What is La Niña? Experts explain how the weather pattern can affect your winter plans
This winter’s La Niña forecast could bring more snow than usual to the northwestern United States and drier, warmer weather to the south.
But Northeastern University professor Samuel Munoz said he would be wary of planning skiing or beach vacations near La Niña, a periodic weather pattern caused by the cooling of the Pacific Ocean.
“Not all La Niña events are the same,” said Muñoz, an associate professor of marine and environmental science at the Northeastern Institute for Coastal Sustainability.
“Depending on where you live, the odds are just that your winter will be warmer or colder, wetter or drier than usual.”
“The conditions in the tropical Pacific, whether it’s La Niña or El Niño, give you a vague idea of what the situation is like, but it’s not definitive.”
El Niño vs La Niña
La Niña is part of a climate system called the El Niño Southern Oscillation, which oscillates between El Niño and La Niña phenomena, Muñoz said.
He said El Niño occurs when temperatures in the central and eastern Pacific Ocean are warmer than normal, while La Niña occurs when that part of the Pacific Ocean is cooler than normal.
According to the National Oceanic and Atmospheric Administration, winter temperatures across the continental United States during an El Niño event are warmer than normal in the North Central states and colder than normal in the Southeast and Southwest.
“Winter temperatures in La Niña years are above normal in the Southeast and below normal in the Northwest,” NOAA said. NOAA has published maps of average precipitation and average temperatures across the United States during strong La Niña events.
A new understanding of ancient patterns
The El Niño/La Niña Oscillation is an ancient climate pattern, but Western scientists only recognized it in the 1980s, Muñoz said.
“This phenomenon has only really been understood in the last few decades, but it impacts weather and climate across the globe,” he says.
Observed for years by fishermen off the coasts of Chile, Peru, and Ecuador, El Niño, which means “little boy” in Spanish, refers to the pronounced changes in water temperature around Christmas in late December that are associated with the Christ Child. It can also point.
During El Niño, trade winds that blow from east to west weaken, but the reason for this is not fully understood, Muñoz said. “Rather than moving forward, the warm water accumulates in the eastern Pacific Ocean.”
He said that during a La Niña phenomenon, which means “girl” in Spanish, trade winds can become so strong that they can push Pacific ocean waters westward, creating cold water springs.
Who is affected by La Niña?
NOAA maps show that states in the Northwest and Upper Midwest experience colder temperatures and more precipitation on average during La Niña winters, while southern states from Texas to Florida experience warmer, drier weather. is recorded.
Muñoz said the regions are separated by the jet stream, a fast-moving band of air that moves through the upper atmosphere of the northern and southern hemispheres and is pushed in different directions by El Niño and La Niña.
He said La Niña impacts climate conditions in parts of Africa and Asia, but less so in Europe and New England states, which are more influenced by Atlantic weather patterns.
While NOAA maps show somewhat wetter and colder conditions in certain parts of western Massachusetts and Maine this winter, Muñoz said the impact on New England in general will be “pretty negligible.” ” states.
“The relationship between the region’s climate and the overall phenomenon (El Niño and La Niña) is not very strong,” he says.
drought and flood
Although most La Niña events are not sufficient to cause catastrophic weather conditions on their own, they can contribute to environmental phenomena.
“We didn’t know this in the 1920s and 1930s, but now we know that the Dust Bowl drought was associated with La Niña,” Muñoz said.
His own research shows that as El Niño brings wetter winters to some states, the Mississippi and Missouri rivers are more likely to flood.
The effects of the El Niño/La Niña oscillation are felt more in the winter than in the summer, but Munoz said they haven’t been felt yet this year.
“Last year we briefly moved into El Niño conditions, and now we’re predicted to enter a weak La Niña. We’re really in neutral territory now,” he says.
Muñoz said scientists are trying to figure out how climate change will affect the vibrations.
“There are some studies that suggest that as the greenhouse effect progresses, the variation between these two states will increase and the switch from one to the other will occur more quickly,” Muñoz says.
“But that’s just one example. In my opinion, this is still an open question,” he says.
Muñoz said El Niño and La Niña are “totally normal phenomena that have been occurring for a long time, as long as we’ve had the Pacific Ocean, as far as we know.”
Provided by Northeastern University
This article is republished courtesy of Northeastern Global News news.northeastern.edu.
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