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

Posted on November 15, 2012 by Bob Berwyn

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. (more…)

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Climate: NOAA drops El Niño watch

Posted on November 11, 2012 by Bob Berwyn

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. (more…)

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Colorado: Forecasters still grappling with winter outlook

Posted on October 17, 2012 by Bob Berwyn

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. (more…)

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

Weather: El Niño, or La Niña’s ghost?

Posted on October 8, 2012 by Bob Berwyn

El Niño still struggling to develop

Will a negative Pacific Decadal Oscillation influence Colorado’s winter weather? Graphic courtesy NASA.

The three-month precipitation outlook from the Climate Prediction Center.

By Bob Berwyn

SUMMIT COUNTY — Climate experts are still hedging their bets when it comes to an outlook for the coming winter, with the official outlook from NOAA’s Climate Prediction Center showing no strong trend toward above- or below-average precipitation.

A somewhat murky El Niño outlook is clouding the picture, with sea surface temperatures in the equatorial Pacific ranging above average, but cooling down from just a month ago.

“It’s vexing … the models are just not up to the task,” Wolter said. Overall, he said he’s “guardedly optimistic” that Colorado will see at least close to an average snowfall year, which would would be critical to maintaining water supplies in the state’s depleted reservoirs. (more…)

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Climate: El Niño stalls, outlook uncertain

Posted on September 23, 2012 by Bob Berwyn

Above-average temperatures to persist across much of the country

Sea surface temperature anomalies as of Sept. 20. Graphic courtesy NOAA.

By Bob Berwyn

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.

That could weaken potential impacts, particularly across the southern tier of states, where an “average” El Niño often brings above-average precipitation.This could be especially important for states like New Mexico, which just experienced its driest and warmest 24-month period on record, and farther east, where Oklahoma was also parched during a record-hot summer.

During an El Niño, sea surface temperatures in the eastern and central equatorial Pacific surge to above average, often shifting the storm track to the south. It’s part of a cyclical shift in sea surface temperatures and related wind patterns that can affect weather patterns worldwide.

Sea surface temps have hovered at slightly above average the past few months in the region where El Niño formation is measured, but haven’t reached the formal threshold yet. An area of cooler water in the north Pacific may be a factor.

The North Pacific is not cooperating … there’s a cold area near Alaska. It’s not quite a perfect setup for a warm event in the tropics,” said NOAA scientist Huug van den Dool.

“It’s probably too late to get a major El Nino … it’s going to be somewhat weaker than we expected a few months ago,” he said, explaining that there’s still a chance for enhanced precipitation across the South. An average El Niño footprint would normally also result in below-average precipitation in the northern tier of states.

A map from the National Climatic Data Center shows where the summer heat wave was centered. Click on the graphic to visit the NCDC online.

El Niño or not, the Climate Prediction Center says there’s a good chance the next three months will bring mostly above average temperatures to a big swath of the country, from the eastern edge of the Great Basin through the central and northern plains, up into the Great Lakes region and New England.

The three-month precipitation outlook is for near-normal total for much of the country, with a chance of above-normal rainfall in the southeast, and drier-than-normal conditions in the Pacific Northwest.

Looking back, Jake Crouch, of the NCDC, said it was the third-warmest summer on record for the U.S. and second-warmest summer for the northern hemisphere. A total of 33 states reported their warmest year to-date on record.

The year to-date is the ninth-warmest on record globally.

Filed under: climate and weather, Colorado, Drought, El Niño, Snow and weather, Summit County snow and weather | Tagged: , , , , | 1 Comment »

Wildfire activity surges past 10-year average

Posted on September 5, 2012 by Bob Berwyn

Fire risk expected to continue in northern Rockies

Monthly outlook

By Summit Voice

SUMMIT COUNTY — Wildfire activity across the U.S. has surged past the 10-year rolling average in the past few weeks, with major fires still burning in the northern Rockies, as well as the potential for big fires in the far West, as California hits the peak of the dry season.

Nationally, wildfires have now burned across about 7.6 million acres, more than last year’s total of 6.9 million acres, when massive fires scorched Texas and part of the Southwest.

This year’s total is the highest since 2006 (7.6 million acres) and nearly 2 million acres more than the 10-year rolling average of 5.9 million acres. (more…)

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Colorado: Does El Niño bring early snow?

