Frack Check WV » jet stream

OMG It’s Cold — The Polar Vortex and the Jet Stream

Duane Nichols — Fri, 05 Jan 2018 09:05:58 +0000

Amazing view of polar vortex & jet stream storm

The Polar Vortex, Winter Storm Grayson, and Climate Change: What’s the Connection?

From an Article by Brenda Ekwurzel, Union of Concerned Scientists, January 4, 2018

Forecasters are trotting out “polar vortex” and atypical terms like “Nor’easter bomb” and “bombogenesis.” These words signal the unusual and dangerous conditions forecast for winter storm Grayson and their implications for the southeast US, mid-Atlantic, and eventually New England and beyond. What do they mean?

Meteorologists use the phrase bombogenesis to describe a sudden and extreme drop in barometric pressure of at least 24 millibars over 24 hours, which leads to rapid intensification of a mid-latitude cyclone. We are used to hearing about North Atlantic cyclones during summer and fall—its the meteorological term for hurricanes—and now winter storm Grayson is drawing moisture from a similar cyclonic circulation that will bring blizzard conditions as it moves northeast just offshore of the US east coast.

Winter weather and global warming

With cold temperatures and icy conditions leaving the continental US reeling over the New Year, it might seem counter-intuitive to say that we’re still experiencing global warming. But as my colleague Peter Frumhoff puts it, saying that climate change isn’t occurring because of the cold in the eastern US is “like saying if everyone around me is wealthy then poverty is not a problem…local weather is not an indicator of changes in climate.”

Global warming is exactly that: global. The total area of the US, including Alaska and Hawaii, is only about 2 percent of the surface area of Earth. This map from the University of Maine Climate Change Institute showing the deviations from average temperature for this time of year demonstrates this concept well—much of the continental US may be unusually cold right now but most of the rest of the world is well above average.

Much of the continental US may be unusually cold right now but most of the rest of the world is well above average.

Alaska has been unusually warm this winter even though it is in the Arctic. It might seem strange that local weather events such as a balmy Alaska and freezing Florida can occur at the same time, but they’re examples of another phenomenon we can expect from a changing climate: more events at the extremes. Many scientists are studying these clues to explore the connections between a rapidly warming Arctic from climate change and shifting extreme weather patterns in northern hemispheremid-latitudes (i.e. the continental US and Eurasia).

Arctic cold outbursts reach the southern US

Scientists noticed an unusual winter pattern in the jet stream that started around the year 2000. Before that time the jet stream was typically fast with small waves that kept the cold air contained in the Arctic region. However, the jet stream began slowing down, and its waves meandering more.

The distance between the peak (like the green and yellow band peaking near the intersection of the borders between Alaska and the Yukon Territory of Canada in Figure) and the trough (the highlighted red, yellow, and green area near the southern US) has become much longer since the 2000s when compared to prior decades.

Scientific process and progress in understanding extreme weather

Scientists are making progress in better understanding how much natural seasonal patterns, ocean cycles, and other factors play a role in altering the jet stream and how much global warming is responsible. Some say a lot, others not as much. This is a robust scientific discussion that has continued to evolve over the past several years.

One thing is certain: no climate scientists say there is zero contribution from global warming. We agree on 90 percent of the facts of the issue—now we’re debating the remaining 10 percent.

How will we know when this particular scientific debate is over? One way or another, the scientific community will reach consensus—just as it has with climate change more broadly.

Assessments will shift toward keeping track of the changing percentage of contribution from climate change to the altered jet stream. And we’ll really know consensus is reached when this research is incorporated into longer-term outlooks for winter forecasts. In fact, a recent publication suggests that if the Arctic indicators—such as the strength or weakness of the polar vortex—were better incorporated into current winter forecasts, we could have two- to six-week previews of the winter temperatures in the northern hemisphere just like we get our 10-day forecast today.

If predictions become reliable enough, this could help cities and counties plan to distribute snow removal equipment to regions that will need it well in advance of storms. This knowledge may better protect people facing risks to their daily lives from the consequences of extreme cold winter storm events.

Does the Polar Vortex Mean ‘So Much for Global Warming’?

Duane Nichols — Fri, 31 Jan 2014 02:46:14 +0000

Note Unusual Weather Pattern

The Misbehaving Jet Stream has Upset Weather in the East (colder) and West (dry & hot)!

From an Article by Michael Mann, EcoWatch.com, January 30, 2014

Over the past couple of months, the some of the U.S. has seen the return of something many believed had been lost for good: cold weather. Although the current temperatures in the eastern U.S. may seem unusually cold, in the context of our history they really aren’t.

In fact, most of the cold that has made the news lately hasn’t been all that chilly compared what was “normal” for the 20th century. The bottom line? Because the last decade was the hottest on record (and just a year ago, the U.S. saw its warmest year ever) Americans have grown accustomed to warmer winters that make normal cold feel extreme.

Some then wonder why this winter has been so (normally) cold and why temperatures in Peoria this winter have not been warmed by climate change to, say, a balmy 60 degrees F?

Well, the short answer is that cold winters still happen even in a warmed world, but that doesn’t mean it’s cold everywhere. Alaska, usually snowy and frigid, has had two weeks of record high temperatures. Amazingly, the second half of January has averaged 40 degrees F above normal during some days in the central and western parts of the state.

