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While much weaker than their Pacific counterparts, Atlantic Niñas can nonetheless partially counteract La Niña by weakening the summer winds that help drive upwelling that cools the eastern Pacific.
Why are both things happening now?
In July and August 2024, meteorologists cooling noticed what appeared to be the development of an Atlantic Niña along the equator. Ocean surface winds had been weak for most of the summer and sea surface temperatures there were Quite warm until early June.so the signs of the emergence of an Atlantic Girl came as a surprise.
At the same time, waters along the equator in the eastern Pacific were also cooling, with La Niña conditions are expected there in October or November.
Getting a Pacific-Atlantic Niña combination is rare but not impossibleIt’s like finding two different pendulums that are loosely coupled and swing in opposite directions moving together in time. Combinations of La Niña and Niño Atlántico, or El Niño and Niña Atlántico, are more common.
Good or bad news for hurricane season?
An Atlantic Niña may initially suggest good news for those living in hurricane-prone areas.
Colder than average waters off the coast of Africa may Suppressing the formation of African easterly wavesThese are clusters of thunderstorm activity which can lead to tropical disturbances and eventually tropical storms or hurricanes.
Tropical storms Extract energy from the process of water evaporation. Associated with warm sea surface temperatures, cooling in the tropical Atlantic could weaken this process, leaving less energy for thunderstorms, thereby reducing the likelihood of tropical cyclone formation.
However, NOAA takes all factors into account when Updates its forecast for the Atlantic hurricane seasonreleased in early August, and still anticipates an extremely active 2024 season. Tropical storm season typically peaks Early to mid-September.
There are two reasons behind this busy forecast: Almost record heat Warmer sea surface temperatures across much of the North Atlantic can strengthen hurricanes, and the projected development of a La Niña event in the Pacific tends to weaken them. wind shear—the change in wind speed with height that can break up hurricanes. The much stronger effects of La Niña can negate any impact associated with Atlantic La Niña.
Global warming worsens the problem
The last two years have seen exceptionally high ocean temperatures in the Atlantic and across much of the world’s oceans. The two Niñas are likely to help alleviate some of the cooling in certain regions, but this may not last long.
In addition to these cycles, the global warming trend caused by increasing greenhouse gas emissions is raising baseline temperatures and may fuel major hurricanes.