Coastal Waters out 25 NM South of Marthas Vineyard and Nantucket Marine Forecast
|This Afternoon...N Winds 20 To 25 Kt With Gusts Up To 30 Kt. Seas 7 To 10 Ft, Except 10 To 15 Ft S And E Of Nantucket. A Chance Of Drizzle.|
|Tonight...N Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 6 To 9 Ft, Except 9 To 13 Ft S And E Of Nantucket.|
|Fri...Ne Winds Around 15 Kt With Gusts Up To 20 Kt. Seas 6 To 9 Ft.|
|Fri Night...E Winds 15 To 20 Kt, Increasing To 20 To 25 Kt After Midnight. Gusts Up To 30 Kt. Seas 6 To 9 Ft. A Chance Of Showers.|
|Sat...E Winds 20 To 25 Kt With Gusts Up To 35 Kt. Seas 7 To 10 Ft. Showers.|
|Sat Night...Se Winds 15 To 20 Kt, Becoming Sw 10 To 15 Kt After Midnight. Gusts Up To 30 Kt. Seas 7 To 10 Ft. Showers Likely.|
|Sun...Sw Winds 10 To 15 Kt. Seas 5 To 8 Ft. A Chance Of Showers.|
|Sun Night Through Mon Night...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 4 To 7 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
1009am EDT Thu Oct 28 2021
Much quieter and mainly dry weather returns today into at least part of Friday. A period of rain along with gusty winds is likely sometime from Friday afternoon into Saturday. Dry and seasonable conditions return for Halloween Sunday and the start of November.
Near Term - Until 6pm This Evening
Low pressure well E of New England will continue.nue to pull further away as high pressure builds to the north. Relaxing gradient will result in gradual diminishing winds over the Cape/Islands but still expect 20-30 mph gusts into the afternoon, with gusts below 20 mph elsewhere in eastern MA.
Drier air working in from the north and west will allow for partial sunshine to develop across the interior, but NE flow will maintain abundant low level moisture below the inversion across much of eastern MA/RI where low clouds will linger through the day. Some patchy drizzle is possible over the Cape/Islands.
Highs will be mostly around 50 to lower 50s across region with mid 50s in the CT valley where most sunshine expected.
Short Term - 6pm This Evening Through 6pm Friday
Our region is in between the high pressure over southern Canada and a low pressure moving into the Ohio River valley and the central Appalachians tonight into Friday. Drying trend continues tonight, but only briefly. We could be dealing with an approaching low pressure by late in the day Friday.
Near to slightly below normal temperatures expected. It is possible that low temperatures could be lower than currently forecast should there be less cloudiness. Thinking the shallow moisture layer is still present tonight.
Long Term - Friday Night Through Wednesday
Highlights... * A coastal low brings a period of rain and gusty winds Friday night into Saturday. * Showers may linger into the first part of Sunday but it should be dry for trick-or-treating. * Dry and seasonable weather to start November. * Next chance of rain arrives late Tuesday into Wednesday.
Details... Friday night and Saturday... Another wave of low pressure will approach from the southwest Friday night into Saturday. At the upper levels, an amplifying closed low will lead to enhanced southerly flow out ahead of the next impulse, with dew points briefing getting into the upper 50s/low 60s and PWATs (Precipitable Waters) jumping to almost 1.5 inches, or near the max moving average of Storm Prediction Center sounding climatology for Chatham, MA. Given the dynamics and low level jet, should see a wide swath of 1-2 inches of rainfall. Rain shield moves into our area during the pre-dawn hours from the southwest and spreads northeast during the day. The soaking rainfall will unfortunately make it a washout for the first half of the weekend along with gusty conditions. In addition, a rumble or two of thunder also cannot be ruled out, especially for areas along the south coast as guidance hints at a few hundred joules of CAPE Saturday afternoon into evening.
That said, the wind field and dynamics are not nearly as impressive as the Nor'easter earlier in the week. In fact, while the GFS and EC ensemble guidance tracks the low pressure near the 70W/40N benchmark, the low pressure center does not drop below 1000mb (as opposed to sub-980mb for the recent Nor'easter). And taking into consideration the progressive nature, the primary concern appears to be localized urban and poor drainage flooding. At worst, local creeks could reach bankfull given that grounds are saturated from recent rainfall but overall, not expecting significant flooding concerns given how progressive the system is expected to be. As for winds, ensemble guidance indicates a pretty decent 35-45 kt low level jet. But unlike the powerful Nor'easter that we just experienced, the prevailing wind will be from the southeast, which is generally an unfavorable direction for efficient mixing. Nonetheless, used the NBM 90th percentile to bump up winds to low- end gale force for coastal zones to hint at the potential. Unfortunately, gusty conditions especially on Saturday into Saturday night may hinder power restoration efforts in communities hit hard by the recent Nor'easter.
Sunday/Halloween into Wednesday... While there may be some showers lingering into Sunday morning, it does look like Sunday should be the pick of the weekend with above normal highs in the low to mid 60s and a mix of sun and clouds. It should be a decent evening with dry conditions for the trick-or- treaters. The dry weather continues into Monday as ridging builds in and the flow turns westerly, which allows the low-levels to dry out. So expect the return of sunshine along with dry weather and slightly above normal temperatures in the upper 50s to mid 60s as we turn the calendar into November. Tuesday looks to be a tad cooler than Monday but dry conditions should continue out ahead of a cold front approaching from the west. Shower chances increase by late Tuesday into Wednesday but it remains to be seen whether we get a glancing blow or a more significant rainfall if a secondary low develops. Still plenty of time to figure out the specifics.
Forecaster Confidence Levels.
Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.
Winds continue to diminish. Gale headlines remain in place across most of the waters early this morning. Expecting these will be converted to Small Craft Advisories over time today. Made some last second adjustments based on the latest observed trends. Rough seas will take longer to subside, especially across the outer coastal waters.
Outlook /Friday Night through Monday/... Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft. Chance of rain showers.
Saturday: Moderate risk for gale force winds with gusts up to 35 kt. Rough seas up to 11 ft. Rain showers.
Saturday Night: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 11 ft. Chance of rain showers.
Sunday: Winds less than 25 kt. Rough seas up to 9 ft. Slight chance of rain showers.
Sunday Night through Monday: Winds less than 25 kt. Areas of rough seas.
Tides / Coastal Flooding
Persistent northerly flow prevented efficient drainage of Nantucket Harbor. Latest observations indicated about a 3 foot surge still lingering there. Coastal flood Warning issued for the morning high tide, but will likely need headlines for the afternoon high tide as well.
NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...Coastal Flood Advisory from 5pm this afternoon to 8pm EDT this evening for MAZ024. RI...None.
Small Craft Advisory until 1am EDT Friday for ANZ232>235-237. Small Craft Advisory until 4pm EDT this afternoon for ANZ230. Small Craft Advisory until 8pm EDT Friday for ANZ231-250-251- 254>256. Small Craft Advisory until 1pm EDT this afternoon for ANZ236.