A polar vortex blast of record cold air is headed to New England Thursday. Here’s what to know.
Thursday will begin relatively calm and somewhat quiet across most of New England. Greater Boston will see partly cloudy skies to start, but the clouds will quickly increase as the incoming front carrying cold air from the polar vortex approaches.
Your morning commute will be cold with temperatures in the 20s across the region with a slight breeze from the west, so you’ll want to bundle up. Highs will slowly, and briefly, reach the mid- to upper 30s across Greater Boston before the Arctic air arrives.
Highs on Thursday will range into the 30s across most of New England.Boston Globe
Blast of polar vortex air arrives
Temperatures will nosedive starting mid-afternoon as the Arctic front passes through, initially plummeting into the 20s and then dropping further into the teens. Wind gusts of 20 to 30 mph will make it feel even worse as we head into the evening.
Thursday night will be bitterly cold with temps below zero and in the single digits, setting up the coldest night of the season for all of New England, including Boston. Greater Boston may hold on to an overnight low of 10 to 12 degrees.
Temperatures will plummet to dangerously cold temperatures late Thursday and into Friday.Boston GlobeThursday night, wind chills across New England will drop to 20 degrees and lower.Boston Globe
What’s causing this rush of Arctic air?
The polar vortex is a tight band of wind that holds exceptionally frigid air high in the atmosphere in the stratosphere. It can occasionally cause atmospheric disruptions when a piece of the vortex splinters off, rushing pockets of bone-chilling Arctic air farther south. That’s what happened shortly after Thanksgiving and earlier this week as these vortex winds slowed substantially, allowing the polar vortex to stretch southward, dislodging pieces of bitterly cold air.
The good news is that this shot of brutally cold weather will only last for about 24 hours before temperatures improve slightly this weekend. The bad news? The Arctic air will return at the beginning of next week.
Scattered snow squalls possible
This front will also spur some scattered snow showers with the potential for a handful of snow squalls. Winter’s version of thunderstorms, squalls are sudden, short-lived bursts of moderate to heavy snow that can reduce visibility in a flash if you’re caught in one while driving, so make sure to keep your weather alerts on.
The snow squalls will likely occur while most of us are at work for the day, ramping up during the late morning and making a fast exit before the 5 p.m. commute home. Remember, these squalls will be very scattered, and like thunderstorms, will be hit-or-miss as the front progresses across the region.
Thursday will begin quietly until a front races through the region, sparking scattered snow squalls across New England.Boston Globe
Snow squalls are reflective of a very unstable winter atmosphere, where a front holding exceptionally cold air wedges relatively warmer air vertically into the atmosphere, condensing into a burst of snowfall.
Snow squalls are similar to summer thunderstorms, where a colder, dense air mass lifts the relatively warmer air vertically into the atmosphere, condensing into storms.Boston Globe
About an inch of snow is possible, with winds up to 30 mph. Take a look at how wind gusts increase throughout the day on Thursday.
Wind gusts will pick up to 20 to 30 miles per hour as the cold front passes through New England on Thursday.Boston Globe
How long will this cold spell last?
This Arctic cold air will persist into Friday. Friday morning will be dangerously cold, with wake-up temperatures around 11 degrees, and in the single digits west of Boston, so kids need to bundle up for the bus stop and workers for their commute in.
The good news is that this bitter cold won’t last. Dave has your weekend forecast ready to go, showing some temperatures likely rebounding. But, as I said, the nicer weather won’t last for long as another shot of cold air returns Monday into Tuesday.
Greater Boston: Cold and turning breezy. Partly cloudy to mostly cloudy skies. Spot snow shower or squall possible. Highs to the mid- and upper 30s. Very cold air arrives in the evening, dropping lows into the 10s. Clearing late.
Southeastern Mass.: Increasing clouds. Highs to mid and upper 30s. Turning breezy with a snow shower or squall chance. Temps drop Thursday night into the 10s. Clearing late.
Central/Western Mass.: Mostly cloudy with highs reaching low to mid-30s. Snow shower or squall chance during the day. Some clearing in the evening, but temperatures drop. Lows to the single digits, but even negatives are possible.
Cape and Islands: Blend of partly to mostly cloudy skies. Highs to the upper 30s and low 40s. Chance for a snow shower or squall. Lows to the upper teens. Clearing late.
Rhode Island: Blend of clouds and sun. Highs to the mid and upper 30s. Snow shower and squall chance. Breezy in the afternoon. Temps drop quickly into the teens at night.
New Hampshire: Mostly cloudy with highs to the upper 20s to mid-30s, from north to south. Snow showers and squall chance as early as late morning into the afternoon. Lows crash to the single digits and negatives under mostly clear skies.
Vermont/Maine: Mostly cloudy with highs to the upper 20s and low 30s across both states. Snow squall chance during the late morning in Vermont to the late afternoon in Maine. Breezy during that stretch. Lows to the single digits and negatives as skies clear up.
The forecast across Boston for the next seven days.Boston Globe
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Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.
