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New study shows link between Pacific sea surface temperatures and tornado patterns in the Midwestern U.S.

Cooler Pacific Ocean temps may drive tornado activity into southern U.S.

A tornado near Lakeview, Texas. Photo courtesy NOAA.

A tornado near Lakeview, Texas. Photo courtesy NOAA.

By Summit Voice

FRISCO — After studying more than 56,000 tornados, researchers at the University of Missouri say they’ve found a clear link between Pacific Ocean sea surface temperatures and the patterns of storms that spawn the violent twisters. The findings could help scientists predict the type and location of tornado activity in the U.S.

When surface sea temperatures were warmer than average, the U.S. experienced 20.3 percent more tornadoes that were rated EF-2 to EF-5 on the Enhanced Fuijta (EF) scale. (The EF scale rates the strength of tornados based on the damage they cause. The scale has six category rankings from zero to five.)

“Differences in sea temperatures influence the route of the jet stream as it passes over the Pacific and, eventually, to the United States,” said Laurel McCoy, an atmospheric science graduate student at the MU School of Natural Resources. “Tornado-producing storms usually are triggered by, and will follow, the jet stream. This helps explain why we found a rise in the number of tornadoes and a change in their location when sea temperatures fluctuated.” Continue reading

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Global June temps the 5th-warmest on record

Many northern hemisphere land areas reported near-record warmth

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Most areas of the globe reported temperatures running well above the 20th century average during June 2013.

By Summit Voice

FRISCO — The Globally averaged land and sea surface temperature was 1.15 degrees above the 20th century average, tying with 2006 as the fifth-warmest on record, according to the National Climatic Data Center monthly summary report released this week.

The average land-surface temperature was even warmer. At 1.89 degrees above average, it was the third-warmest June on record over the world’s land areas. Record-setting warmth was reported from many locations in northern Canada, far northwestern Russia, southern Japan, the Philippines, part of southwestern China, and central southern Africa.

The year to-date is also running hot, tied with 2003 as the seventh-warmest January to June period on record, with a combined global land and ocean average surface temperature that was 1.06 degrees above the 20th century average. Continue reading

Global warming: Will wet regions get even wetter?

New research focuses on tropical rainfall changes

IDL TIFF file

A NASA GOES satellite image shows the intertropical convergence zone.

By Summit Voice

SUMMIT COUNTY — Researchers say they’re getting closer to mapping how global warming will change rainfall patterns across the tropics. Their models project increases in precipitation in areas that already wet, and also in regions where temperatures increases surpass the average warming of the tropics.

“Because our present observations of seasonal rainfall are much more reliable than the future sea surface temperatures, we can trust the models’ projections of seasonal mean rainfall for regional patterns more than their annual mean projections,” said University of Hawaii meteorologist Shang-Ping Xie. “This is good news for monsoon regions where rainfall by definition is seasonal and limited to a short rainy season. Many highly populated countries under monsoon influences already face water shortages.” 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: El Niño stalls, outlook uncertain

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.

Could cloud-seeding weaken hurricanes?

Researchers propose cloud-brightening to avert strong storms

A composite NOAA image of Hurricane Andrew, in 1992.

By Summit Voice

SUMMIT COUNTY — While hurricanes are often feared as a destructive force of nature, they are also one of nature’s great climate regulators, helping to disperse ocean and atmospheric heat away from the equatorial region.

But some environmental scientists think it might be a good idea to reduce the intensity of hurricanes by seeding clouds to decrease sea surface temperatures when hurricanes form. Theoretically, the scientists claim the technique could reduce hurricane intensity by a category.

The team focused on the relationship between sea surface temperature and the energy associated with the destructive potential of hurricanes. Rather than seeding storm clouds or hurricanes directly, the idea is to target marine stratocumulus clouds, which cover an estimated quarter of the world’s oceans, to prevent hurricanes forming.

“Hurricanes derive their energy from the heat contained in the surface waters of the ocean,” said Dr Alan Gadian from the University of Leeds. “If we are able to increase the amount of sunlight reflected by clouds above the hurricane development region then there will be less energy to feed the hurricanes.” Continue reading

Climate: Global July temps the 4th-highest ever

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.

Climate: New research may enable earlier El Niño forecasts

Most El Niños since 1958 began with a previously unidentified subsurface discharge of warm water about 18 months before the peak of the events

A NOAA graph of June 25 sea surface temperature anomalies shows a spear of warm water spreading east from South America along the equator.

By Summit Voice

SUMMIT COUNTY — Not every El Niño is the same, but all of them start with a massive discharge of sub-surface warm water from the equatorial western Pacific.

That discharge starts much earlier than previously recognized, and may provide an early warning for the onset of El Niños, which can affect much of the world with weather anomalies, including flooding rains in some places and drought in other areas. It’s also seen as a mechanism for recharging the tropics with warm water.

The new El Niño study was authored by Nandini Ramesh and Raghu Murtugudd, associated with the University of New South Wales Climate Change Research Centre and published in the journal Nature Climate Change.

The scientists studied El Niño episodes between 1958 and 2011 to try and find a pattern. In the process, they showed that El Niños in the 1980s and 1990s started with warm sea surface temperature anomalies near the dateline that spread eastward, while earlier episodes started with anomalies off the west coast of South America and spread to the west. Continue reading

More evidence that global warming drives extreme weather

Extreme Queensland floods linked with evaporation from high sea surface temperatures

Global warming could drive a more active storm pattern in the Atlantic.

By Bob Berwyn

SUMMIT COUNTY —There’s been a lot of discussion recently about how TV weather forecasters handle the issue of global warming — to the point that a watchdog group — ForecastTheFacts.org —  has started singling out what it sees as the worst offenders in the forecasting community.

Some of those high-profile weathermen in big market cities have a responsibility to tell viewers more about the emerging science that shows how a warming planet will affect day-to-day weather, including the potential for more frequent and severe storms, extended periods of drought and other extremes.

The group takes issues with statements like these, from John Coleman, of KUSI-TV in San Diego, who said, “Our crops and our forests are thriving because of carbon dioxide,” when, in fact, a warming climate has been at least partially responsible for a destructive wave of insect pests and forest fires that have devastated forests across the West. Continue reading

Climate: NOAA issues La Niña advisory

Drought may continue across south-central U.S.

La Niña is credited with delivering above average snowfall to parts of the Rockies last winter.

Last winter's La Niña brought plentiful snow to Colorado from November through May.

By Summit Voice

SUMMIT COUNTY — It’s official — La Niña is back, according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center, which last week upgraded its La Niña watch to a La Niña advisory.

“This means drought is likely to continue in the drought-stricken states of Texas, Oklahoma and New Mexico,” said Mike Halpert, deputy director of the Climate Prediction Center. “La Niña also often brings colder winters to the Pacific Northwest and the northern Plains, and warmer temperatures to the southern states.” Continue reading

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