First lowland snow threat of winter arrives in western WA

For the first time this winter season, there is a threat of lowland snow this week, though the odds are quite low. The last time Seattle-Tacoma International Airport (SEA) had no snow during the winter was back in 1991-92, an El Niño winter season.

More recently, only trace amounts of snow were reported during the winters of 2009-10 and 2015-16.

Much cooler weather pattern

A cool unstable air mass associated with an upper-level low is forecast to settle in off the coast Monday. This weather system will bring showers to western Washington through Wednesday, when the upper low is expected to ease onshore. Another cool upper-level low-pressure system will follow off the coast later in the week.

The cool air mass will drop snow levels to around 1,000 feet Monday across much of Western Washington, and to around 500 feet the rest of the workweek. The unsettled conditions will produce “hit and miss” showers. The threat of any accumulating snow in the lowlands should be limited to the overnight and morning hours when temperatures reach their daily lows.

The best chance for any accumulating snow in lower elevations will likely be along the coastal region from north of Hoquiam to the western half of the Strait of Juan de Fuca. Inland, higher hills and even a few lower elevations could see some snow on grassy surfaces and rooftops.

Western Washington temperatures this week will be unseasonably cool. The average high temperature is around 50 degrees. Highs this week will struggle to reach the lower to mid-40s, while low temperatures are forecast in the lower to mid-30s, making icy spots on roadways a distinct possibility.

Overall, this week, given the spotty character of the expected showers, precipitation amounts will be rather light. For the lowlands from Monday through Friday, total amounts will quite likely be less than one inch. In the mountains, where adding to the meager snowpack is needed to fall in feet, snow amounts will likely fall in the 10-20 inches of new snow range.

Latest mountain snowpack status

Over the weekend, the Northwest Avalanche Center updated its snow depth report for the Olympics and Cascades, revealing that the mountain snowpack was still struggling. Snowfall over the weekend was quite welcome, though relatively light, with two to six inches of new snow at Hurricane Ridge in the Olympics and from Stevens Pass southward. The exception was Mt. Baker, which received 15 inches of fresh snow over the weekend.

The Avalanche Center report also noted that the overall mountain snowpack ranged from about 35-47% of average for mid-February. Mt. Baker came in at 61% of average.

Wanted: More mountain snow

The latest weather outlook, which extends through the first of March, offers some promise for a recovering mountain snowpack. The outlook reflects good odds on near-average temperatures and wetter-than-average conditions for Western Washington. These conditions should translate to more snow in the mountains.

This week is likely the best chance for any snowfall in the lowlands of Western Washington this winter season. For SEA, will the results be no snow, just a trace, or will it receive a tenth to two inches of snow?  Oh, the drama!

Ted Buehner is the KIRO Newsradio meteorologist. Follow him on X and Bluesky. Read more of his stories here.