Light snow in the lowlands this weekend more likely, but not a certainty

There will be precipitation in the Western Washington lowlands this weekend, but whether or not it is snow is still debatable.

A big ridge of high pressure off the coast is steering weather systems away from the region and shifting inland Thursday.

Rain will come in the lowlands Thursday night into Friday, and snow in the mountains.

Cliff Mass: Parts of Western Washington could see snow next weekend

This system’s associated cold front is expected to swing inland Friday night, with the rain turning to spotty showers Saturday. The cold front’s passage will open the door for colder air to work its way south from the interior of Western Canada.

Question of snow still up in the air

Over the weekend, the question of whether snow could fall in the region’s lowlands arises. Weather guidance at this point offers varying solutions, meaning there is significant uncertainty on exactly what will unfold.

What is known is that the rain Friday will turn to showers Saturday with snow levels dropping to around 400 to 500 feet. Also known is that colder air will begin to blow out of the Fraser River canyon into Whatcom and San Juan counties Saturday night and Sunday. That colder air will likely be enough for those northern areas near the Canadian border to get some snow showers, resulting in spotty light accumulations of perhaps a few inches.

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What is not precisely known is how far south that colder air will work its way west toward the coast and south into the Puget Sound region. At this point, it does look like enough colder air will arrive in these areas to turn spotty rain showers into snow showers with varying light accumulations, particularly in areas of higher elevations and away from the milder waters of Puget Sound. Snow levels will likely be just a few hundred feet above sea level.

High temperatures on Sunday will likely struggle to reach 40 degrees, and Monday remain in the 30s, while lows at night will drop down into the 20s for much of the region. This cold spell is anticipated to linger into the middle of next week, yet available moisture for further showers will be more limited.

Snow forecasts for the complex terrain of Western Washington are always challenging. All the ingredients must come together to help generate lowland snow, including cold enough air blended with available moisture.

This colder weather situation bears watching. More specific forecast details should become more apparent as the weekend draws closer. So monitor the latest forecast information so you can be better prepared.

Ted Buehner is the KIRO Newsradio meteorologist. You can read more of his stories here and follow him on X.