Nantucket Sound Marine Forecast
|Overnight...Sw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 3 To 4 Ft. Isolated Tstms. A Slight Chance Of Showers, Then Showers Likely.|
|Mon...Sw Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 3 To 4 Ft.|
|Mon Night...Sw Winds 15 To 20 Kt, Diminishing To 10 To 15 Kt After Midnight. Gusts Up To 25 Kt. Seas 2 To 4 Ft.|
|Tue...Sw Winds 10 To 15 Kt. Seas 3 To 4 Ft.|
|Tue Night And Wed...W Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 3 To 4 Ft.|
|Wed Night...Nw Winds 10 To 15 Kt. Seas 2 To 3 Ft.|
|Thu Through Fri Night...E Winds 10 To 15 Kt. Seas 2 To 3 Ft. Winds And Seas Higher In And Near Tstms. 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
941pm EDT Sunday September 25 2022
A warm front will lead to a few showers and thunderstorms towards the south coast this evening. A shallow cold front then follows with drier conditions from west to east after midnight. Pleasant temperatures follow Monday and Tuesday with mainly dry weather, other than a spot shower or two. Temperatures slowly cool off mid week into early next weekend. High uncertainty if moisture from Ian eventually impacts us next weekend or remains to our south.
Near Term - Until 6am Monday Morning
Forecast remains on track. Only made some adjustments to near-term PoPs to reflect latest observed trends. Very little activity on KBOX radar at this hour, but the OKX radar reveals a cluster of showers and thunderstorms over New York City. These showers and storms will make their way over the Long Island sound and perhaps intrude portions of the south coast. Latest Storm Prediction Center mesoanalysis illustrates some instability in these area, but it is expected to wane in the coming hours. Nonetheless, can't rule out a rumble of thunder with some of these showers. Most areas across the interior will stay dry tonight but under cloud skies which will keep temperatures mild in the 50s and 60s.
Short Term - 6am Monday Morning Through Monday Night
Looking for more sunshine to develop during Monday, at least until diurnal clouds start to develop with a persistent cold pool over the Great Lakes. Scattered showers are also expected, mainly towards western MA, which will be closer to the core of the cold pool(a region of relatively cold air) aloft. Not looking like much of a thunderstorm risk at this time.
Clouds and showers should dissipate Monday evening, leaving dry conditions for most through Monday night.
Expecting temperatures to be slightly higher tomorrow with more sunshine during the day. Near to slightly above normal temperatures expected Monday night.
Long Term - Tuesday Through Sunday
Highlights... * A spot shower or two Tuesday, otherwise expect dry conditions through Friday. At this time it is uncertain if the moisture from Ian makes it to southern New England for next weekend.
* Warm Tuesday, seasonable Wednesday, then below normal temperatures for Thursday into next weekend.
Tuesday and Wednesday:
An anomalous mid-level trough across the Great Lakes region on Tuesday will deamplify and move east on Wednesday. Early morning Tuesday a weak surface low exits the waters east of southern New England which allows for a few spot morning showers across eastern Massachusetts, Cape Cod, and the Islands. A secondary low moves northeast from Montreal to Quebec Tuesday into Wednesday as well with a trailing cold front. The lack of deeper moisture/forcing will generally result in a dry frontal passage; other than perhaps a brief spot shower or two. PWATs (Precipitable Waters) are generally less than 1/2 inch.
Southwest winds aloft on Tuesday will advect a warmer air mass into the region, ahead of the front, with temperatures reaching into the low and mid-70s. Slightly cooler in the 60s for elevated communities across western Franklin/Hampshire/and Hampden. Post front winds aloft become west and results in seasonable highs in the mid-60s to near 70 degrees for metrowest Boston.
Thursday and Friday:
Global ensembles continue to support a dry conditions throughout the remainder of the work week with an area of high pressure extending across much of the northeastern United States. In addition, the global ensembles are still showing a signal for below average afternoon temperatures. Therefore, high temperatures mainly are in the 60s Thursday and Friday. The dry airmass in place will result in low temps in the 40s with some 30s in the outlying locations. So would expect to see some bouts of frost by the end of the week.
Saturday and Sunday:
Forecast confidence diminishes considerably by next weekend. Main issue will be Ian and/or its remnants to our south. There remains high uncertainty on whether or not the moisture from Ian will eventually get pulled northward into southern New England. This is quite evident in the latest individual ensemble members from the GEFS/EPS guidance. Some of the members keep the rainfall to our south, while others bring it up into our region. There is not much more that we can say at this time, but we will need a few more days to have a better idea.
Forecaster Confidence Levels:
Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.
A warm front is expected to move into southern New England and across the waters this evening. A cold front should move from west to east after midnight into Monday morning. Gusty SW winds up to 30 kt for some waters, with rough seas developing across the southern coastal waters. Small Craft Advisories continue into Monday. expecting a period of rough seas later tonight for the coastal waters east of Boston later this evening. Winds and seas gradually diminish Monday night.
Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers.
Tuesday Night: Winds less than 25 kt. Seas up to 5 ft.
Wednesday through Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...None. RI...None.
Small Craft Advisory until 4am EDT Monday for ANZ231-250. Small Craft Advisory until 10pm EDT Monday for ANZ232>234. Small Craft Advisory until 4am EDT Tuesday for ANZ235-237. Small Craft Advisory until 8am EDT Tuesday for ANZ254>256.