Global warming may drive more active La Niña pattern

Broad tree-ring record provides accurate ENSO history

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Researchers say tree ring records show that El Niño activity during the 20th century has largely been outside the range of natural variability.

By Summit Voice

Climate scientists have long suspected that global warming has an influence on the Pacific Ocean El Niño- La Niña cycle (El Niño-Southern Oscillation), but instrumental records tracking the shift between above- and below average sea surface temperatures don’t go back far enough to provide context for any recent changes in the pattern.

But scientists working at the International Pacific Research Center, University of Hawaii at Manoa say a new tree ring record extending back about 700 years has helped decipher long-term trends. The tree ring samples from both the tropics and mid-latitudes in both hemispheres support the idea that the unusually high ENSO activity in the late 20th century is a footprint of global warming said Jinbao Li, lead author of the study published online in the journal Nature Climate Change. Continue reading

New study helps pinpoint El Niño impacts

Findings could help improve long-range winter forecasts

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Shifting cycles of warmer and cooler water in the central Pacific influence weather patterns around the world.

By Summit Voice

FRISCO — A new study that sorts El Niño events into two categories could help forecasters develop better long-range forecasts to predict how the periodic warming of equatorial East Pacific waters may affect winter weather.

Part of the data for the research came from an array of buoys across the Pacific called the TAO-Triton array. The buoys observes conditions in the upper ocean to forecast El Niño months in advance, and for monitoring it as it grows and decays.

After analyzing all El Niño events since 1979, the NOAA and University of Washington scientists said the El Niños that show a drop in outgoing long-wave radiation from the tops of deep convective clouds are the ones that tend to play havoc with winter weathers. Continue reading

Colorado: A warmup, but no snow in sight

Drought expected to persist; water supply outlook grim

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Colorado’s snowpack hasn’t been above average since the big winter of 2010-2011.

By Bob Berwyn

FRISCO — Temperatures will begin to moderate across the Colorado high country the next few days, with highs climbing back to near seasonal norms, which is only in the lower 30s, but that should feel downright balmy after enduring an Arctic air mass the past few days.

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Dry conditions persisted across Colorado in the autumn of 2012, especially in the plains.

The nicest weather will be up on the mountain slopes, because warmer air aloft will trap cold air on the valley floors, and with no incoming weather systems to stir up the atmosphere, those inversions are likely to persist for the foreseeable future. That also means there’s no snow in the forecast for the next 10 days unless there’s a dramatic shift in the jet stream, which will stay far to the north for the next week at least. Continue reading

New coral data traces 7,000 years of El Niño history

20th century oscillations show intensification that may be linked with global warming

El Nino graphic

A NOAA graphic showing early January 2012 ocean surface temperature anomalies.

By Summit Voice

SUMMIT COUNTY — Atmospheric scientists say they’ve used coral records to trace the history of El Niño cycles going back about 7.000 years, showing that 20th century oscillations  are much stronger than those captured in the fossil record.

But the study also showed large natural variations in past ENSO strength, making it difficult to attribute the 20th century intensification of ENSO to rising carbon dioxide levels. Such large natural fluctuations in ENSO activity are also apparent in multi-century climate model simulations, but the 20th century intensification stands out as statistically significant and could be linked with global warming.

The new information will help assess the accuracy of climate model projections for 21st century climate change in the tropical Pacific. Continue reading

Colorado: Mostly dry into December

Is Colorado facing more drought?

So far, the pattern of storms across the Pacific Northwest and northern Rockies shows little signs of changing, with most of the weather action far north of Colorado.

By Bob Berwyn

FRISCO — Ullr, why has thou forsaken us?

If you’re holding out for more snow before heading out to make turns on the hill, you may want to reconsider. The outlook for the next 10 days is mostly dry and warm, with perhaps a chance of snow brushing the northern mountains Sunday night into Monday morning. Beyond that, another ridge will build into the Southwest, bringing more dry weather and a return to above normal temps for much of next week. Continue reading

Climate: Parts of the tropical Pacific Ocean are shifting toward a permanent El Niño-like pattern

Archived ocean observations help create new data set for climate models

Atmospheric circulation patterns drive convection in the tropics and can have a far-reaching effect on global climate. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — A new set of more complete sea surface temperature data has helped scientists explain a gradual, decades-long slowdown of a key tropical atmospheric circulation, linking it with the steady increase in global temperatures during the past few decades.

“Our experiments show that the main driver of the change in the Walker circulation is the gradual change that has taken place in the surface temperature pattern toward a more El Niño-like state,” said Hiroki Tokinaga, associate researcher at the International Pacific Research Center, University of Hawaii at Manoa. “We don’t have enough data yet to say to what degree the slowdown over the last 60 years is due to a rise in man-made greenhouse gases or to natural cycles in the climate,” Tokinaga said.

