Another La Niña winter likely in the Northwest

September 24, 2021 5:51 PM

Matt Gray,

Posted: September 24, 2021 5:51 PM

Updated: September 25, 2021 1:22 PM

by Matt Gray

SPOKANE, Wash.– The phrase “La Niña winter” is music to the ears of snow lovers, ski operators, and drought-stricken farmers across the Northwest.

The winter of 2020-2021 didn’t quite live up to the hype though. It was wet, but also warm. That left snow totals looking more lackluster even though it was a fairly wet season. In Spokane, the 50.1 inches of snow last winter was five inches above average. That pales in comparison to other La Niña years like 2008 and 2009 where Spokane got more than 90 inches of snow.

La Niña is part of an ocean/atmosphere climate cycle known as ENSO. As temperatures warm and cool across the tropical Pacific Ocean, the weather above that stretch of ocean changes too. That in turn has ripple effects on weather across the world that are backed up by decades of research. When East Pacific waters are unusually cool, it’s known as La Niña, but if they’re unusually warm it’s known as El Niño. The Pacific has been mostly in La Niña conditions over the past year. It’s only warmed to the neutral phase of ENSO this spring and summer. Forecasts now give a 70 to 80 percent chance of more La Niña conditions developing this winter.

1200px Sea Surface Temperature November 2007

Sea surface temperature anomalies associated with La Niña

La Niña’s effects in the Inland Northwest are well documented. Ten to 25 percent more snow falls on average during a La Niña winter. Temperatures usually average colder than years with El Niño or neutral conditions. However, weak La Niñas like last year don’t dominate the winter weather patterns as stronger ones do. The latest NOAA forecasts say another weak La Niña is the most likely scenario this winter.

There is some encouraging information though for when La Niña winters come back-to-back in our area. There are 10 sets of consecutive La Niña winters in the last 70 years. Six of those “second” winters had more snow than the year before and seven were colder than the year before.

This is where things get difficult! La Niña isn’t the only factor in predicting how the winter is going to go. If forecasting the results of winter (cold and snow) are like baking a cake, you won’t be able to give a full picture with just one ingredient. That said, ENSO is one of the most important ingredients in this process. NOAA will be releasing their official winter outlook next month which will give us a more complete picture of what to look for once December rolls around.