La Nina has arrived, threatening even bigger blazes and storms

Boston: The extreme weather that has hammered California, Oregon and Washington state with runaway wildfires and hit Louisiana with its most powerful hurricane in 160 years may be about to get even worse.

La Nina — a phenomenon that occurs when the surface of the Pacific Ocean cools — has officially formed, the US Climate Prediction Centre said on Thursday, US time. It triggers an atmospheric chain reaction that stands to roil weather around the globe, often turning the western US into a tinder box, fuelling more powerful hurricanes in the Atlantic and flooding parts of Australia and South America.

"We're already in a bad position, and La Nina puts us in a situation where fire-weather conditions persist into November and possibly even December," said Ryan Truchelut, president of Weather Tiger, a forecasting service. "It is exacerbating existing heat and drought issues."

Wildfires devastated parts of Talent, Oregon, on Thursday.Credit:AP

The effects are already evident. Rising temperatures and an extreme mega-drought across the US West are fuelling fires from Washington to Arizona. Oregon bore the brunt of nearly 100 major wildfires ripping across the western states and major loss of life was expected about several towns were destroyed. California is having its worst fire season on record and in the Atlantic a record number tropical storms have formed by September, including hurricane Laura, which killed more than a dozen people across the Caribbean and the US last month.

The first half of 2020 was already quite hot — just 0.05 degrees Celsius lower than the record set in 2016, according to the National Centres for Environmental Information in Asheville, North Carolina. The odds are high 2020 will end up in the top five warmest years ever.

A street in West Linn, Oregon, is shrouded in smoke from wildfires.Credit:Christian Gallagher/AP

Across the 11 Western states, nearly 87 per cent of the landscape was abnormally dry, a slight up tick from a week ago, the US Drought Monitor said. More than half of California is in drought.

La Nina doesn't just mean more heat. It also raises the chances for a colder winter across the northern US and increases the prospects of floods in northern Australia and more rain in Indonesia and in Brazil's three southern most states.

California's rainy season typically starts by early winter, and can counter the fire-spreading Santa Ana winds that are starting now. But if La Nina gets in the way, it could have dire consequences for the state where fires have already charred more than, torching an unprecedented 2.5 million acres (more than 1 billion hectares), the most on record, and 80 per cent of the land is abnormally dry.

"It can create a ripple effect over North America," said Michelle L'Heureux, a forecaster with the Climate Prediction Centre in College Park, Maryland.



In the Atlantic, having La Nina develop in the last three months of hurricane season could mean more storms of greater power. This year's 17 named storms make for the quickest that tally has been reached in data going back to 1851, well above the annual average of 12.

The Climate Prediction Centre forecast in August that there would be 19 to 25 Atlantic storms this year, based in part on the potential for La Nina to appear.

Bloomberg

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