As La Niña persists, here’s what forecasters are seeing for fall in Whatcom
It’s looking like Bellingham and Whatcom County can expect another rainy autumn, with a new forecast predicting a greater chance of above-normal precipitation for the next three months as the La Niña weather pattern continues into a rare third straight year.
That’s good news for winter-sports enthusiasts but a possibly ominous warning for those living in flood-prone areas of Whatcom County, where heavy rains in 2020 and 2021 caused more than $150 million in damage and forced hundreds of people from their homes.
With a week before the start of fall, the National Weather Service’s Climate Prediction Center issued its three-month outlook on Thursday, Sept. 15, calling for about a 40% chance of above-normal precipitation for Western Washington during the October-December period.
Those forecasts are based in part on a lingering La Niña weather pattern, a cooling of the Pacific Ocean off South America that is linked to cool, wet weather in the Northwest.
“During August, below-average sea surface temperatures persisted across the central and east-central equatorial Pacific Ocean,” the Climate Prediction Center said in a Sept. 8 report.
“Overall, the coupled ocean-atmosphere system continued to reflect La Niña,” the report said.
It concluded that there’s a 91% chance that La Niña will influence the Northwest’s weather into early next year.
October is the start of the rainy season in Western Washington.
Rainfall from October to November 2021 measured 23.05 inches, compared to a seasonal norm of 13.38 inches, according to National Weather Service data from Bellingham International Airport.
November 2021 rainfall of 14.57 inches was nearly triple the normal 5.2 inches for the month.
In 2020, rainfall from October to December was 16.55 inches, compared to a normal 13.69 inches.
“Normal” figures are based on 15-year averages and fluctuate annually.
A total of 704 inches of snow fell at the Mt. Baker Ski Area through April 24, including 122 inches in November 2021.
November flooding in the Whatcom County lowlands was caused in part by melting snow from a series of warm storms that dropped rain instead of snow in the North Cascades and sent torrents of water into an already swollen Nooksack River system.
