The week before Thanksgiving is normally the wettest, stormiest part of the year in the Pacific Northwest. And true to form, the rains and wet clouds are back, says KPLU weather expert Cliff Mass.
“If you look at the records going back decades, this is the week: ground zero for storms and wetness here in the Northwest. And it may not disappoint,” Mass said.
Mass says the big ridge that has been locking in remarkably clear, dry skies over the West Coast has now moved off and dissipated.
“After a period where we’ve had a lot of ridging, cold air — it’s been really pretty dull the last several weeks, everything is changing,” he said.
The jet stream that runs along the West Coast and produces most of our storms is strengthening, and it’s aimed right at us.
“It’s going to be coming in right in to the Northwest, right off that Pacific during this week, and we are going to see a progression of storms come through,” Mass said. “In addition, the temperatures aloft will cool, because the jet stream is just south of us and that will allow a substantial amount of snow to fall in the mountains, particularly above 3,500 or 4,000 feet."
Friday: Rain And Wind
Friday will be "rainy the whole day,” Mass said, bringing in maybe a half an inch in the lowlands and as much as a few inches in the mountains.
After that front moves through Friday night, Mass says, we'll see more wind. He says it will be blustery around Seattle, but on northern Whidbey Island and in the San Juans, expect winds that could gust to 30 to 50 mph.
“It’s going to be very windy there and also very windy on the coast, so people should watch out for that,” Mass said.
Saturday: More Winds, Cooler Temps And ‘Substantial’ Mountain Snow
On Saturday, Mass says the winds will switch to west aloft and the air will cool down.
“And we can see substantial snow in the mountains. Particularly above 3,500 feet or so, there could be a foot or two of snow, especially above 4,000 feet, Mass said. “So the mountains are going to start accumulating snow — and they need it, it’s way down right now.”
It will be raining in the lowlands, but not as hard.
“We’ll have a lot of showers, post-frontal showers, some sprinkles on and off down in Seattle,“ Mass said, with heavier precipitation in the mountains and along the coast.
Sunday: Steady Rain, More Mountain Snow
Mass says another stormy system will come in late Saturday night or Sunday morning, bringing steady rain with it. That will move through mid-day on Sunday, but there will be a lot of showers behind it.
“And more snow in the mountains,” Mass said. “So, this is going to be a very wet period over the weekend, with a few breaks.”
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The weekly KPLU 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 KPLU 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.
