Cold and dry air remains entrenched not only in New England but throughout the Eastern two-thirds of the nation Tuesday morning as a mammoth area of high pressure – a fair weather dome – is sprawled across the Eastern United States. Given the shear size of the fair weather cell, New England is assured several days of storm-free weather until the upcoming weekend. To be storm-free doesn’t mean absent of any change at all, however, with subtle features like periods of wispy clouds and more pronounced changes like warmer air. The subtle features come first: energetic disturbances aloft, starved of moisture but able to carry varying amounts of high and middle altitude clouds through the area. Dry air in the lowest several thousand feet of the atmosphere prohibits these clouds from producing any snow, though one exception to the rule is just offshore of Outer Cape Cod, where a north wind over the water picks up enough ocean moisture to produce some ocean-effect flurries, driven by the temperature difference between ocean water and cold air. Nonetheless, with the wind unlikely to blow onshore, these light snowflakes will stay offshore. Temperatures steadily moderate in the days ahead, rising into the 30s by day Wednesday and 40s by Thursday, bringing melting to most of New England by the end of the week, continuing into Friday. The next storm, developing on the west side of our dominant dome of high pressure, trudges east from the Rockies to the Ohio Valley late this week, and moves into New England Saturday. Though it’s early for details, the timing seems similar to our most recent weekend storm – arriving later Saturday and lasting into Sunday, though this one could linger a bit longer. The noteworthy difference between the two storms will be less cold air this time around, meaning a rain/snow line is likely to be involved and ride inland from the coast Saturday and Sunday. The storm should be gone by Monday, dropping plowable snow in at least Northern and Western New England with amounts to be determined in Southern New England, particularly near the coast, and next week looks storm-free through at least Thursday in our exclusive First Alert 10-day forecast.
A shot of winter air is not only cold but dry – meaning this Canadian air will make for plenty of Friday sunshine, but rather ineffective sunshine with temperatures not exceeding the 20s and wind chill values stuck around or under ten degrees for most of us. Of course, wind chill is driven not just by the cold, but by the wind – not forecast to be damaging, but gusting to 40 mph through the day Friday. Even as the wind starts to quiet Friday evening and night, it’ll still be breezy enough to hold wind chill values in the single digits and eventually, as the wind quiets more after midnight, the temperature will drop to pick up where the wind chill leaves off – in the single digits for many. A frigid Saturday morning sets the stage for our next storm to fall as predominantly snow, starting during the late afternoon to early evening, west to east, Saturday and continue through the evening and the first half of the overnight. A rain/snow line will likely move in from the southeast, but while this may impact the Cape and far Southern New England and the immediate coast of the South Shore, it’s unlikely we see that change farther north. Expect sunshine and clouds to mix Sunday with a busy westerly breeze, bumping temperatures into the 40s so driveways and walkways cleared Sunday morning will finish melting off. Melting slows appreciably for most of next week even though there’ll be sunshine – our exclusive First Alert 10-day forecast shows chilly air around most of next week until warming ahead of another possible storm next weekend.
New England stands on the precipice of a new, colder weather pattern, set to prevail throughout nearly all of our exclusive First Alert 10-day forecast. As we await the change of air, a storm system zipping by and delivering up to half a foot of snow to Northern New England with only a coating or mix of rain and snow to most of Southern New England will keep moving…but leaves enough moisture behind for renewed rain and snow showers in Eastern New England Thursday afternoon, and some snow showers in Western New England may fire again with atmospheric energy aloft. All of this may leave some moisture on the roads as a colder wind kicks up from the northwest, gusting as high as 50 mph at times Thursday overnight and sending temperatures plummeting to 20° by dawn south and single digits north with wind chill values near zero and below zero in Northern New England while turning some of that road moisture to ice. Friday brings sunshine, but the same dry Canadian air that clears the sky also is biting cold, with highs only in the 20s, teens north, and wind chill values never rising much above ten degrees. As the wind quiets Friday night, temperatures will tumble and that sets the stage for a cold day of increasing clouds Saturday ahead of the next approaching storm. Moving in from the west, Saturday’s storm induces a southerly wind, but any attempt for that warmth to move north is first met by a wall of cold air, and that clash of air first results in a swath of snow spreading across New England late in the day Saturday and lasting through the night Saturday night. Snow should be gone by Sunday with sun returning and the mild air associated with the storm center will allow for any driveways and walkways that have been cleared of snow to melt off nicely with highs in the 40s before cold air returns for a stay: highs in the 20s and 30s all of next week, but with dry enough air to hold snow at bay.