Today’s weather will be dominated by the Gulf of Maine and its addition of low-level moisture to developing east/southeast winds. As winds shift midday, the very cold airmass that has settled in across New England, Atlantic Canada, and the adjacent ocean will start slowly departing the region. On its way out though, it will pick up moisture and some instability from the Gulf of Maine and send it towards the coast.
The first noticeable impact of this process will be increased cloud cover developing midday, first near the coast then inland. Snow will then break out early in the afternoon along the NH Seacoast before sliding up into Maine late afternoon/early evening. The low-level moisture here is actually fairly deep, extending to around 5,000ft where the temperature is -10C. That means that we should be able to get ice crystal growth, though the setup will be marginal (snowflakes and ice crystals like to grow best at temperatures of -12 to -18C). Given that we’re sitting right on the edge of nucleation, I wouldn’t be surprised to see some periods of freezing drizzle where supercooled water droplets can’t grow into ice crystals but can freeze on contact with objects at the surface. Not much accretion is expected but it only takes a hundredth of an inch or so to make travel slick. So take it easy on the evening commute!
Farther north, mostly sunny skies will hang on for most of the day before low clouds sweep in. High temps will range from the high 10s up north to the high 20s in the south.