Marine Weather Net

Massachusetts Bay and Ipswich Bay Marine Forecast


THIS AFTERNOON

NE
WINDS
15
KNOTS

TONIGHT

NE
WINDS
10 - 15
KNOTS

MON

NE
WINDS
10 - 15
KNOTS

MON NIGHT

NE
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ251 Forecast Issued: 116 PM EDT Sun Apr 11 2021

This Afternoon...Ne Winds Around 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Patchy Fog. Vsby 1 Nm Or Less.
Tonight...Ne Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Patchy Fog. Vsby 1 To 3 Nm.
Mon...Ne Winds 10 To 15 Kt, Increasing To 15 To 20 Kt In The Afternoon. Gusts Up To 25 Kt. Seas 3 To 5 Ft.
Mon Night...Ne Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Evening. Seas 3 To 5 Ft.
Tue And Tue Night...Ne Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 3 To 5 Ft. A Chance Of Showers.
Wed...Ne Winds 10 To 15 Kt. Seas 3 To 4 Ft. A Chance Of Showers.
Wed Night...N Winds 5 To 10 Kt. Seas 2 To 3 Ft.
Thu...Ne Winds Around 10 Kt With Gusts Up To 20 Kt. Seas 2 To 4 Ft. A Chance Of Showers.
Thu Night...Ne Winds Around 10 Kt With Gusts Up To 20 Kt. Seas 4 To 6 Ft. A Chance Of Showers. 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
1021am EDT Sunday April 11 2021

Synopsis
A backdoor cool front advances through Southern New England this morning, spreading cloudy skies cooler onshore flow across the region today into Monday. Meanwhile, a frontal system passing to our west will also bring a period of light rain for the interior later today. Two weather systems pass Southern New England, one on Tuesday and the other Thursday- Friday. Each will bring showers, but with light amounts.

Near Term - Until 6pm This Evening
1015 AM

Let the Dense Fog Advisory expire as vsby has improved. Mesowest obs shows the backdoor cold front reach the CT River valley with Day Cloud Phase satellite imagery showing the associated low stratus well. Forecast remains largely on track. Main change with this update was to bump up temps along the CT River valley given the partial clearing (a narrow time frame between mid level clouds pivoting in from the west and the low stratus moving in from the east) and the fact that it doesn't take much sunshine in mid April for temps to pop. Also lowered the Probability of Precipitation given current radar trends, with better forcing for meaningful precipitation remaining to our south and west. Overall, it will be a rather raw and dreary day with the occasional mist and drizzle after the anomalous warm stretch of weather. However, for perspective, the normal highs for this time of the year is in the mid to upper 50s. So we are actually right about average for this time of the year.

PREVIOUS

645 AM Backdoor cold front at 6am had moved through Boston Metro-west area. May take until midday to get through the remainder of Srn New England. Observations showed lots of low clouds and areas of fog. The fog will thin out, but the clouds will linger for a few days.

No significant changes to the forecast. Continue to expect the dense fog along the South Coast to thin around 10am or a little after.

We hope you had an opportunity to enjoy the sunny and mild weather pattern over the last handful of days. Starting today, a pattern change towards cloudier, cooler and frankly downright raw weather conditions takes hold of Southern New England at least into early in the workweek.

Several features of note this morning. Weak high pressure is still producing SW winds across most of Southern New England. This is allowing for still quite mild temperatures away from the southern coastline with temperatures in the mid 50s! SW winds have also permitted locally dense fog to return back northward across the South Coast into Cape Cod, the Islands and adjacent waters. Given visibility observations and after coordination with NWS New York, a dense fog advisory has been hoisted thru 14z for southern RI into coastal SE MA and Cape Cod/Islands. The primary feature of interest is a backdoor cold front which now extends from Laconia- Concord- Manchester-Nashua line in NH on just south of Lawrence and Beverly in MA. The front is pretty clearly evident in METARs with a stratus field apparent in nighttime microphysics RGB imagery into these same areas. Fairly substantial airmass change lies behind the front - temperatures at Beverly fell some 10 degrees between 06 to 07z and winds flipped to NE upon its passage. The other notable feature, more so for later today into tonight, is a closed upper low over southern MI which has a NW- SE oriented rain shield from NW PA southeast into the Delmarva Peninsula.

So for today, we are looking for increasing clouds which will mainly be in the form of stratus, along with cooling temperatures and lowering dewpoints. Winds will also shift to NE and increase with speeds increasing to around 10-15 mph. This will occur as the backdoor front surges southwestward across Southern New England. The air mass change will be quite noticeable, and certainly compared to the last few days where many areas were in the 60s to the 70s. There may be a few hours of some heating to offset this across western MA and parts of northern CT. However many areas will see hovering to falling temperatures through most of if not all of today. Have again utilized higher-res guidance to best capture the expected fall in temperatures. This translates to early-day highs across eastern and central MA into much of RI, and highs occurring around late morning to midday across western MA into northern CT in the upper 50s to lower 60s before falling. Upon passage of the backdoor front in eastern/central MA into RI, most areas will struggle to reach 50 degrees. The onshore winds will also make for a rather raw day.

