Plenty of rain and lots of snow in the mountains could complicate holiday travel plans this Thanksgiving weekend. Pack your patience, especially if you are hitting local roads on Thursday, says knkx weather expert Cliff Mass.
He said Wednesday was providing a bit of a break after a strong front went through Tuesday night, producing very wet and treacherous conditions on local roads.
“Accidents everywhere,” Mass said. “But today we just have a few showers behind the front,” he said of Wednesday. “There’ll be some snow showers in the Cascades, probably above 3,000–3,500 feet, but actually, today’s not a bad day,” he said. “The big storm will be tomorrow.”
Mass says a strong front will come through during the morning hours of Thanksgiving.
“So it’ll be raining pretty hard. And that front will move through during the early afternoon hours, but behind that there’ll be lots of showers and cooling temperatures.”
He says that means snow will start developing in the Cascades during the day on Thanksgiving, with the snow level descending “probably to around 3,500-3,000 feet by the end of the day.”
With Snoqualmie Pass at 3,022 feet and Stevens at 4,062, crossing to the other side of the state could become treacherous.
“The passes are something of great concern,” Mass said, with lots of snow expected. “I think there’ll be at least two to six inches before tomorrow is up,” Mass said. But he added that it looks like most of it will come later in the day.
“So if you get across the mountains I think at least before 2 or 3 o'clock, you’ll probably miss most of the snow, which will happen later in the day,” he said.
Windy Thursday Night
Mass says a weak disturbance will develop off the Oregon coast and move northward through the Puget Sound region later on Thanksgiving, likely causing winds to pick up toward the end of the day.
“So you might see winds gusting to 15-25 miles per hour here in Seattle, maybe more in Northwest Washington,” Mass said.
He says the winds could gust to 25-35 miles per hour in those areas.
“So, if you’re up by Bellingham or the San Juans, it could get gusty later on Thanksgiving Day,” he said.
Mass says things calm down and Friday will provide a bit of a break.
“There’ll be some weak disturbances coming through, some showers and sun breaks here in Seattle, but there’ll be snow showers in the mountains,” he said. Once again, he says the snow level will be around 3,000-3,500 feet. But he says he doesn’t expect huge amounts of the white stuff.
“The key issue here is the temperatures are kind of on the edge for snow. It’ll be cold enough, but not that cold. And so I don’t expect a real big snow dump in Snoqualmie Pass,” Mass said.
“Stevens will have a little bit more and if you get up above 4,500 feet, then you get a lot of snow,” he said.
Mass says expect less precipitation as we get into the weekend.
“We’re going to actually start drying out. There’s a few weak disturbances that’ll move through on Saturday, but I don’t expect a lot over the weekend, especially Sunday. Sunday right now looks like the best day of the weekend,” he said.
Mass says a ridge develops over the eastern Pacific on Monday and Tuesday, which should keep the precipitation to a minimum as people get back to work.
“So it’ll be generally dry except for a few snow showers up in the mountains and a few sprinkles down here,” he said.
“So the main action is going to be Thursday here in the lowlands and then you can expect some residual snow in the mountains, but not a huge amount later in the weekend,” Mass said.
To hear the forecast along with Cliff’s description of the conditions needed to get abundant snow in the Cascade Mountains, you can click on the “play” icon at the top of this post.
The weekly knkx feature 'Weather with Cliff Mass’ airs every Friday at 9 a.m. immediately following ‘BirdNote’, and twice on Friday afternoons during ‘All Things Considered’. The feature is hosted by knkx environment reporter Bellamy Pailthorp. Cliff Mass is a University of Washington professor of atmospheric sciences, a renowned Seattle weather prognosticator, and a popular weather blogger. You can also subscribe to a podcast of ‘Weather with Cliff Mass’ shows.