La Niña’s back and it’s not good for the dry western part.


For the second year in a row, the world is heading for a new La Niña meteorological event. This tends to dry parts of the already dry and fiery western United States and boost the already busy Atlantic hurricane season.

Only five months after the end of the La Niña phenomenon, which began in September 2020, the US National Oceanic and Atmospheric Administration announced that new cooling of the Pacific Ocean was underway.

The natural cooling of parts of the Pacific Ocean in La Niña is behind the warmer El Nino pattern, which changes the world’s weather over months and sometimes years. However, changes vary from place to place and are not certain, they are just trends.

According to a 1999 survey, La Niña is more likely to cause agricultural and drought damage to the United States than El Nino or neutral conditions. The study found that La Ninas generally cost US agriculture $ 2.2 billion to $ 6.5 billion.


How strong and how long will it last?

Mike Harpert, Deputy Director of the NOAA’s Center for Climate Prediction, said this is a 57% chance of becoming a moderate La Niña and only a 15% chance of being strong. He said the second year of consecutive La Ninas is usually not well measured until the first year, so it is unlikely to be as strong as last year.

The La Niña phenomenon is expected to continue until spring, Harpert said.

What does this mean for the West?

For the entire southern third of the country, especially in the southwest, La Niña often means drier and warmer weather. Western countries have experienced more than 20 years of megadrought and have deteriorated in recent years.

But for the northwest (Washington, Oregon, perhaps part of Idaho and Montana), the La Niña phenomenon means more likely relief from rain and drought, Harpert said.

“It’s good for them, but probably not so good for Central and Southern California,” Harpert said.


Ohio Valley and Northern Planes can be damp and cool. La Niña winters also tend to shift winter blizzards further north, but in places like the Mid-Atlantic coast, blockbuster blizzards often do not occur.

What about the Atlantic hurricane season?

During the La Niña phenomenon last year, the Atlantic set a record with 30 named storms. This year, without the La Niña phenomenon, the season is still busier than usual, with 20 named storms and only one name left unused on the list of major storm names: Wanda.

It’s been quiet for the past few weeks, but “I’m hoping it will recover again,” Harpert said. “Just because it’s quiet now doesn’t mean that the storm will continue from October to November.”

The La Niña phenomenon tends to make the Atlantic season more active, as one of the key factors in the formation of a storm is the wind near its peak. El Nino causes more crosswinds to decapitate the storm, while La Niña has less crosswinds, allowing storms to occur and grow.


What about the rest of the world?

Much of both Southeast Asia and northern Australia are moist in La Niña — and that is already clear in Indonesia, Harpert said. Central Africa and southeastern China tend to be dry.

It is expected to be cool in western Canada, southern Alaska, Japan, the Korean Peninsula, western Africa and southeastern Brazil.


Follow Seth Borenstein on Twitter. @borenbears.


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La Niña’s back and it’s not good for the dry western part

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