A front loader drives through a snowstorm along Union Road on Thursday, Nov. 20, 2014, in West Seneca, N.Y.
This week's snowstorm in Buffalo, New York, which has come in two deadly rounds that together have left many communities just south of the city struggling to cope with what will likely amount to a year's worth of snow in the timespan of less than one week, has been one of the most capricious and stubborn lake-effect events that meteorologists have witnessed in recent years.
Lake-effect snow events occur along the Great Lakes when cold Arctic air blows over relatively mild and open lake waters during the fall and spring. These snowstorms can tie forecasters in knots because they can suddenly intensify, shift course on a moment's notice, and deliver some of the world's highest snowfall rates. For example, on Thursday evening, the National Weather Service was warning that some towns south of Buffalo were seeing snowfall at greater than 4 inches per hour.
Improving lake-effect snow forecasts could save tens of millions of dollars and, given their impact on roadways, could also save lives. However, until recently, scientists didn't have the know-how to probe these storms with the fine-scale detail necessary to figure out exactly how they function, and what makes the difference between an ordinary lake-effect snow event and a wallop like the one this week.
The storm comes just as researchers begin sifting through the reams of data they gathered in a major scientific research project — the first of its kind to examine lake-effect snow — that brought more than 100 scientists into the path of lake-effect snowstorms during the winter of 2013-14. That campaign, known as Ontario Winter Lake-Effect Systems project, or OWLeS, is just starting to pay off in the form of new insights into how these storms work. The Buffalo event provides an interesting test case for these researchers, while serving as motivation to dig deeper.
Jim Steenburgh, a meteorology professor at the University of Utah, said the Buffalo storm's first round confirms some of what he and his colleagues observed in high-resolution last year. These storms can have a “structure that’s really incredible… a structure that you sometimes see with severe thunderstorms,” he told Mashable.
From Tuesday through Wednesday, the narrow band of heavy snow that targeted towns such as West Seneca, New York, on Tuesday night, was barely 15 miles wide but more than 100 miles long. In chilling photographs, it resembled a wall of snow more closely akin to a broiling dust storm than a snow squall.
Even by the fickle nature of lake-effect snowstorms, the first round that pounded towns to the south of downtown Buffalo was a truly bipolar beast.
If you were on one side of the snow wall, you got three inches to a foot of snow from round one, which ended on Wednesday morning. If you were on the other side, inside the band, then good luck, because you likely got the most snow you’ve ever seen in such a short period of time, more than 5 feet.
Heaviest snowfall rates in the world?
Using new research tools, scientists have come to realize that these small-scale storm systems are both unique to the U.S. in many ways, and are more complex than most people realize.
"These bands that come off of Lake Erie and Lake Ontario, they probably produce the most intense snowstorms of anywhere in the world," Steenburgh said. "They produce these firehoses of snow."
The only other area of the world where such prodigious amounts of lake-effect snow occur is in northern Japan, according to Steenburgh, on the western coast of Honshu and Hokkaido, where up to 500 inches of snow fall annually. In Japan, though, the snowfall trigger is repeated rounds of frigid winds from Asia blowing over the warmer waters of the Sea of Japan, making the U.S. is home to the fiercest, lake-effect snow.
Intense lake effect bands have very dynamic vertical structures. Examples from the UAH XPR last winter: pic.twitter.com/xDtKsTSzpd— UAH SWIRLL (@UAHSWIRLL) November 18, 2014
To meteorologists, the Buffalo snow event serves as extra motivation to unlock the mysteries of these incredibly intense but notoriously difficult-to-forecast extreme weather events. While the National Weather Service succeeded in warning of the likelihood of heavy lake-effect snow well in advance of the event onset on Tuesday, forecasters did not identify the near-southern suburbs as the most likely target for the heaviest snow, since pinpointing the axis of heaviest snow in advance tends to be extremely difficult.
In fact, meteorologists often “nowcast” their way through many lake-effect snow events, informing those in the path of the snowbands that it is moving their way or about to leave their area as it happens.
We know the triggers, but many mysteries remain
Last winter, the scientists from nine research universities used a bevy of high-tech tools in the modern meteorologist's arsenal, from radars mounted on trucks, known as “Doppler on Wheels” or DOW systems, to upward-looking radars called vertical profilers. In addition, a radar-equipped aircraft flew in and around intense snowbands, all in an effort to better understand what makes these unique weather systems tick.
