La Niña conditions are set to emerge again for the second straight winter, impacting the weather across the U.S. in the months ahead, the National Oceanic Atmospheric Administration says.
The climate pattern is part of the El Niño Southern Oscillation (ENSO) cycle, and is marked by below-normal sea surface temperatures in the Pacific Ocean near the equator, according to a NOAA news release.
The last La Niña developed in August 2020, with ENSO-neutral conditions returning around April 2021.
This La Niña would be what’s called a “double-dip,” meaning it’s the second consecutive time the climate pattern emerged after a transition to ENSO-neutral conditions in the tropical Pacific, NOAA stated the release.
However, it’s actually quite common for La Niñas to originate in back-to-back winters, experts say. The same is not true for El Niño, which develops in the eastern and central Pacific when sea surface temperatures are warmer-than-average. The last El Niño event began in 2018.
The potential development of another La Niña has been tracked since this summer by scientists, according to Mike Halpert, the deputy director of NOAA’s Climate Prediction Center.
“It was a factor in the above-normal hurricane season forecast, which we have seen unfold,” Halpert said in the release. “La Niña also influences weather across the country during the winter, and it will influence our upcoming temperature and precipitation outlooks.”
For Southern California, the weather phenomenon could unfortunately result in another dry winter for the already drought-stricken region.
“The southern tier during a La Niña is often drier than average during the winter, and that often extends into spring,” NOAA climate scientist Michelle L’Heureux said in August.
However, she added, that outcome is by no means certain.
“La Niña doesn’t mean anything absolutely,” L’Heureux explained. “Just saying there’s going to be a La Niña doesn’t mean it’s going to be dry and drought. We have certainly had La Niña winters where, lo and behold, there’s more precipitation than expected. That’s just less common.”
Current forecasts call for an 87% chance of La Niña conditions from December through February, before the pattern dissipates in the spring and ENSO-neutral conditions return, according to NOAA.
The agency is slated to release its winter outlook on Thursday.