Another Bout of Weekend Showers, Then Sunny And Clear As Fall Begins | KNKX

Another Bout of Weekend Showers, Then Sunny And Clear As Fall Begins

Sep 21, 2018

Friday is officially the final day of summer, marked by the fall equinox. Showery weather is ushering in the transition in western Washington, though it’s expected to make way for some glorious conditions next week.

Rain Starts Friday Night

KNKX weather expert Cliff Mass said Friday would not be too bad during the day.

“A weather system’s approaching. We’ll have increasing clouds, but I think the rain’s going to hold off until this evening,” he said.

But he said a front will be moving in overnight, and that means a more or less guaranteed prediction of rain Friday night.

“Expect the pattering outside sometime probably after nine o’clock,” Mass said.

On Saturday, he says expect “considerable cloudiness” and “plenty of showers, particularly on the western slopes of the Cascades.”

Also, in areas of northern Puget Sound, what’s known as a Puget Sound Convergence Zone will form. That’s when northwest winds coming off the Pacific Ocean are split by the Olympic mountains and then converge on the other side, causing convection that leads to a narrow band of rain showers.

“So, somewhere between Seattle and Everett a line of showers will develop,” Mass said. But there will also be areas that stay dry.

“So, cloudy, some rain, but you might be able to keep out of it if you keep away from certain places,” he said.

Clouds Burning Off Sunday

Mass says Sunday will be the day of big improvement, with clouds in the morning that will burn off later on.

“And as we get later into Sunday, a ridge of high pressure is going to start building in,” he said. “So Sunday, expect temperatures getting up to around 70.”

Clear Blue Skies Next Week

If that sounds almost like a return to summer, just wait. Mass says next week it gets even better, when an extraordinary ridge high pressure develops in the eastern Pacific.

“I think we’re going to be completely dry for the entire week. And temperatures will get up to around 70 – even low 70s a few days,” he said. “It’s going to be the most perfect fall weather you can possibly imagine.”

So if the showery weather gets you down, hang in there. We’ve got a week of glory coming up, once we get through the weekend.

To hear the full conversation, including Cliff’s discussion of why we don’t have hurricanes in the Northwest and of the controversy surrounding the category system for hurricanes, you can click on the 'play' icon at the top of this post.

Weather with Cliff Mass airs at 9:02 a.m. Friday, right after 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 podcasts of Weather with Cliff Mass shows, via iTunes or Google Play