La Nina is part of a natural climate cycle that can cause extreme weather across the planet — and its effects vary from place to placeMICHIGAN, USA — The National Oceanic and Atmospheric Administration’s Climate Prediction Center says there is a 60% chance that a weak La Nina event will develop this autumn and could last until March.
La Nina is part of a natural climate cycle that can cause extreme weather across the planet — and its effects vary from place to place.Although there is no guarantee how this La Nina will play out, there are some general trends. Experts say northern parts of South America could see more rain than usual. Southern regions of the U.S. and parts of Mexico could be drier than average. The northern tier of the U.S. and southern Canada could be wetter than average.
La Nina is the cool phase of the El Nino-Southern Oscillation, a naturally occurring global climate pattern that involves changes in wind and ocean temperatures in the Pacific and can cause extreme weather across the planet.
El Nino is the warm phase and happens when trade winds that typically blow across the Pacific toward Asia weaken, allowing warm ocean waters to pile up along the western edge of South America. But during La Nina, the trade winds intensify and cold water from the depths of the sea rises up, resulting in cooler than average ocean temperatures in the eastern Pacific.
These cold ocean temperatures and changes in the atmosphere affect the position of the jet stream — a narrow band of fast moving air flowing from west to east around the planet — by bumping it northward. The jet stream sits over the ocean and can tap into its moisture, influence the path storms take and boost precipitation.
Just recently Earth experienced a “triple-dip” La Nina event from 2020 to 2023. “We had three back to back winters where we had La Nina conditions, which was unusual because the only other case of that happening was back in 1973 to 1976,” said Michelle L’Heurex, a climate scientist at NOAA. L’Heurex said that La Nina’s tend to last longer and be more recurrent than El Nino events.
“It’s unusual although it’s not unprecedented,” said Ben Cook, climate scientist at the NASA Goddard Institute for Space Studies affiliated with Columbia University, about the forecast for a possible La Nina this year.