La Niña, the flip side of the better known El Niño weather condition, keeps popping up. La Niña is the natural but temporary cooling of parts of the Pacific that changes weather worldwide.
An Associated Press statistical analysis of winter La Niñas show that they used to happen about 28% of the time from 1950 to 1999, but in the past 25 winters, they’ve been brewing nearly half the time. There’s a small chance that this effect could be random, but if the La Niña sticks around this winter, as forecast, that would push the trend over the statistically significant line, which is key in science, said L’Heureux.
“At this point we just don't know,” L'Heureux said. “Scientists are watching and I know, are actively studying. But it’s really important because of regional conditions. We need to get this right.” The current La Niña formed in the late summer of 2020 when the Atlantic set a record for the number of named storms. It strengthened in the winter when the West’s drought worsened and in the early summer of 2021 it weakened enough that NOAA said conditions were neutral. But that pause only lasted a few months and by early fall 2021 La Niña was back, making it a double dip.
La Niña has its biggest effect in the winter and that’s when it is a problem for the West because it’s the rainy season that is supposed to recharge area reservoirs. But the West is in a 22-year megadrought, about the same time period of increasing La Niña frequency.