The persistently jagged jet stream we have witnessed in recent weeks has led most recently to a “Drunken Arctic.” Stumbling south with polar winds and snow, this unexpected meteorological event has our collective attention. It is an unusual enough, if not unprecedented, event.

So, is there a climate connection to this strange occurrence? While more study is certainly needed, I have been increasingly impressed by the growing body of evidence that climate change may lead to more persistent meanders in the jet stream. In a world without global warming, the temperature difference between the freezing Arctic and warmer lower latitudes creates a pressure field that confines the jet stream to a relatively tight band around the Arctic, with wave-like meanders characterized by ephemeral “ridges” and “troughs.”

As the Arctic melts and warms, however, that temperature difference is reduced, and the meanders of the jet stream potentially become more pronounced and more sluggish. The more sluggish and persistent those meanders, the more persistent the patterns of regional warmth where the jet stream pulls warm air northward, and the regional cold where it pulls arctic air south.

Looking at this image of temperature deviations we can see how the Arctic, in its “drunken” meandering, has fallen head over heels, hitting the southeastern U.S. like an over-enthusiastic reveler face-planting in the gutter shortly after closing time. The large purple region over the eastern U.S. represents weather 20 degrees F colder than the 1979-2000 average. Compare that to the massive red expanse over Alaska and Canada, which indicates weather 20 degrees F warmer than the same baseline.

Perfectly encapsulating the upside-down, hung-over Arctic is this remarkable observation, courtesy of Jeff Masters of the popular Weather Underground blog: At 10 p.m. on Jan. 26 the temperature in Homer, Alaska (54 degrees F) was warmer than any other place in the contiguous U.S. except southern Florida and southern California.

As we approach Groundhog Day, celebrated in the iconic nearby town of Punxsutawney, the question we’re all asking here in central Pennsylvania of whether or not we’ll see an extended winter may in fact depend on what is happening instead thousands of miles to the north in the melting Arctic.

And the very same jet stream configuration responsible for the southward plunging Arctic air mass that chilling the eastern U.S. is associated further to the west with a “ridge” of high pressure that is pushing the warm, moist subtropical Pacific air masses that would normally deliver plentiful rainfall (and snowpack) to California well to the north.

Climate scientists were beginning to suspect a decade ago that the dramatic loss of Arctic sea ice might alter the jet stream in precisely this way, favoring conditions eerily like what we are seeing right now in California: unprecedented and devastating drought.

So to conclude, I propose a toast to the Arctic, whose instability should serve as a wake-up call to those steeped in denial. When it comes to kicking our “fossil fuel addiction” (as former president George W. Bush referred to it), let’s hope we’re not much further from hitting rock bottom. Because when a drunken Arctic leaves Alaska warmer than Georgia in mid-winter, and California as high and dry as it has ever been, we should know we (may) have a problem.

Also visit EcoWatch’s CLIMATE CHANGE page.

More Abnormal Winter Weather is Likely for US

Duane Nichols — Sat, 08 Dec 2012 19:12:28 +0000

: Scientific American: Climate & Weather

“The Winters of Our Discontent”

By Charles H. Greene, Director of the Ocean Resources and Ecosystems Program, Cornell University.

The full article was published in Scientific American, Volume 307, December 2012, pages 50 thru 55 and online on November 13, 2012.

Loss of Arctic sea ice is stacking the deck in favor of harsh winter weather in the United State and in Europe.

The past three winters in parts of North America and Europe were unusual. First, during the winters of 2009 thru 2011, the eastern seaboard of the US and western and northern Europe endured a series of exceptionally cold and snowy storms – including the February 2010 “snowmageddon” storm in Washington, DC, that shut down the federal government for nearly a week.

The winter of 2011 – 2012 brought even more surprises. The eastern US had one of its mildest winters on record, while other parts of North America and Europe were less fortunate. In Alaska, the average January temperature was a full 18 Fahrenheit degrees colder than the long term average. Europe saw extreme frigid temperatures and snowdrifts that were roof high. By mid-February, more than 550 deaths were due to these conditions.

How can we explain these outbreaks of severe weather during the past decade that was the warmest in the 160 years where instruments have tracked the global average temperatures: it appears to be caused by the record-breaking losses of summer sea ice in the Arctic Ocean.

Global warming has increased the loss of summer sea ice in the Arctic, which has altered atmospheric conditions that influence winter weather in the U.S. and Europe.
A weakened Jet Stream exhibits larger waves in its pathway, which can get stalled in place, locking an affected region such as the northeastern U.S. in a prolonged deep freeze.
The changes lead to invasions of Arctic air into the middle latitudes, increasing the likelihood of severe winter outbreaks, which occurred in the eastern U.S. and northern Europe in 2010 and 2011 and in eastern Europe in January 2012.
The deck may be stacked for harsh outbreaks during the 2012–2013 winter in North America and Europe.

Note: The Winter of Our Discontent, published in 1961, is John Steinbeck’s last novel. The title is a reference to the first two lines of William Shakespeare‘s Richard III: “Now is the winter of our discontent / Made glorious summer by this sun [or son] of York,…”