Winter weather weirdness may be just beginning

Brace yourself. November’s white nightmare could become a recurring bad dream of varying intensity.

While last week’s winter blast appears to be the freak offspring of a typhoon-blasted jet stream and a warm Lake Erie, it’s also part of a long-term pattern that shows no sign of changing.

Meteorologists and geographers say that lake-effect snows have increased as temperatures have warmed in recent decades. That means more bizarre early-season storms, though not necessarily as bad as last week’s, are likely in the future as the warming trend continues.

“The general notion is that, as the climate warms and the lakes hold their warmth longer into the fall, you’re going to see a lot more lake-effect snow until it’s too warm to have much snow,” said Mark Monmonier, distinguished professor of geography at Syracuse University and the author of the 2012 book “Lake Effect: Tales of Large Lakes, Arctic Winds, and Recurrent Snows.”

Keep your shovels handy, though, because that breaking point – when lake-effect snow is replaced by lake-effect rain – likely won’t come until mid-century, the New York State Energy Research and Development Authority said in its updated report on climate change in the state earlier this year.

For the next few decades, then, conditions will be increasingly ripe for the creation of winter white-outs, although meteorologists said most won’t be as bad as the one that buried South Buffalo and the Southtowns with snow piles that in some places were taller (or deeper) than many teen-age boys.

That doesn’t mean you can attribute last week’s storm to climate change. Meteorologists say that individual weather events just can’t be explained as the byproduct of a historical trend. Instead, each is the product of a recipe that nature seems to just throw together without regard for how it will turn out.

This month, sadly, the recipe appears to be: Create one super typhoon near Asia. Use super typhoon’s remnants to push the jet stream out of whack so it sends arctic air down across most of the United States – and directly across the relatively warm waters of Lake Erie.

Results: Lake-effect snow totals of between 3 and 7½ feet south of Buffalo.

The main ingredient – or culprit – appears to be Super Typhoon Nuri, which formed in the Philippines early this month before tracking northward to the Bering Sea.

There, Nuri “caused a ripple effect on the jet stream,” meteorologist Jeff Masters of the Weather Underground blog wrote last week. And as a result, strange things started happening very far away.

As Nuri moved north, it pushed arctic air south – way south. In Big Bend National Park on the Texas-Mexico border, nighttime temperatures plunged into the low 20s at mid-month. Temperatures in Charlotte, N.C., dropped into the teens. And last week, that rejiggered jet stream blew cold arctic air straight across the comparatively warm waters of Lake Erie – the classic combination for producing lake-effect snow, and lots of it, in Buffalo and points south.

Adding it all up, the National Aeronautics and Space Administration – which watched it all happening on its weather satellites – said on its website: “While the Bering Sea Superstorm did not directly cause the snow event in New York, it did set the stage for it by nudging the jet stream into an unusual shape that sent a pulse of cool Arctic air south over the central United States.”

‘Unusual’ is normal

The trouble is, the jet stream’s “unusual shape” isn’t all that unusual anymore – and that’s just one reason why big early-season lake-effect snows may become our new normal.

“We’ve seen an unusual number of extreme jet-stream patterns like this in the past fifteen years, which happens to coincide with the period of time we’ve been observing record loss of summertime Arctic sea ice and record retreat of springtime snow cover in the Arctic,” Masters, the weather blogger, wrote last week. “Could it be that these changes in the Arctic are causing the wacky jet-stream behavior of recent years? That’s the theory being advanced by a number of prominent climate scientists.”

The jet stream is driven by the temperature difference from the equator to the north pole, said David M. Wright, a graduate student at the University of Michigan who has studied lake-effect snow and the reasons behind it.

That temperature difference is narrowing as the planet warms, which means there is less energy available to change the course of the jet stream, Wright said. So when some extreme event like Nuri pushes the jet stream out of whack, it remains out of whack for what can seem like forever.

“This then allows for cold air (like what’s over the eastern United States) or warm air (like what’s over the western United States) to sit there for longer periods of time,” said Wright, the lead author of an American Meteorological Society Journal article called “Sensitivity of Lake-Effect Snowfall to Lake Ice Cover and Temperature in the Great Lakes Region.”

Those longer cold snaps are bad news for Buffalo, which sits at the eastern end of a warm – and warming – Lake Erie.

While Lake Erie was a degree colder than usual last week, according to the National Weather Service, it was still warm enough to produce tons of snow when it met the cold arctic winds being pushed across the lake surface by the jet stream.

How it happened

Eric Holthaus, a meteorologist who writes for Slate, explained how it happened.

“Truly extreme lake-effect snows gather their energy from a wide temperature differential between the lake temperature and the air temperature,” he wrote last week. “That temperature contrast produces atmospheric instability – the warm air immediately over the lake wants to surge upward through the colder air on top, bringing with it heaps of evaporated moisture. That moisture is quickly converted to snowfall in massive quantities, and deposited squarely on the hills and towns at the far end of the lake.”

Holthaus is among the many meteorologists who believe that climate change is leading to more lake-effect snow – not just because of the changes in the jet stream, but also because the lakes are getting warmer.

For proof, just look at the ice pack, or lack thereof: New York State, in its recent climate report, noted that annual ice cover has decreased 71 percent on the Great Lakes since 1973.

“And if you extend the season when Lake Erie remains unfrozen, you’re going to get more snow,” Holthaus said, while acknowledging that it “seems so weird” to think that a warmer lake could produce worse winters in the region.

The trouble is, that already seems to be happening. Scientists are not much for anecdotal evidence like last week’s storm or the 2006 “October Surprise.” Instead, they point to data proving that lake-effect snow has been increasing as the climate, and the lakes, have grown warmer.

More lake-effect snow

While showing wide year-by-year variations, a 2009 study in the Journal of Great Lakes Research, for example, showed the average annual lake-effect snow totals off of Lake Erie increasing by nearly 20 inches between 1925 and 2007.

Will that trend continue?

Many scientists think so. What’s more, they think early-season snowfalls like last week’s are increasingly likely just because that’s when the temperature differential between the lake and the upper atmosphere is at its greatest.

“The hypothesis is that as temperatures warm, the lakes are warming, and that sets up the possibility for cold air coming over warmer and warmer lakes,” said Adam Burnett, chair of the Department of Geography at Colgate University and the lead author of a 2003 paper making the connection between climate change and the increasing levels of lake-effect snow. “That will lead to increased lake-effect snow, although it may only be in the short term until temperatures get too warm for snow.”

For that short term, though, Buffalo area residents may want to heed Holthaus’ advice.

“If Slate suddenly transferred me to the Buffalo bureau,” he wrote last week, “I’d be investing in a snowblower.”

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