Ocean-effect flurries in eastern Massachusetts Tuesday morning were the product of an onshore wind gathering moisture as cold air flowed over relatively warm ocean water.
With a shifting wind, those flurries redeveloped over the New Hampshire seacoast and coastal Maine around midday.
Meanwhile, an approaching storm center from the west will fire up snow showers in the mountains of western New England Tuesday afternoon. This will expand into eastern New England by late evening, then filling in as snow with a period of rain mixed in for Southern New England overnight.
The biggest problem from this event for southern New England, including Boston, doesn’t come from the amount of snow, but rather from a snap back to snow with temperatures dipping below freezing. These below freezing temps come just in time for the Wednesday morning commute, leading to road icing and perhaps resulting in some delays.
Farther north, the mountains will see all snow, driving accumulations up over half a foot before snow tapers Wednesday morning. Although the sun will break through for almost all of New England for a while Wednesday, an arctic cold front arrives during the afternoon.
You can expect this cold will be sparking scattered afternoon and evening snow squalls that, akin to summer thunderstorms, may drop locally enough snow to make roads slick.
The passage of the arctic front opens the door to the much-talked-about cold air moving east from the Midwest, holding temperatures to the single digits and teens. Thursday will also be struck with wind chill values well below zero through most of the day.
Although the air will moderate fairly quickly in our exclusive First Alert 10-day forecast, it will take some time, with daytime highs in the 20s to near 30 Friday and Saturday, then 40 degrees of warmer starting Sunday into much of next week.