Seattle area’s first taste of winter snow could arrive next week as temperatures plunge

Forecasts call for heavy snow at Snoqualmie Pass this weekend, with light accumulations also possible in the Seattle area starting next Tuesday.

Most of the area at the pass will be dry to start Saturday with a little bit of sun. High clouds move in pretty quickly ahead of a stronger weather system.

This will bring increasing rain and mountain snow from Saturday evening through the day on Sunday, only tapering off on Sunday evening. Expect very poor pass travel, and folks headed to the Apple Cup should be aware that getting back from Pullman on Saturday night or all day Sunday could be very difficult indeed.

Pullman has not hosted the rivalry game since 2018. Therefore, WSDOT anticipates pre-pandemic traffic levels on US-26.

KIRO 7′s Lauren Donovan spoke to a number of football fans who say the looming forecast, motivated them to hit the road Friday afternoon instead of Saturday morning.

“We were thinking because it’s such a late game, maybe we’ll go tomorrow,” said WSU student Emma Robins. “But, you can never really predict what the pass is going to do.”

>> Download the KIRO 7 Weather App to track the mountain storm

Expect 8 to 18 inches of snowfall in the passes from Saturday night through Sunday night with isolated higher totals. In the lowlands, more than a half-inch of rain will fall and breezes could top 30 mph on Sunday. A Winter Storm Warning has been issued for this threat. It will be in effect from 7 p.m. Saturday through 10 a.m. Monday, in areas about 1,500 feet.

Colder air arrives on Sunday evening as precipitation comes to an end, but snow levels will fall below 1,000 feet, meaning we could have some foothills or higher hills snowflakes into Sunday night and early Monday morning. I don’t expect any significant difficulty with travel in the lowlands heading into Monday morning, however.

Monday itself will be mainly dry with some sun and highs in the 40s. It now looks like we get through most of Tuesday without precipitation but temperatures will be quite chilly with lows below freezing and highs Tuesday near 40.

Chance of lowland snow

Precipitation looks to arrive Tuesday night through Wednesday with a trough of low pressure aloft falling south out of western British Columbia. Just how much moisture is available with this system is unclear but it will be cold enough for some lowland snow, particularly above about 200 to 300 feet elevation from Tuesday night through early Thursday.

>> KIRO 7 PinPoint 7-Day Forecast

We’ll be updating that forecast as we get closer, but some light accumulations during this time frame in lowland locations appear likely, particularly above 200-300 feet elevation.

There are signs of even colder air plunging into the region around next Thursday and Friday, possibly lasting several days. If this pans out — and it is not a certainty — high temperatures may barely get above freezing some days with nights well below freezing.

It will be something to keep an eye out for as it would be the coldest air of the season so far — if it occurs. If it does get that cold, however, it could well be too dry for precipitation.

Expect high temperatures in the 30s and lows in the 20s to end next week.