While most of Sunday is quiet across New England with sunshine fading behind clouds, we're carefully monitoring the progress of two separate systems back to the south and west.
One is a cold front moving through the Mid-West as of Sunday morning, and the other is a strengthening area of low pressure off the coast of the Southeastern United States. Both will have implications to our forecast beginning Sunday night.
As early as dinner time, the strong storm working up the east coast will trigger a few rain and snow showers over Cape Cod and the Islands.That's really just the fringe of the storm though. Most of the action will stay offshore.
But, as that storm blows up offshore, the disturbance from the Mid-West will be arriving in New England. The interplay between the two systems will likely result in what's known as a Norlun Trough, essentially an elongated area of low pressure where winds converge and precipitation is locally heavy.
Determining exactly where one of those troughs sets up is very tricky, and critical to the forecast. Remember, it often boasts a localized area of robust precipitation. In this case, some locally heavy snow.
It's most likely to impact towns somewhere the Maine/New Hampshire border, into coastal Massachusetts. That would include spots like Cape Ann, the outer portion of Cape Cod, and potentially even areas around Boston.
The bottom line is that with two systems approaching late Sunday, clouds will increase and snow showers will break out overnight. In most spots just a coating-2" will fall, but in coastal Massachusetts where heavier snow bands set up some localized amounts may approach 4". Not everyone will see totals that high, to be sure (which is what I mean by localized).
Fortunately many people are off on Monday for the holiday, meaning impacts to the commute from any fresh snow should be less meaningful than on a typical Monday.
Off and on snow showers will continue during the day on Monday as a cold northwest wind blows and sends temperatures dropping into the teens and 20s.