The bad news? For the second time in less than a week, New Englanders are going to get pummeled with heavy snow, high winds, and the possibility of coastal flooding.
The good news? It’ll be short—though not painless.
While it might seem particularly punishing for the East Coast to have two storms within the space of a week, meteorologists are shrugging it off. “This happens more than some people might think,” Ed Vallee, a meteorologist based in North Carolina who owns a consulting firm, Vallee WX, that advises weather-sensitive industries like snow removal, agriculture, and resorts.
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To Vallee, while back to back nor’easters are certainly a punch in the gut, it’s not really something that indicates a more sinister scientific force, like climate change. But the science of what created two back-to-back monster storms is still quirky.
For starters, East Coasters who were basking in balmy, 70-degree weather toward the end of February can blame the temporary respite for causing the perfect conditions for this pair of nor’easters. “We had a stratospheric warming event that drove the warm conditions and led to the formation of a negative North Atlantic Oscillation, or NAO,” Vallee told The Daily Beast.
The NAO is an index that measures pressure patterns in the north Atlantic ocean, specifically in the area between southeastern Canada and Greenland. “When negative NAOs develop, it creates a blocking high pressure system,” Vallee said. “That higher pressure in southeastern Canada near Greenland is what’s classified as a negative NAO.”
In a move that defies geographic logic, the NAO in the Atlantic actually affects weather systems that are moving westward from the Pacific Ocean. Disturbances in weather tend to snowball into blizzards and storms that lead to the Midwest’s famously cold, harsh winters, which Vallee said helps to propel warmth ahead of them, so that by the time they hit the East Coast—and combined with the fact that the systems hit another ocean—storms get milder.
That’s not what happens with a typical nor’easter, which turns this usual pattern on its head and actually leads to a more intense storm. “When you have these high pressure blocking systems, it prevents storms from cutting west in major cities, so they develop off the East Coast,” Vallee said. Basically, the high pressure system is able to combat the normal storm weakening pattern that happens when systems travel west to east, so that the East Coast feels the brunt of a storm without the usual easing that occurs.
Which makes nor’easters that much more dangerous compared to their Midwestern blizzard cousins. “The strength of the storm is worse, stronger than what it might have been had it traveled from the west,” Vallee said. “It’s also more intense because it’s able to feed off ocean and atmospheric dynamics occurring here.” And that makes a nor’easter’s howling winds, teeth-chattering winds, and snow dump that much more devastating.
So why do we still make a big deal about nor’easters if they’re a normal hiccup in meteorology? Vallee said the media doesn’t help, pushing talk of a storm’s effects further out than would have been possible prior to social media. “Compared to this bombogenesis talk, this is a run-of-the-mill type of storm,” Vallee said. In fact, he predicted that this week’s storm will be less destructive than last week’s storm, which moved considerably slower than this one, bringing prolonged precipitation and winds.
But Vallee said that it’s not quite the end of winter yet. “There is a chance, early next week, for another coastal storm to develop in the southeast [United States] and travel up the coast,” he said, cautioning that it’s still too early to tell if this storm will develop into a nor’easter. Spring might be about a couple weeks away, but winter isn’t leaving quite yet.
