Are ‘frozen’ atmospheric waves causing extreme weather?

Posted on February 26, 2013 by Bob Berwyn

Observational data confirms pattern changes

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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. (more…)

Filed under: Arctic, climate and weather, Environment, global warming | Tagged: , , , | 1 Comment »

Climate: The jet stream blues

Posted on January 21, 2013 by Bob Berwyn

Melting Arctic ice altering mid-latitude weather patterns

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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. (more…)

Filed under: Arctic, climate and weather, Colorado, global warming, Summit County snow and weather | Tagged: , , , , , , , , | 5 Comments »

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

Posted on June 8, 2012 by Bob Berwyn

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. (more…)

Filed under: climate and weather, Environment, global warming, seasons, Snow and weather | Tagged: , , , , , , | Leave a Comment »

Weatherblog: Some spring powder in Summit County?

Posted on May 10, 2011 by Bob Berwyn

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. (more…)

Filed under: avalanches, climate and weather, Colorado, La Niña, seasons, snow, Snow and weather, Summit County snow and weather, Weatherblog | Tagged: , , , , , , , , , , | Leave a Comment »

Weatherblog: What happened?

Posted on March 9, 2011 by Bob Berwyn

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.

SUMMIT COUNTY — Ouch!

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. (more…)

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Colorado: Spring weather outlook is on the dry side

Posted on February 25, 2011 by Bob Berwyn

La Niña weakens but influence should persist through March

Forecasters were on-target with their predictions for wet conditions in northwest Colorado during the early winter.

By Summit Voice

SUMMIT COUNTY — If the experts with NOAA’s Climate Prediction Center are right, this winter’s La Niña tap of moisture may slow to a trickle the next few months. The latest outlook, covering March through May, suggests there’s a 30 percent chance that most of Colorado will experience above average temperatures and below normal precipitation during the period.

The Climate Prediction Center’s outlook, along with other La Niña related information, was compiled into an informative package by Mike Baker, a National Weather Service meteorologist based in Boulder. Click here to see it.

One of the most interesting graphics show the temperature history for Nov. 1, 2010 to Jan. 31, 2011. Despite the perception of a cold winter, the statistics show that temperatures across nearly all of Colorado were well above average during that span. Summit County temperatures averaged about 2 degrees above average. The warmest average readings were along the Park and Gore ranges, the White River Plateau and the San Luis Valley. (more…)

Filed under: climate and weather, Colorado, La Niña, seasons, Snow and weather, Summit County Colorado, Summit County snow and weather, Weatherblog | Tagged: , , , , , , , | 2 Comments »

La Niña weakening, but effects will linger into spring

Posted on February 11, 2011 by Bob Berwyn

Neutral Pacific conditions forecast for summer

The Climate Prediction Center's spring outlook highlights above-average chances for dry conditions in the Southwest, including much of Colorado.

By Summit Voice

SUMMIT COUNTY — La Niña conditions, characterized by below-average sea surface temperatures across much of the equatorial Pacific, will persisted through January, but weakened slightly. Ocean temps warmed back to near normal in the easternmost reaches of the Pacific and an eastward shift of above-normal deep-water readings in the central Pacific, according to NOAA‘s Climate Prediction Center.

Nearly all the climate models forecast a weakening La Niña in the next few months, with a return to neutral conditions for the May – July period, with a few models showing a weak La Niña lasting through the summer, though forecasters have had trouble forecasting through what they call the “spring barrier.”

All in all, the Climate Prediction Center is forecasting La Niña influences to linger, including an enhanced chance of above average precipitation in the Northern Rockies and the western part of the Northern Plains, eastward through the Great Lakes region and the Ohio Valley. Chances are also better than equal for continued dry conditions across the southern tier of states. (more…)

Filed under: climate and weather, Colorado, El Niño, La Niña | Tagged: , , , , , , | 1 Comment »

Weatherblog: A bit of moisture, then a midweek warmup

Posted on October 18, 2010 by Bob Berwyn

A disorganized blob of moisture is headed into the Rockies, bringing a chance of showers through Monday night.

SUMMIT COUNTY — A large trough of low pressure moved ashore Sunday, spreading moisture into the Great Basin and bringing a chance of precipitation to the high country. A dusting of snow is possible over the higher peaks and ridges starting Sunday night and continuing into Monday, with an unsettled atmosphere aloft and moisture streaming in from the Southwest. Snow levels should drop Monday, with highs only forecast to reach the low 40s. Deep moisture is forecast over the area Monday night, which could boost snowfall as temperatures drop.

Overnight lows the next few nights are forecast to drop into the mid-20s, which should enable snowmakers to fire up their snow guns as they prepare for scheduled opening days in early November. Nighttime temperatures should stay seasonably cool through the week, but daytime highs will quickly rebound, climbing 4 to 8 degrees celsius Tuesday, and another 2 to 3 degrees celsius Wednesday, which means our highs could be back in the upper 50s by Wednesday afternoon, close to the seasonal average. (more…)

Filed under: Summit County Colorado, Summit County news, Summit County snow and weather | Tagged: , , , , , , | Leave a Comment »

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