Set-Up: Moisture is riding up the coast from the southeast early this morning, and the coastal storm will continue to develop as it moves south of New England this weekend. In fact, latest indications are that the storm will move even further south of the area than I anticipated with my initial forecast Thursday night.
Timing: The first wave of moisture will be light as it arrives around Greater Boston late this afternoon and evening. Winds will remain out of the east today and really into tonight as well, so much of this precipitation will be falling as rain, or at best a mixture of rain and wet snow, along the coast and for areas near and south of Boston. North of Mass Pike and away from the coast the precipitation late today and tonight will fall as wet snow.
While the precipitation around Boston, and even on the South Shore, may flip to wet snow overnight as winds turn to more of a northerly direction and temperatures cool, I think we’ll still have rain mixing in at times right through the day on Sunday for much of Greater Boston.
A final shot of moisture will move through Greater Boston Sunday night, and by that time temperatures will be cool enough to support mostly snow region wide. That’s when I think the best chance of accumulation is for most areas near and south of Boston. The precipitation will finally end Sunday night.
The bottom line here– we’ll have most light precipitation continuing off/on from late this afternoon right through Sunday night, so this is a fairly long duration event. However, most of this storm will be a mix of rain and wet snow around Boston and points south. That will make it hard to get much accumulation. Areas most favored for impactful snowfall will be north of the Mass Pike and outside of 128.
Snowfall: North of the Mass Pike and outside of 128, where wet snow will fall and accumulate gradually, expect 3-6″. Remember, wet snow has a harder time accumulating on roads, so I don’t expect travel to be exceptionally treacherous.
For much of the immediate Boston area, including the North and South Shores, I’m still expecting 1-3″. Again, the best chance for seeing that accumulation of wet snow will be Sunday evening as the storm winds down.
Mostly rain will fall south and east of Plymouth.
Winds: While it will be breezy along the coast Saturday night into Sunday morning gusts will only reach 30-40 MPH in most places. Almost a non-event for coastal areas.
Coastal Flooding: A 10′ high tide occurs at 10 AM Sunday, and with onshore winds a storm surge of about 1′ is likely. That will result in only pockets of minor coastal flooding.