Cars make their way down Electric Road in southwest Roanoke County past Tanglewood Mall on Friday morning, Jan. 22, 2016, near Roanoke, Va.
What makes this blizzard to end all blizzards tick? The factors making it so formidable are also helping it to deliver upwards of two feet of snow on the nation's capital, where a big storm is usually defined in inches (not feet), yet nearly entirely miss southern New England, which has been a blizzard magnet in recent years...
Here's why this storm is such a beast...
Potent upper level energy
The spark for this storm is a piece of atmospheric energy at the mid and upper levels of the atmosphere, which spun its way toward the Gulf of Mexico on Thursday night, igniting a round of severe thunderstorms in Louisiana, Mississippi and other states.
This energy derives much of its power from a deep dip in the jet stream, which encourages air to rise at certain points along it.
Computer model projection showing the powerful upper level low digging into the Mid-Atlantic and Southeast on Jan. 23, 2016.
Image: Levi Cowan
This upper-level low will provide much-needed energy to a new surface area of low pressure just off the coast of the Carolinas by Friday night. But this upper-level system will align itself right on top of the coastal low, causing the storm to be captured by the upper level air flow, like a spinning figure skater balancing another on top of them.
The end result of this will be a storm that moves extremely slowly, pumping a moist flow of air westward, toward an area of colder, drier air, and creating ideal conditions for heavy snow and sleet.
The energy available to this storm system is likely to produce bands of extremely heavy snow, and quite possibly thundersnow from Virginia northeastward into parts of New Jersey on Friday night and Saturday.
Unusually mild Atlantic waters
The coastal storm will be what is known as a baroclinic storm system, meaning it derives its energy from temperature and moisture differences across relatively short distances. The presence of unusually mild ocean waters just off the East Coast — on the order of 5 to 6 degrees Fahrenheit above average for this time of year, along with the typically mild waters of the Gulf Stream Current, will help the storm strengthen.
Sea surface temperature anomalies off the East Coast on Jan. 22, 2016.
More importantly, it will help to pump unusually moisture-rich air to the west and northwest via a low-level jet stream, piling up blockbuster snow totals in Virginia, West Virginia and Washington, D.C., in particular.
Cold Canadian high-pressure area
To the north of the storm system there is a strong area of high pressure. The circulation around this high is injecting cold, dry air into the storm system, feeding it through what meteorologists know as a "cold conveyor belt." This ensures that the mild, moist air gets wrung out of the atmosphere in the form of snow, not rain.
But the high, along with an accomplice between northeast Canada and Greenland, is also serving as a block against northward movement by the storm.
In many cases, storms that form near Norfolk, Virginia, travel northeastward, up the Northeast coast, dumping snow from Washington to Boston. This storm, though, is going to get stuck for a while, before skedaddling off to the east-northeast, well south of Long Island.
This track, thanks in part to the position of the area of high pressure, will ensure a tight snowfall gradient on the northern side of the storm, with New York City possibly picking up 6 to 12 inches and Boston seeing little to no snow at all.
The pressure difference between the low-pressure area crawling along the Mid-Atlantic coast and the high-pressure area to the north will result in extremely strong winds directed at the New Jersey, Delaware and Maryland shoreline. This will also cause dangerous coastal flooding, though the flooding should remain below Hurricane Sandy levels, according to the National Weather Service.
Persistent low over Canadian Maritimes
A strong vortex is present across northeastern Canada, and over the frigid and stormy waters between Canada and Greenland. In recent days, this area of low pressure has actually sagged to the southwest, which in turn has turned upper level winds more northwesterly than westerly over Maine.
The animation below shows this persistent circulation quite clearly in the top right portion of the frame. The developing snowstorm is in the bottom portion of the frame.
The effect of this might seem subtle at first, but it may be helping to keep the storm further south than it otherwise would go, since it cannot plow headfirst into such strong headwinds.
Typically, classic nor'easters that strike southern New England as well as the Mid-Atlantic do so when the confluence zone, or area of strong west-to-northwesterly winds well north of the storm system, is located further to the north and west, across Quebec, compared to this setup.
El Niño, Global warming tilting the odds?
The mild waters also raise the question of whether global warming is contributing to such an unusually prodigious snowstorm. Similar questions came up last year, when a series of blizzards buried the Boston area under a cocoon of snow.
"Take unusually warm Atlantic ocean surface temperatures (temperatures are in the 70s off the coast of Virginia), add a cold Arctic outbreak (something we’ll continue to get even as global warming proceeds), mix them together and you get huge amounts of energy and moisture, and monster snowfalls, like we’re about to see here," said Michael Mann, a climate researcher who directs Penn State University's earth systems science center.
Mann said the ocean temperature anomalies of 5 to 6 degrees Fahrenheit above average would yield more than a 20% increase of the moisture content of the air overlying that layer of ocean waters. That air, in turn, "is getting entrained into the system to produce the heavy snowfalls," he said in an email to Mashable.
Mann said it isn't clear how big of a role climate change might be playing, though, compared to other factors.
Studies have shown that heavy precipitation events — both rain and snow — have been increasing in frequency and severity in the Northeast region in the past few decades. These trends have been linked to manmade global warming on top of natural climate variability.
Kevin Trenberth, a senior researcher at the National Center for Atmospheric Research in Boulder, Colorado, told Mashable that the larger than normal contrast between the cold continent and mild ocean waters is adding fuel to storms like this one.
Surface low pressure map along with precipitable water normalized anomalies for Jan. 23, 2016, showing a corridor of moist air flowing around the East Coast blizzard.
"In winter it is cold over the continent. But it is warm over the oceans and the contrast between the cold continent and the warm Gulf Stream and surrounding waters is increasing," he wrote in an email. "At present, sea-surface temperatures are more the 3-degrees Fahrenheit above normal over huge expanses (1,000 miles) off the Northeast coast and water vapor in the atmosphere is perhaps 15% higher as a result. Up to half of this can be attributed to climate change."
He also said the ongoing strong El Niño event in the Pacific Ocean may have influenced the storm track of this storm as well as the extra heat present in the Atlantic, since the Atlantic tends to have less active hurricane seasons and winter storm seasons during El Niños, allowing warm water anomalies to persist.
"So when the right storm does come along, conditions are very favorable for it to have a big impact," he said.
Interestingly, this storm will help to cool off those waters, in part by churning cooler water up from the depths as well as evaporating moisture.
Ryan Maue, a meteorologist with the private weather firm WeatherBell Analytics, said on Twitter that the process of forming a rapidly intensifying coastal storm involves much more than just higher-than-average sea-surface temperatures.
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