El Nino Is Starting To Lose Strength After Fueling A Hot, Stormy Year, But It’s Still Powerful
An atmospheric scientist explains what’s ahead for 2024.
Wild weather has been for the past few months, thanks in part to a strong El Nino that sent temperatures surging in 2023. The climate phenomenon fed drenching the West Coast and contributed to in the South and Midwest and fall’s .
That strong El Nino is now and will likely be gone by late spring 2024.
So, what does that mean for the months ahead – and for the 2024 hurricane season?
What Is El Niño?
Let’s start with a quick look at what an El Nino is.
El Nino and its opposite, La Nina, are around the world. El Nino tends to raise global temperatures, as we saw in 2023, while La Nina events tend to be slightly cooler. The two result in global temperatures fluctuating above and below the .
El Nino starts as warm water builds up along the equator in the eastern tropical Pacific Ocean, off South America.
Typically, tropical Pacific winds blow from the east, exposing cold water along the equator and building up warm water in the western Pacific. Every , however, these winds relax or turn to blow from the west. When that happens, warm water rushes to the east. The warmer-than-normal water drives more rainfall and alters winds around the world. .
The water stays warm for several months until, ultimately, it cools or is driven away from the equator by the return of the trade winds.
When the eastern Pacific region along the equator becomes abnormally cold, La Nina has emerged, and global weather patterns change again.
What To Expect From El Nino In 2024
While the 2023-24 El Nino event , it is still strong.
For the rest of winter, forecasts suggest that strong El Nino conditions will likely continue to favor unusual warmth in Canada and the northern United States and occasional stormy conditions across the southern states.
El Nino is likely to end in late spring or early summer, shifting briefly to neutral. There’s a good chance we will see La Nina conditions this fall. But forecasting when that happens and what comes next is harder.
How An El Nino Ends
While it’s easy to tell when an El Nino event reaches its peak, predicting when one will end depends on how the wind blows, and everyday weather affects the winds.
The warm area of surface water that defines El Nino typically becomes more shallow toward spring. In mid-May 1998, at the end of an , there was a time when people fishing in the warm surface water in the eastern tropical Pacific could have touched the cold water layer a few feet below by just jumping in. At that point, it took only a moderate breeze to pull the cold water to the surface, ending the El Nino event.
But exactly when a strong El Nino event reverses varies. A didn’t end until July. And the retreated into the central Pacific but did not fully reverse until December.
As of early February 2024, strong westerly winds were driving warm water from west to east across the equatorial Pacific.
These winds tend to make El Nino last a little longer. However, they’re also likely to drive what little warm water remains along the equator out of the tropics, up and down the coasts of the Americas. The more warm water that is expelled, the greater the chances of full reversal to La Nina conditions in the fall.
Summer And The Hurricane Risk
Among the more important El Nino effects is its tendency to reduce .
El Nino’s Pacific Ocean heat affects upper level winds that blow across the Gulf of Mexico and the tropical Atlantic Ocean. That – the change in wind speed and direction with height – which can tear hurricanes apart.
The 2024 hurricane season likely won’t have El Nino around to help weaken storms. But that doesn’t necessarily mean an active season.
During the , El Nino’s effect on the winds was more than offset by abnormally warm Atlantic waters, which fuel hurricanes. The season ended with more storms than average.
The Strange El Nino Of 2023-24
Although the 2023-24 El Nino event wasn’t the strongest in recent decades, many aspects of it have been unusual.
It followed three years of La Nina conditions, which is unusually long. It also emerged quickly, from March to May 2023. The combination led to weather extremes unseen .
La Nina cools the tropics but stores warm water in the western Pacific. It also warms the middle latitude oceans by weakening the winds and allowing more sunshine through. After three years of La Nina, the rapid emergence of El Nino helped make the Earth’s surface .
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