Several of the scientists involved in the project, which was funded by the National Science Foundation, said the Buffalo events have been unique in some ways, while also sharing the characteristics of other lake-effect snow events.
The trip-wire for major lake-effect snow events is well-known. These events occur when blasts of frigid, Arctic air blows down the entire length of an open-water lake, setting up huge temperature contrasts between the relatively warm lake waters and the extremely cold air above it. On Tuesday into Wednesday, the wind was blowing from the west-southwest across the entire expanse of Lake Erie. This long fetch allowed the air to gather a tremendous amount of moisture off the lake.
The typical Lake Erie water temperature for this time of year is about 47 degrees Fahrenheit, yet waters near Buffalo were in the low 50s Fahrenheit when the Arctic cold front passed through on Monday.
“It’s a striking event because it’s happened at a time of year when the lake is still very warm but we managed to have some very cold air pass over the lake, and it’s the warm water underlying the cold air that fuels these storms,” said Justin Minder, a meteorology professor at the University at Albany.
The difference between the air and water temperatures were as large as 50 degrees Fahrenheit when most of the 6 feet of snow fell, thereby causing what the NWS referred to as “explosive instability” as the frigid, dry air fanned out across the lake, picked up moisture, rose and condensed into deep, turbulent masses of clouds that dumped snow at rates that would be considered impossible in most other parts of the world, with the possible exception of Japan.
Karen Kosiba, an atmospheric scientist at the Center for Severe Weather Research in Boulder, Colorado, who led the Doppler radar teams during the OWLeS project, said that while many of the larger-scale dynamics that govern lake-effect snow events are well-understood, other factors are not. For example, forecasters have an extremely difficult time predicting ahead of time where the heaviest snowbands will set up, or even how many heavy snowbands will form. Sometimes multiple, lighter bands of snow can form instead of one long-duration, extremely heavy firehose of snow.
Kosiba, who has used the DOW radars to decode many of the mysteries of tornado formation, has identified small circulations associated with some intense snowbands, which she calls “mesovortices” because they occur on such a small-scale. These vortices, she said, may lead to sudden fluctuations in snowfall intensity, and can play a role in causing waterspouts over the Great Lakes.
Other researchers have been examining how upwind lakes can help precondition the atmosphere, by warming and moistening the air as it rushes toward Lakes Erie and Ontario, upping the odds that heavier snow will result from a downwind lake.
Kosiba said the Buffalo snow this week resulted from a perfect combination of ingredients, from a historically cold airmass for this time of year to an intense upper-level low pressure system, which enhanced atmospheric instability.
David Kristovich, who worked with Kosiba on the OWLeS project, said the Buffalo storm was “not really that uncommon.” It was the persistence of the snowband, Kristovich said, that set it apart from other similar events.
“What’s a little bit unusual is that Lake Erie was still rather warm, hasn’t frozen yet, and the area that was hit is not one of the most common areas to get the heavy snow,” he said in an interview.
“We’ve seen storms like this before,” Kristovich added, “but it really hit a very high impact area where there are a lot of people affected.”
He pointed to the constant aim of the lake-effect firehose as a remarkable feature of this storm, which was not seen during the events he examined last winter.
“Lake-effect bands move so easily from just little waves in the atmosphere at higher altitudes that move through,” he said. “This one was remarkably steady.”
Even during the two months of the field campaign, with radars scanning the skies in unprecedented detail in and around lake-effect snowbands,
Kristovich said he and his colleagues were “often caught by surprise” at the sudden movement of the snow several miles in one direction or another. “We’re going to have a unique dataset that is going to help us understand these shifts a lot better,” he said.
“We collected an enormous amount of data…. we’ll be looking at the data for years to try to discern what story the data are trying to tell us,” he said.
For Minder, Buffalo's epic snow blitz in Buffalo shows the usefulness of lake-effect snow research. “It’s exciting for us that we just did this field project on events very much like this,” Minder said of the ongoing snowstorm. “You never like to see people in distress… but this kind of further puts the fire in us to work on our research.”
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