Strongest La Nina underway in a decade

ANCHORAGE, Alaska (KTUU) - Waters in the equatorial pacific continue to cool, making it the strongest La Nina since the winter of 2010-2011.

La Nina is part of the climate pattern known as El Nino Southern Oscillation, a scientific term that describes the oscillating temperature changes between the ocean and atmosphere in the Equatorial Pacific. La Nina is known as the cold phase while El Nino is known as the warm phase. Globally this has significant effects on jet stream patterns and therefore also on temperatures and precipitation amounts across the world, including in Alaska, but the effects haven’t been as noticeable locally so far this year.

“La Nina has not had too much of an effect on Alaska weather,” Alaska Climate Specialist Rick Thoman said in an interview with Alaska’s News Source. “The weather that we saw for instance in November and much of [December] is not what you would typically expect.”

According to Thoman, this isn’t surprising as most effects from La Nina aren’t felt in the state until later in the winter, however, the lack of sea ice is tilting parts of the state away from a typical La Nina pattern. The long-term outlook does account for that though, as the Climate Prediction Center has tilted the odds towards a warmer winter for portions of western and northwest Alaska.

“Nowadays we have very different conditions in the oceans than we had in past La Ninas,” Thoman said. “Bering Sea ice extent right now is extremely low and is going to stay that way for a little while at least, with all the storminess out there.”

Storms like the record-breaking low at the tail end of 2020 consistently churn the waters and eat away at the thin or young ice that does manage to form. This essentially leaves more open water and warmer temperatures along the western coast, despite a strong La Nina.

While we’ve only seen a handful of days so far this winter with below normal temperatures. Thoman says the odds favor below normal temperatures, which he expects will be seen in the latter half of winter. Even amidst the strongest La Nina in a decade, Thoman says the weather in Alaska can still see a big flip in the weather pattern following one to two weeks of colder conditions.

“We’ll see what [2021] brings,” Thoman said. “If you don’t like the weather this week, wait a little bit and it’s likely to change.

For many, even when the cold settles in this winter, don’t expect it to last long. Thoman says that significant changes are underway in the Arctic that are leading to much of the state seeing an earlier spring due to premature snow loss and warmer months in a changing climate.