La Niña has arrived and will continue. Here’s what it means for the dry southwest and American hurricanes

La Niña typically brings conditions that are wetter and cooler than average to the northwestern and northern plains of the Pacific Ocean, especially in winter.

In contrast, La Niña means that dry and warmer-than-average conditions usually prevail in the south. This may mean that the drought-stricken southwest is likely to remain dry. (La Niña was also present last winter, exacerbating the drought throughout the west and southwest.)

The southeast is also typically drier during a La Niña winter, but before the season starts, it increases the possibility of tropical weather, including hurricanes.

La Niña will continue through the winter in the United States

La Niña – translated from Spanish with “little girl” – is a natural ocean-atmospheric phenomenon characterized by cooler than average sea surface temperatures over the central and eastern Pacific Ocean near the equator, which consequently affects the weather around the world.

“La Niña is expected to affect temperature and precipitation across the United States over the coming months,” the center said as it issued an advisory Thursday in La Niña predicting conditions are present and expected to remain.

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The advice replaces the La Niña watch, which set favorable conditions for development that had been in place since July.

NOAA announces its winter outlook on October 21, and the presence of La Niña is expected to weigh heavily in the forecast for the season. The prediction center put the odds close to 90% that La Niña would be in place through the winter of 2021-2022.

Both La Niña and El Niño occur on average every three to five years, according to NOAA.

La Niña’s impact on the rest of the hurricane season

During La Niña, weaker winds between the sea surface and the upper levels of the atmosphere affect global jet streams and can affect the trail and severity of winter storms and hurricanes in the warmer months.

“La Nina is associated with reductions in vertical wind cutting in the Caribbean and the tropical Atlantic,” said Phil Klotzbach, a researcher at Colorado State University. “Too much shift is typically what ends the Atlantic hurricane season, so La Niña can extend the active part of the season.

“Last year is a good example of this, as we had six hurricanes and five major hurricanes in October-November,” he said. “While we certainly don’t expect to see that much activity the rest of this season, the development of La Niña leaves the window open for more storm activity in the late season this year.”

At the start of this hurricane season, seasonal forecasters said to watch out for La Niña formation in October because it could make the second half of the season active.
Currently, conditions across most of the Atlantic are not conducive to hurricane formation. But this may change in the coming weeks.

La Niña and the climate crisis

While El Niño and La Niña events are regular aspects of global weather patterns, rising global temperatures can temper or alter their effects.

La Niña tends to pull down global temperatures, but in recent years the planet has become so fast that it’s like hitting a small speed bump at 80 km / h – it hardly even detects.

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It is probably too early to know how climate change will affect these patterns; research is beginning to show how a warming climate can amplify the effects of El Niño and La Niña. Climate change may increase the severity of weather events stemming from El Niño and La Niña patterns, according to a 2018 study on atmospheric conditions that ran simulations of climatic conditions.

Top places on the list of the warmest years used to be reserved for the strong El Niño years, but human influence has long since overwhelmed the planet’s natural temperature regulators. For example, La Niña was present in parts of 2020, but the year was still tied with 2016 (an El Niño year) as the hottest ever on the planet.

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