plenty of sunshine will result in a very comfortable afternoon. We should see some mid- high level cloudiness increase from the west by late in the afternoon, but will not have much of an impact. 850T around 0C will result in seasonable temperatures with highs in the upper 50s to near 60.

Sunday night... Clouds will be on the increase and also thicken up Sunday evening in advance of a wave of low pressure. This will induce a modest southwest LLJ of 40-50 knots riding over cool shallow in version in the boundary layer. This will result in a band of mid level lift inducing a period of widespread rain developing. Time of arrival is roughly between 10 pm and 3 am from southwest to northeast. The heavier rain should setup north of the south coast and particularly in northern MA where the better forcing resides. Low temperatures should mainly be in the 40s.

Long Term - Monday Through Saturday
Highlights

* Wet and unsettled pattern next week * Several inches of rain expected for southern New England by next weekend

Monday through Tuesday Night

The long term forecast will be highlighted by persistent cyclonic flow over the eastern half of the US. The first half of the week will feature a mid-latitude cyclone developing over the Midwest and moving eastward toward southern New England. We'll see a round of rain and showers along an associated warm front that will be situated over southern New England on Monday. May also see a period of strong gusty winds over The South Coast and The Cape as a 40-50 knot low-level jet at 925 hPa moves over the south coastal waters.

More substantial rainfall is forecast Monday night into Tuesday as the low moves off the east coast and intensifies. Model guidance is suggesting that strong frontogenesis will develop over the south coast which will support periods of moderate to heavy rainfall across southern New England on Tuesday. Will need to monitor this time period carefully as we can't rule out precipitation rates capable of producing urban and small stream flooding.

Wednesday and Thursday

By Wednesday morning there is a fair degree of spread in the models with respect to the location of the surface low-pressure center. Consulting ensemble guidance the consensus is for the low to be located just southeast of MVY and ACK. This will continue.nue to support rain/shower chances across southern New England. By this time however, the system will be in decay and rainfall rates should not be as impressive as what we'll see on Tuesday. As the system continues to drift east over the coastal waters on Thursday the interior will see a break in the wet period. The coastal areas however may continue to see some drizzle or light showers as onshore flow persists.

Friday through Sunday

Another low-pressure system develops late week and brings another chance for substantial rain on Friday and next weekend. Gusty winds will again be a possibility as models are hinting at the development of a strong low-level jet over southern New England. Consulting ensemble model guidance, total rainfall between this system and the Monday - Wednesday
stem could reach 3-6 inches for portions of southern New England by Saturday.

Marine
Forecaster Confidence Levels.

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

Tonight and Sunday...High Confidence. A ridge of high pressure will build in from the west tonight into Sunday. This will keep conditions below SCA (Small Craft Advisory) thresholds with winds from the west mainly in the 10 to 15 knot range.

Sunday night...High Confidence. Wave of low pressure will approach from the west along an associated warm front near the south coast. The result will be winds shifting to the E in our northern waters, but generally remaining light through daybreak Mon. Across our southern waters winds should shift to the south and gusts may reach the lower 20 knots by daybreak.

Outlook /Monday through Thursday/... Monday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of rain.

Monday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain.

Tuesday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 10 ft. Rain likely. Local visibility 1 to 3 nm.

Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 11 ft. Rain likely.

Wednesday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 12 ft. Chance of rain.

Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 12 ft. Chance of rain.

Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 12 ft. Chance of rain showers.
NOAA Boston MA Office: Watches - Warnings - Advisories
CT...Frost Advisory from midnight tonight to 8am EDT Sunday for CTZ003-004. MA...Frost Advisory from midnight tonight to 8am EDT Sunday for MAZ005-006-009>011-013-017-018-026. RI...None.

Marine
None.