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Climate: Is the jet stream getting curvier?

A warming Arctic is changing the configuration of the jet stream, which affects mid-latitude weather. GRAPHIC COURTESY NOAA.

A warming Arctic is changing the configuration of the jet stream, which affects mid-latitude weather. GRAPHIC COURTESY NOAA.

New study traces historic changes in North American weather patterns

By Bob Berwyn

FRISCO — A new University of Utah-led study suggests that this past winter’s persistent weather pattern across North America is linked with changes in the jet stream that may become even more pronounced as the Earth’s climate warms.

“If this trend continues, it could contribute to more extreme winter weather events in North America, as experienced this year with warm conditions in California and Alaska and intrusion of cold Arctic air across the eastern USA,” said geochemist Gabe Bowen, senior author of the study. Continue reading

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Climate study links rainy European summers with dwindling Arctic sea ice

A NASA satellite image shows Arctic sea ice.

A NASA satellite image shows Arctic sea ice. Image courtesy NASA.

Changes in the Arctic likely to have widespread hemispheric impacts

By Summit Voice

FRISCO — A new climate study by scientists at the University of Exeter (UK) adds to the growing body of research looking at the hemispheric impacts of dwinding Arctic sea ice.

The findings suggest that that the loss of ice shifts the jet stream farther south, bringing increased summer rainfall to northwestern Europe, but drier conditions to the Mediterranean region. The study could offer an explanation for the extraordinary run of wet summers experienced by Britain and northwest Europe between 2007 and 2012.

In another recent study, scientists with the Cooperative Institute for Research in Environmental Science found that as sea ice disappeared, the areas of relatively warm open water began to strongly influence the atmosphere, increasing surface temperatures in the region, and shifting low- and high-pressure zones around most markedly in the fall and winter.

And a NOAA study found Arctic warming has shifted the normal west-to-east flowing upper-level winds to a more north-south undulating, or wave-like pattern. This new wind pattern transports warmer air into the Arctic and pushes Arctic air farther south, and may influence the likelihood of persistent weather conditions in the mid-latitudes. Continue reading

Op-ed: Did global warming cause Alaska heat wave?

asdf Image Credit: NASA/Jeff Schmaltz, LANCE MODIS Rapid Response Team, NASA GSFC

A NASA satellite captured this clear-sky image of Alaska on June 17, as parts of the state saw record-high temperatures. Photo courtesy NASA/Jeff Schmaltz, LANCE MODIS Rapid Response Team, NASA GSFC. Click here to learn more about this image at the NASA Earth Observatory home page.

Maybe not, but it’s part of a pattern of more frequent climate extremes

By Bob Berwyn

FRISCO — A recent heat wave in Alaska has triggered yet another pointless debate about whether the record-breaking temperatures at some weather stations is a sign of global warming.

One of the best examples of how many journalists are missing the point came in the usually sharp-edged Alaska Dispatch in a story titled Why Alaska’s heat wave is a bad example of global warming.

After reciting a list of temperature statistics, downplaying wildfires and making critiques of other blog posts, the author ends with this assertion: “Moderation, it would seem, is the key to accurately representing data and making an informed decision on climate change.”

It’s not even remotely clear what is meant by moderation, but the reference to data is even more puzzling, considering that every credible temperature record from the past 50 years shows an inexorable rise in global temperatures — that’s why it’s called GLOBAL warming, regardless of what year-to-year, or decade-to-decade cycles may have been observed in Alaska. Continue reading

Global warming link eyed in extreme June weather


June 2013 flooding in Passau, Germany. Photo courtesy Stefan Penninger via Flickr and the Creative Commons.

German researchers cite ‘frozen’ jet stream waves as possible sign of climate change

By Summit Voice

FRISCO — Ten days of weather that included the largest tornado ever measured and some of the worst flooding Europe has ever seen are sure to rekindle the heated debate about possible links between global warming and extreme weather.

And despite the countless statistical arguments suggesting there has been no overall increase in extreme weather events, some scientists are becoming more willing to make the link, including researchers with the Potsdam Institute for Climate Impact Research.

In an interview with a regional German newspaper, the director of the research group referenced recent research that suggests the jet stream may be slowing down, wavering farther north and south and, at times, getting “stuck.” During May, a series of cyclonic storms traveled along this frozen jet stream wave, bringing seemingly endless rain and widespread flooding, said Hans Joachim Schellnhuber. Continue reading

Study tracks links between sea ice and climate

No smoking gun — yet


Large areas of open water where there historically was ice is affecting regional air temperatures and atmospheric circulation in the Arctic. Image courtesy NASA.

By Bob Berwyn

FRISCO — There’s no doubt that the continuing decline of Arctic sea ice is going to affect climate and weather across the northern hemisphere, but researchers are still trying to pinpoint exactly what the impacts will be.

In one recent study, scientists with the Cooperative Institute for Research in Environmental Science found that as sea ice disappeared, the areas of relatively warm open water began to strongly influence the atmosphere, increasing surface temperatures in the region, and shifting low- and high-pressure zones around most markedly in the fall and winter.

“The way I see it, it’s one of the wild cards out there,” said Mark Serreze, director of the National Snow and Ice Data Center. “The issue is just what those changes are going to  look like. That’s what we’re really still grappling with, we don’t have a handle on this … Is there a smoking gun? No, not yet,” Serreze said, discussing the findings of the new study. Continue reading

Are ‘frozen’ atmospheric waves causing extreme weather?

