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| From Science 2.0. This general jet stream pattern has kept the West Coast warm and the eastern United States cold more often than not for the past two years. |
The answer of course is yes, but in the short term anyway, the cold and the snow is only grudgingly starting to relax. The long slog toward spring looks like it's going to be a slow one this year.
You also hear people asking if this long stretch of storms and frigid air with practically no breaks is unusual and the answer is and emphatic, "Very."
Big snowstorms and temperatures way below zero are routine in a New England February, but such weather is usually interrupted by spells of relatively mild weather and sunshine.
The jet stream, that strong river of fast flowing air high above us that controls the path of storms, usually wiggles and shifts and changes frequently, so the weather changes.
A storm blows through, the jet stream changes and sends a big blast of cold air south from Canada. The jet stream changes again, and you get a thaw.
Rinse, repeat.
STUCK JET STREAM
Lately, as you might have heard, the jet stream has been "stuck." There's a big northward bulge in the jet stream that has people in western North America wondering whatever happened to winter. In Vancouver, British Columbia, cherry blossoms are now blooming, more than a month and a half early.
This same jet stream has sent one Arctic air mass from the North Pole after another into the northeastern United States. That big northward bulge in the West is counterbalanced by a big dip in the jet stream to the east, which opens the door for those cold waves to plunge southward.
The jet stream then turns north again just off the New England, allowing storms to form in part by picking up moisture from the warm Gulf Stream, letting it interact with the cold air from Canada, and you get snowstorms.
The stuck pattern lets storms form in rapid fire fashion, basically with each shot of cold air from Canada, or almost every other day.
"It's like reloading a gun. It just shoots one after another at us," Alan Dunham, a National Weather Service meteorologist in Taunton, Massachusetts told New Bedford, Massachusetts-based South Coast Today.
Again, this configuration of the jet stream happens almost every winter. But it doesn't normally get stuck in one orientation for five weeks without a break.
In fact, this general jet stream pattern has more or less been intact since at least late 2013, and occasionally before that. Sure, it has broken down occasionally, sometimes allowing wet and cool weather in the West and warm and dry in the East. But it seems like it quickly reverts back to this "stuck" pattern.
That's why California has had such a terrible drought for four years now. The northward bulge in the jet stream, dubbed the "Ridiculously Resilient Ridge" has steered rainstorms away from the West Coast and caused lots of heat. Last year was the warmest on record in California. Dry weather and high temperatures equals drought.
On the flip side, the big dip in the jet stream, named by some the Terribly Tenacious Trough, has more or less held in place for a year and a half now. (With those occasional, aforementioned breaks)
That's why the so-called Polar Vortex cold wave last winter was so intense. It's also why the Midwest had a rather cool summer last year. It's also why a stripe from about Illinois to Louisiana had one of its top 10 coolest years in 2014, when overall for the globe, 2014 was the warmest on record
This jet stream stickiness is why winter has been so extreme in the Northeast so far this year.
WHY IS THE JET STREAM SO STUCK?
The snows of New England had in some sense their origins way out in the Pacific Ocean
As always with weather and climate, the answer is complicated. Nobody is really 100 percent sure. It probably has to do with a mix of things, ranging from natural cycles in the Pacific, air pollution in Asia, and of course, the biggest villain of all, human-induced climate change.
If there's a lot of storminess in the eastern and central Pacific, that tends to help build up the western ridge and eastern United States trough.
According to Mashable, something called the Madden-Julian Oscillation heated the atmosphere and changed upper altitude winds in the the northern Pacific Ocean, said Michael Ventrice of WSI Corporation in Andover, Massachusetts.
A typhone named Higos also formed in early February in the eastern Pacific, and it might have been the strongest one on record for so early in the season.
That helped really bolster the jet stream pattern that has brought so much winter misery to New England, says Mashable:
"The ripple effects were like setting a Slinky on a march down a staircase - downstream waves formed troughs and ridges that contorted the jet stream that encouraged air to venture south from the Arctic."
OK, but why all the storminess in the Pacific to set this jet stream weirdness in motion?
POLLUTION PROBLEMS?
