Washington’s upcoming winter is forecast to be average to slightly colder than usual, according to experts, as climate patterns steer the state’s weather.
One of those climate patterns is El Niño and La Niña, a weather phenomenon that occurs in the Pacific Ocean and can affect global weather. Here’s what the two weather patterns mean and how they will affect Washington this winter.
An historic La Niña
We’re in for another year of La Niña.
A La Niña occurs when the temperature of the sea is cooler than average in the Eastern Pacific, resulting in less evaporation, weaker storms and less moisture in the atmosphere, according to the National Oceanic and Atmospheric Administration. Its counterpart, El Niño, is when warm water moves toward the West Coast.
Matthew Cullen, a meteorologist at the National Weather Service in Seattle, said that this will be the third consecutive year with a La Niña weather pattern. It’s an extremely rare occurrence to happen three years in a row, Cullen said, with the only two times it’s happened since records began in 1949 being from 1973 to 1976 and 1998 to 2001.
La Niña conditions typically span about 9 to 12 months but can go as long as two years, according to NOAA.
“There’s a lot of things that come into play with that,” Cullen said on why La Niña is forecast for a third-straight winter. “But certainly, it’s unusual.”
According to the National Centers for Environmental Prediction’s Recent Evolution, Current Status and Predictions, La Niña will continue through the Northern Hemisphere from winter 2022 to 2023.
What does this mean for Washington?
Falling in line with what is predicted by the Farmers’ Almanac, Cullen said that Washington state would experience below-average temperatures, but it’s less clear how much precipitation Washington will get.
The northeast portion of Washington is forecast to see above precipitation, Cullen said, but the rest of the state could swing either way of the average precipitation line.
“The two times this has happened before, one of those, the winter of 75-76, was actually quite wet, whereas 2000-2001 was quite dry,” Cullen said. “So that might be another part of it; there are only a couple of examples to lean on. And there really isn’t a clear signal since they kind of split, they went both ways.”
The effect of a La Niña depends on the region. According to NOAA, a typical weather pattern during a La Niña is cool and wetter than average temperatures in the Pacific Northwest and warmer and drier than average weather in the southern U.S.