PORTLAND, Ore. (KOIN) – Hello, winter. Are you awake? It’s January now, so where is the snow? I often catch myself with these thoughts and wonder if I should recalibrate my winter expectations.
So here is a quick refresher of what snowfall in Portland during the wintertime normally looks like, how our La Niña pattern has impacted our winter so far, and what the first half of January may bring to the lowlands.
The winter season has kicked off with zero snow events. Instead, December was a soggy month, bringing in over 5 inches of rain to Portland. Temperatures also ran warm. Average monthly temperatures were 3.5 degrees above-normal, mainly due to warm nights where overnight temperatures stayed in the mid to upper 40s.
Yet the odds for snowfall in Portland still remain good after the New Year. If the city sees snowfall, it will be during the coldest months: December, January and February. (And sometimes March, too.)
La Niña conditions are also expected to prevail throughout the winter season, which tends to provide cooler and wetter conditions across the Pacific Northwest. We haven’t seen much cooler weather yet, but what has been noticeable this December and January is the rain. Our storm track has stayed very active with a consistent string of weather systems slamming the West Coast.
Atmospheric rivers have also been prevalent this winter, which tend to bring in soaking rains over 24 hour periods. Portland saw record rainfall on Dec 20 when 1.43 inches fell during an atmospheric river event. Another event recently brought 1.06 inches of rain to Portland over the first weekend of January.
Lowland snowfall is hard to come by in atmospheric river events. These patterns tend to push in warm winds from the south, keeping temperatures in the lowlands in the 40s and low 50s.
Take a look at normal snowfall totals in Portland (Portland airport, KPDX).
December to January each has an average snowfall amount around 1.5 inches.
This seems promising – we’re entering the heart of winter. But looking at historical snow data in Portland since 1980 showed that La Niña winters tend to be a bit of a toss up instead of a season that screams lowland snow. They have provided relatively light and below-normal snow seasons in Portland, but also two of the last five major snow storms since 1980.
I wrote a deeper analysis of our current winter outlook. That can be found here.
The odds for lowland snowfall seem grim throughout the middle of January. Weather models keep the Pacific Northwest wet and warmer through mid-January with an active storm track aimed at the Washington and Oregon Coast. This typically means rain instead of snow in Portland as the valley stays on the warm side of weather systems. Perhaps we see a similar weather regime to the end of December.
Here are some model outputs for the next 10 days. Expect to see soggy conditions across the Washington and Oregon coast and an excess amount of rain for the north valley. Also much of eastern Oregon may stay dry, along with the entire state of California!
Expect to continue with warmer than normal temperatures, especially overnight.
I am still not losing hope for citywide snow just yet. The recipe for a lowland snow event is arctic air flooding in from the gorge and a perfectly timed weather system bringing in precipitation. A late-January or February surprise could still be waiting for us.