Let's blame China!
Actually, there's potentially some science to back up my wild accusation against China.
A recent article by James West in Mother Jones says heavy pollution coming from the factories of China, that soot that keeps causing dangerous air pollution in Beijing, might be contributing to the rough weather we've had this winter.
Says Mother Jones:
"Over the past few years, a team at NASA's Jet Propulsion Laboratory and the California Institute of Technology has found that aerosols - or airborne particles - emitted from the cities fueling Asia's booming economies are making storm activity stronger in the Northwest Pacific Ocean. These storms wreak havoc on the polar jet stream, a major driver of North America's weather. The result: U.S. winters with heavier snowfall and more intense cold periods.
Pollution billowing from Asia's big cities, they found, is essentially 'seeding' the clouds with sulfur, carbon grit and metals. This leads to thicker, taller and more energetic clouds, with heavier precipitation. These so called 'extratropical' cyclones in the Northwest Pacific have become 10 percent stronger over the past 30 years, the scientists say."
We know the pollution in China is killing people there. Maybe the fatalities in this winter's disasters in the United States could indirectly lead back to China, too.
OF COURSE, GLOBAL WARMING IS SUSPECTED, TOO
It turns out global warming might cause at temporary areas of cooling in some regions, too.
Writing in Science 2.0, Jennifer Francis, a Research Professor in the Institute of Marine and Coastal Sciences at Rutgers University, said there is evidence that global warming is messing around with the jet stream, which in turn might help explain the kind of stuck weather patterns that victimized New England this winter.
She writes:
"Our own new work, published last month in Environmental Research Letters, uses a variety of metrics to show that the jet stream is becoming wavier and that rapid Arctic warming is playing a role. If these results are confirmed, then we'll see our weather patterns become more persistent."
In other words, stuck weather patterns might become the new normal.
Of course that's bad, because if the same weather keeps hitting the same area for weeks, you get disasters like the New England snows, the California drought, or other huge droughts, floods, heat waves or cold waves.
Despite the eastern United States cold, waters in the Atlantic Ocean a few hundred miles off the New England coast were unusually warm this winter. Storms gain energy, and tend to produce more precipitation when they feed off warmer waters.
Some of the nor'easters this winter did just that. When all that moisture lifted off the warm Atlantic Ocean was flung into the cold air over New England, that wetness fell as snow. Lots of it.
Writing in the Boston Herald, Weather Channel Meteorologist and Storm Chaser Jim Cantore said that warm water way off the coast should take at least some of the blame for the unprecedented New England snow blitz this winter.
This next bit will be cold comfort (ha!) to people in New England, but despite what happened this winter, the amount of cold air circulating around the North Pole has shrunk to record and near record lows in recent years.
According to the Washington Post's Capital Weather Gang:
"In what may see like a paradox, the amount of wintertime cold air circulating around the Northern Hemisphere is shrinking to record low levels. This winter (2014-2015, is on track to see the most depleted cold air supply ever measured."
Yeah, and too bad it seems like most of that depleted cold air supply has been sitting right over my house in Vermont for the past month.
THE NEXT FEW DAYS, WEEKS
The stuck weather pattern continues, but it is finally shifting around a little bit. It's not going away just yet, but New England might not be quite so extreme in the next few weeks.
The whole Ridiculously Resilient Ridge and Terribly Tenacious Trough arrangement is all shifting a little to the west this week.
That means the core of the cold waves is now plunging into the middle of the country, going all the way to near the Gulf Coast. That's what's setting off a series of snowstorms across the South in the past ten days or so.
The slight westward shift in the pattern means the Northeast will stay cold and stormy, but not as cold. And the storms might include rain, not just snow.
On top of that, there are some uncertain signs that heading into mid-March, the Ridiculously Resilient Ridge and the Terribly Tenacious Trough might weaken somewhat, at least temporarily.
If that happens, temperatures across the country might not end up as extremely cold in the East or extremely hot in the West.
But to all those people in New England stuck with the winter weather, keep those snow shovels and warm winter coats handy for the next few weeks at least. You're going to need them.
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