Posted on August 27, 2012 by Bob Berwyn

Historical stats don’t show big impact on date of first snow

Summit County and a small surrounding area dodged the drought bullet in late July and early August, with rainfall anywhere from 130 to 200 percent of normal, but rainfall maps show that most of the state still experienced well-below average rainfall during that span.

A similar pattern was evident for the three-month precipitation history in Colorado, with just a few pockets of above-average rainfall in the north-central mountains and the western San Juans.

SUMMIT COUNTY — Talk about living in a bubble — the latest three-month summary and outlook from the National Weather Service in Boulder shows that the rainy conditions in Summit County, and a small surrounding area, were the exception in Colorado the past 30 days. Much of the state continued to suffer through extremely dry conditions, especially the eastern plains, where precipitation was just 5 to 50 percent of normal. As a result, much of the state is still experiencing serious drought. Visit the Boulder NWS website to see the full power point presentation. (more…)

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Global warming will shift South Pacific rain band

Posted on August 17, 2012 by Bob Berwyn

A 2004 NASA satellite image shows a volcano erupting on Vanuatu, in the South Pacific.

Island nations can expect to see more drought and flooding

By Summit Voice

SUMMIT COUNTY — Already under the gun from rising sea levels, some South Pacific island nations could also be swamped by more extreme floods and hit by drought as global temperatures rise in response to more heat-trapping greenhouse gases in the atmosphere.

The international study, led by CSIRO oceanographer Dr. Wenju Cai, examines how the South Pacific rain band will respond to greenhouse warming.

The South Pacific rain band is largest and most persistent of the Southern Hemisphere, spanning the Pacific from south of the Equator, south-eastward to French Polynesia. Occasionally, the rain band moves northwards towards the Equator by ip to 1,000 kilometers, inducing extreme climate events. (more…)

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Climate: Global July temps the 4th-highest ever

Posted on August 15, 2012 by Bob Berwyn

Cooler than average readings reported from Australia, South America

Red areas mark above-average temperatures, with blue designating areas that were cooler than average in July.

SUMMIT COUNTY — Already on record as the hottest month of all time in the U.S., July 2012 will now go into the books globally as the fourth-warmest on record.

According to the global temperature analysis released today by the National Climatic Data Center, the average combined land and sea surface temperature for July was 1.12 degrees above the 20th century average. The land surface temperatures alone was the third-warmest on record at 1.66 degrees above the 20th century average.

Last month marked the 36th consecutive July with above-average temperatures and the 329th consecutive month overall with higher-than-average readings. According to the NCDC, the last time July global temps were below average was in 1976.

The warmest temps were reported from southeastern Europe, Canada and the U.S. Much cooler than average temperatures continued in Australia, northern and western Europe, eastern Russia, Alaska, and southern South America.

Even in a transition phase between a cooling La Niña and an emerging El Niño, global ocean temperatures were well above normal, with the highest monthly departure from average since July 2010.

For the year to-date, the combined average land and sea surface temperature is the 10th-warmest on record.

Information compiled from the NOAA National Climatic Data Center, State of the Climate: Global Analysis for July 2012, published online August 2012, retrieved on August 15, 2012 from
http://www.ncdc.noaa.gov/sotc/global/2012/7
.

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Colorado: Monsoon brings some drought relief

Posted on July 23, 2012 by Bob Berwyn

Some mountain weather stations reporting above-average July rain

Parts of Colorado saw significant rainfall in the first half of July.

By Summit Voice

SUMMIT COUNTY — July rainfall through the middle of the month was well above average at many mountain weather stations, with Dillon, for example, reporting 1.94 inches through July 17, more than twice the average .92 inches. Estes Park and Georgetown both reported about triple their average rainfall amounts for the period, but drought conditions still persist across much of the state.

But for the year to-date, Dillon is still more than 2 inches off the pace, with total precipitation at 64 percent of average. Estes Park is down more than 5 inches for the year to-date, at 43 percent of average, and Georgetown is down almost 4 inches, at 59 percent of normal.

Thanks to the rain, drought conditions were downgraded from exceptional to extreme in southwest Jackson and northwest Grand counties, but even with the monsoon precipitation extreme drought conditions persisted across north-central and northeast Colorado.

Here’s why: In between rainstorms, temperatures remained well above average, resulting high rates of evapotranspiration, continuing to decrease soil moisture. In the hardest-hit areas, about 45,000 acres of crops, mainly wheat, have completely failed. Some farmers in northeast Colorado have abandoned alfalfa fields to save water from corn. (more…)

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