Observational data confirms pattern changes


Heat building up over the Arctic is interfering with global circulation patterns, leading to more intense, frequent and extended extreme weather events. Diagram courtesy NOAA.

By Summit Voice

FRISCO — Increasing global temperatures are “freezing” atmospheric waves, resulting in more frequent weather extremes, including the 2011 U.S. heat wave and a 2010 heat wave in Russia that coincided with unprecedented flooding in Pakistan.

Scientists have surprised by how far outside past experience some of the recent extremes have been. The new data show that the emergence of extraordinary weather is not just a linear response to the mean warming trend.

“What we found is that during several recent extreme weather events these planetary waves almost freeze in their tracks for weeks,” said Vladimir Petoukhov, lead author of a study to be published this week in the US Proceedings of the National Academy of Sciences. “So instead of bringing in cool air after having brought warm air in before, the heat just stays. In fact, we observe a strong amplification of the usually weak, slowly moving component of these waves,” Petoukhov said. Continue reading

Climate: The jet stream blues

Melting Arctic ice altering mid-latitude weather patterns


A huge and persistent ridge of high pressure in the eastern Pacific has been shunting the jet stream northward, preventing storms from reaching Colorado. The pattern has been in place much of the winter, sustaining serious drought conditions across parts of the Southwest. Graphic courtesy San Francisco State University.

By Bob Berwyn

SUMMIT COUNTY — If it feels like the weather has been stuck in a rut, that may not be too far from the truth. The jet stream is slowing down and meandering farther north and south, with more blocking patterns setting up across the northern hemisphere.

That leads to more extreme weather, both on the wet and dry side of the scale, said Rutgers University research professor Dr. Jennifer Francis, speaking at last week’s Glen Gerberg Weather and Climate Summit in Breckenridge.

Francis has been studying the connection between vanishing Arctic sea ice and weather in the mid-latitudes of the northern hemisphere, and evidence is piling up that the intense warming at high latitudes has serious implications for North America, Europe and Asia. Continue reading

Global warming: Cornell researchers say melting Arctic ice may be setting the stage for more extreme winter weather

A weakening of the polar vortex and jet stream is likely to lead to more severe winter weather outbreaks.

‘Arctic wildcard stacking the deck in favor of more severe winter outbreaks

By Summit Voice

SUMMIT COUNTY — Evidence continues to mount that melting Arctic ice is having a significant effect in the mid-latitudes, where most people live, and it’s not something that’s going to take decades to develop.

Instead, researchers say, the warming of the high latitudes has decreased a historic pressure gradient at the boundary of the high- and mid latitudes. Basically, the pressure difference has decreased, and that is having a fundamental effect on the way the jet stream moves from west to east in the northern hemisphere. Continue reading

Weatherblog: Some spring powder in Summit County?

Wilderness Sports sponsors the Summit Voice weatherblog. Click to visit Wilderness Sports online.

Winter weather advisories posted for Tuesday night through late Wednesday

A spring sunset over Buffalo Mountain in Summit County, Colorado. BOB BERWYN PHOTO.

A big-picture view of the Pacific shows a big subtropical jet stream far to the south and some remnant winter energy swirling in the Gulf of Alaska. In between, an area of disturbed weather will move across the Rockies the next few days, bringing some fresh snow.

By Bob Berwyn

SUMMIT COUNTY — A classic spring storm is rolling across the West, marked by a deep trough of low pressure extending down into the desert Southwest. As an “inside slider,” the low will move east of the Continental Divide and set up a deep, moist northeast flow that could produce significant snowfall on the east slope of the Front Range under upslope conditions.

A winter weather advisory from 12 p.m. Tuesday night to 6 p.m. Wednesday (May 11), with 4 to 8 inches of snow possible above 7,000 feet along the Front Range. The winter weather advisory extends to the higher terrain of Summit County, where the National Weather forecast also calls for the chance of 4 to 8 inches of snow across the higher terrain. A-Basin could pick up some decent snow once the weather system moves east of the area Wednesday and the flow switches around to the north.

Farther west and south, around Vail, Aspen and Crested Butte, a winter storm warning is in effect, with heavier snow expected across south-facing slopes Tuesday night, shifting to north-facing slopes Wednesday. Continue reading

Weatherblog: What happened?

Wilderness Sports sponsors the Summit Voice weatherblog. Click to visit Wilderness Sports online.

A persistent Gulf of Alaska low pressure system may send some snow love our way the next few days in the form of some short wave impulses.


What sounded like it was going to be a promising Monday storm fizzled out with a few measly waves of snow over the Gore Range in the afternoon, followed by a starry night and few more flurries Tuesday morning, all adding up to just a couple of inches of snow in the Summit County mountains.

As late as 11 p.m. Monday night, the forecasts still included winter weather advisories, watches and warnings, while skies in Summit County were completely clear.

The big snows fell in the San Juans, as the storm weakened and split, with most of the energy heading south, then east into Oklahoma, Texas and Kansas, where they can use the moisture. Silverton Mountain reported a 28-inch storm total, and several other San Juan ski areas picked up well over a foot of snow. Continue reading


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