Late in the day, the rain shield now over the mid-Atlantic into the eastern Gt Lakes progresses NE into CT and into western MA. Soundings again show some dry mid-level air that needs to be overcome first, but have offered Probability of Precipitation increase into the solid Likely range between 5-7pm here, while areas along and northeast of a Worcester to Providence to Newport line may be tough to see much of any precip. Probability of Precipitation decrease to the NE into the Chance to Slight Chance range.

Short Term - 6pm This Evening Through 6pm Monday
Tonight into Monday:

In essence, really more of the same general raw and cloudy conditions. Shallow PBL cooling continues to take place which will help to lock in areas of stratus and mist, along with slowly cooling temperatures. Some differences in the models with regard to how the evolution of the rain shield is handled. Most of the synoptic models more or less fractures the band as it tries to lift northeast, but the higher res guidance sends the steadiest rains on northeast into NH/ME. Stuck with the synoptic models depiction with rains more or less confined to our western and southwestern areas with Probability of Precipitation more in the Chance range. Slow cooling down to rather uniform lows into the low to mid 40s, with a continued though lighter easterly onshore wind.

Still cloudier than not for Monday, but there is some optimism early in the day for some breaks in clouds (towards more broken lower clouds). However a reinforcing backdoor front and renewed enhancement to onshore flow should again allow for lower clouds to fill back in into the afternoon. In addition, as the closed low over the eastern Gt Lakes moves east, it may induce another period of steadier rains across western MA into northern CT. Temperatures will again struggle to climb much if at all - in fact the 3-hourly temps on the MAV/MET guidance show maybe a degree or two of warming if any occur at all. Thus, looking for highs in the mid to upper 40s, perhaps near 50 in the CT Valley. East to northeast winds will pick up again to speeds around 10-15 mph with strengthening easterly pressure gradient.

Long Term - Monday Night Through Saturday
Big Picture... A series of closed upper lows stretch across the USA Northern Tier, but dominated by one closed low over the Great Lakes. A part of this upper low ejects south of New England Tuesday. The bulk of the system over the Great Lakes then moves east over the Northeast USA late in the week. An upper ridge then builds from the Southern Plains into the Northeast and bringing drier weather for the weekend.

Upper contours are forecast below long-term normal midweek, then trend to normal by late week. Surface flow varies between northeast and north during this time, reinforcing the expected cold pattern midweek that moderates to around normal late week.

The various model mass fields are similar through midweek, but then diverge late week. Forecast confidence is low-moderate.

Details... Monday night through Wednesday... Surface low associated with the ejecting fragment from the Great Lakes low moves south of New England. This maintains the low-level northeast flow...a marine flow...over Eastern MA and RI. The position of this coastal upper low favors a few showers over Western MA, Northern CT, and parts of RI. The northeast flow favors scattered showers over Eastern MA. Put it together, it suggests a period of scattered showers. Although Quantitative Precipitation Forecast placement varies model-to- model, all clearly indicate light precip...generally less than one- tenth inch.

The coastal system moves off to the southeast on Wednesday. Lingering showers in the morning should diminish...will indicate slight chance probability of precipitation in the afternoon.

Mixing profiles are shallow Tuesday and Wednesday. This suggests Tuesday highs upper 40s near the east coast and lower 50s inland...Wednesday highs in the 50s. Low level temps are consistent with mins in the upper 30s and low 40s.

Thursday through Saturday... The Great Lakes upper low ejects southeast to the Mid-Atlantic coast. The 00Z ECMWF (European Centre for Medium-Range Weather Forecasts) shows significant rainfall Thursday and Friday. The 00Z GFS shows lighter precipitation over us and heavier amounts staying offshore to the south. The GFS also shows an intense surface system spinning up with a tight pressure gradient over the ocean waters to our south, but a lighter gradient over Srn New England. GFS shows northeast winds of 40-50 kt between 900 and 950 mb, supporting wind gusts of 25-30 kt. Blending the precipitation suggests a chance of showers both Thursday and Friday with the best chance in areas south of the Mass Pike.

The system pulls away during Friday. Eastern Canada high pressure then builds in with dry weather for Saturday.

Marine
Small craft advisories remain in effect for later today into Monday on the southern offshore waters, as seas project to build to 5-6 ft and easterly flow becomes enhanced. SCAs (Small Craft Advisories) will also need to be considered for Monday as building seas over a generally persistent easterly fetch should bring SCA (Small Craft Advisory) conditions to the eastern waters as well.

Initial SW winds will transition to NE and increase to speeds 10-15 kt with gusts in the low-20s kt from N to S today. Seas generally in the 2-4 ft range for most waters except 5-6 ft on the southern offshore waters.

For tonight, expect a decrease in NE/E winds on the eastern waters to around 15 kt gusts, while gusts on the southern offshore waters should reach into the lower-end SCA (Small Craft Advisory) levels (25 to near 30 kt). Seas 2-3 ft eastern waters, increasing to 5-7 ft on the southern offshore waters.

Into Monday, enhancement to NE/E flow should bring gusts to near or over SCA (Small Craft Advisory) levels on most waters. Seas will also build further into the 5-7 ft range offshore and around 2-4 ft nearshore.

Outlook /Monday Night through Thursday/... Monday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers.
Tuesday through Tuesday Night: Winds less than 25 kt. Local rough seas. Chance of rain showers.
Wednesday through Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...None. RI...None.
MARINE...
Small Craft Advisory from 5pm this afternoon to 8pm EDT Monday for ANZ254>256.