The Walker circulation determines much of the tropical Indo-Pacific climate and has a global impact as seen in the floods and droughts spawned by the El Niño-Southern Oscillation. Meteorological observations over the last 60 years show this atmospheric circulation has slowed: the trade winds have weakened and rainfall has shifted eastward toward the central Pacific. Continue reading

Climate: NOAA drops El Niño watch

Forecasters call for neutral conditions, but say a La Niña is not out of the question

n El Niño never managed to establish itself in the equatorial Pacific this year.

The three-month precipitation outlook from NOAA’s Climate Prediction Center.

By Summit Voice

FRISCO — With sea surface temps cooling to near average in much of the equatorial Pacific, NOAA’s Climate Prediction Center has dropped an El Niño watch that’s been in effect for the past several months.

El Niño is part of a cyclical pattern of sea surface temperature variations that affects global weather patterns. The emerging El Niño forecast last spring and summer offered some hope for drought relief in the parched Southwest and the southern tier of states, where warmer than average Pacific Ocean temps can help boost winter and spring precipitation.

During La Niña years, when cooler-than-average sea surface temperatures prevail in the same region, the storm track often shifts northward, driving storms into the Pacific Northwest and then down across the northern Rockies and northwest Colorado. Continue reading

Colorado snowpack off to a poor start

Precipitation lagging behind last year

Last year’s line is green; this year’s is orange.

By Summit Voice

FRISCO — It’s still early in the season, but so far, this year’s snow pack in Colorado is running behind even last year’s meager totals for this time of year, as the little bit of snow that fell last month melted away some of the SNOTEL sites.

The Copper Mountain SNOTEL site was reporting 4 inches of snow a few weeks ago, but is now back to zero, for example, and numerous other SNOTEL sites are also reporting at zero.

Exceptions are in the far north, where the Tower site is reporting 5 inches on the ground, and the Never Summer site, leading the state with 10 inches. Grizzly Peak is reporting 3 inches, while Fremont Pass is at 4 inches. Continue reading

Colorado: Forecasters still grappling with winter outlook

An El Niño often brings decent October precipitation to the high country, but signals are mixed this year.

No clear signal means water managers will be biting their nails for a few months

By Bob Berwyn

FRISCO — Without a strong El Niño or La Niña signal, Colorado weather watchers are struggling even more than usual to get a sense of how much snow to expect this coming winter, critical information for water managers who have seen reservoir storage dwindle to below 70 percent of average for this time of year.

Even if winter snowfall is close to normal, some reservoirs are unlikely to refill completely next spring, leaving utilities in the position of hoping for an above average winter.

“We’re far from through this. The story has yet to unfold,” Blue River Basin water commissioner Troy Wineland said after participating in a weekly statewide water webinar, explaining that many local streams are flowing well below seasonal averages. A few others are close to average due to upstream releases of stored water, he said. Continue reading

Summit Voice: Weekend headlines & most-viewed stories

Climate costs, ski area expansions and poaching

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Study challenges pesticide link with bee colony collapse

Honeybees may be dying from ingesting remnants of insecticides, but that in itself may nor be causing the widespread colony collapse being observed in many areas, according to new research published in the journal Science.

Study: Many nuclear power plants in tsunami risk zones

The Fukushima disaster might not be the last time a tsunami damages a nuclear facility, according to a team of Spanish researchers who there are a total of 23 nuclear power plants at various stages of operation or construction in high-risk areas.

Colorado biologists planning statewide lynx assessment

Colorado Parks and Wildlife biologists say they’re close to finalizing a plan to monitor the state’s lynx population by assessing habitat occupancy. If successful, the strategy would enable researchers to determine whether the population of endangered wild cats is sustaining itself over time.

Climate: Ice-free Arctic ahead?

SUMMIT COUNTY — Despite a steady trend of melting Arctic sea ice, experts with the National Oceanic and Atmospheric Administration aren’t yet willing to make any predictions as to when the region will be completely ice-free during the summers.

Colorado: Elk poacher hit with $11,500 fine

SUMMIT COUNTY — A West Virginia man will pay an $11,500 fine for poaching Colorado wildlife. The fine includes a $10,000 penalty that applies when trophy-quality wildlife is poached — in this case a 6×6 bull elk taken on Devil’s Thumb Ranch property in Tabernash earlier this month.

World Tourism Day focuses on sustainable energy

SUMMIT COUNTY — In an era when reducing greenhouse gas emissions has been targeted as a critical priority, it’s more challenging than ever to reconcile tourism with environmental concerns.

Climate: El Niño stalls, outlook uncertain

SUMMIT COUNTY — This year’s El Niño is likely to be one of the weaker versions of the event in recent memory, according to experts with the National Climatic Data Center, who discussed the fall outlook and reviewed the long, hot summer at teleconference last week.

Global tourist visits on track to pass 1-billion mark

FRISCO — Travelers from some of the world’s biggest countries helped spur global tourism to a new record level during the first half of 2012, keeping the industry on track to pass the 1-billion mark for the first time this year.

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