Marine Weather Net

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


10 - 15


5 - 10


10 - 15


10 - 15

The Marine Weather Forecast In Detail:
ANZ254 Forecast Issued: 401 AM EDT Wed Sep 28 2022

Today...W Winds 10 To 15 Kt. Gusts Up To 20 Kt This Afternoon. Seas 3 To 5 Ft.
Tonight...W Winds 5 To 10 Kt, Becoming N 10 To 15 Kt After Midnight. Seas 3 To 4 Ft.
Thu...N Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Afternoon. Seas 3 To 4 Ft.
Thu Night...Ne Winds 10 To 15 Kt. Seas 3 To 4 Ft.
Fri...Ne Winds 10 To 15 Kt. Seas 3 To 4 Ft.
Fri Night...E Winds 5 To 10 Kt, Becoming Se After Midnight. Seas 2 To 3 Ft.
Sat...E Winds Around 5 Kt. Seas 2 To 3 Ft.
Sat Night...E Winds 5 To 10 Kt. Seas 2 To 3 Ft. A Chance Of Showers.
Sun...Ne Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 4 To 6 Ft. A Chance Of Showers.
Sun Night...Ne Winds Around 20 Kt With Gusts Up To 30 Kt. Seas 5 To 8 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
300am EDT Wednesday September 28 2022

Mainly dry and seasonable conditions today, then cooler Thursday and Friday but remaining dry as a large high pressure builds into New England. Still uncertain how far north the rain from Ian gets this weekend, but the best chance of showers is near the south coast Saturday night into Sunday. The remnants of Ian are expected to move off the mid Atlantic coast early next week with rain lurking just offshore.

Near Term - Until 6pm This Evening
Mid level trough slides eastward today from the eastern Lakes with cold pool(a region of relatively cold air) aloft spreading across much of interior SNE. This will lead to more diurnal cu developing with greatest coverage across the interior where a spot shower is possible. Warmer temps aloft near the south coast where less cu field, but expect increasing cirrus assocd with 140-150 kt upper level jet.

Winds more westerly today with generally W/NW flow but less gustiness. Deep boundary layer mixing and partial sunshine will support highs in the upper 60s to lower 70s, a few degs cooler than Tue, but right on track for late Sep.

Short Term - 6pm This Evening Through 6pm Thursday
Tonight... Trough axis slides east into SNE overnight but the column is dry so dry weather will prevail with just some mid/high clouds. Weak surface front/trough across SE New England in the evening moves offshore with a wind shift to N as strong high pressure builds across the Great Lakes. Lows mid/upper 40s, except low/mid 50s urban areas and along the coast.

Thursday... Strong high pressure sets up from the Gt Lakes to northern New England with cooler N/NE flow into SNE. The mid level trough axis and cold pool(a region of relatively cold air) aloft will be over the region so more diurnal cu expected to develop. But continued dry conditions as even drier air advects southward into SNE with PWATs (Precipitable Waters) decreasing to less than 0.5". The N/NE flow and cooling low levels will keep highs in the 60s.

Long Term - Thursday Night Through Tuesday
Highlights... * Cool temperatures throughout, with highs generally in the 60s.

* Mostly dry weather, but rain chances return Saturday night/Sunday, mainly along the south coast.

* Breezy winds Sunday and Monday.

Details... Overall a quiet stretch of weather through the weekend, with the only potential hiccup being the remnants of Hurricane Ian making their way north by Sunday/Monday. Zonal steering flow remains overhead Thursday night through Sunday, while at the surface a series of high pressures dominates the weather pattern. This will keep temperatures cool, a bit below normal for late September thanks to prolonged north/northeast flow. Highs on Friday will be in the mid to upper 60s before our "warmest" day of the period on Saturday when some locations may reach 70F. A reinforcing shot of cold air arrives with a moisture starved cold front which will bring highs in the low 60s and even the upper 50s in the highest elevations by Monday. Lows will generally be in the 40s, though good radiational cooling on Thursday night will allow far NW interior locations to drop into the mid-upper 30s, so frost headlines may be necessary.

By Sunday into the start of next week high pressure moves overhead from the midwest which will likely help keep the remnant moisture from Ian mainly south of us. Best shot at rain showers will be for coastal RI and southern MA Saturday night into Sunday, while the increased pressure gradient bring gusty northeast winds. The extended period of gusty NE winds Sun-Monday will lead to rough seas and potential for some minor coastal erosion issues for the afternoon high tides; fortunately astronomical tides will be on their way down, but something to keep an eye on. Our next shot at rain comes Monday night or Tuesday with the arrival of a mid level shortwave and surface low passing offshore.

Forecaster Confidence Levels:

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

Today through Thu... Lingering 5 ft seas over southern waters will subside this morning with seas below SCA (Small Craft Advisory) through Thu. W wind gusts to 15-20 kt today shifting to N around or after midnight, then N/NE gusts 15-20 kt Thu. Dry weather and good vsby prevail thru the period.

Outlook /Thursday Night through Sunday/... Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday through Friday Night: Winds less than 25 kt.

Saturday: Winds less than 25 kt. Slight chance of rain showers.
Saturday Night: Winds less than 25 kt. Chance of rain showers.
Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain showers.

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