Rain Returning And 'Mixed Bag' For Mother’s Day Forecast In the Northwest

May 12, 2017

Any sunshine seen early Friday was probably just a tantalizing taste of what won’t be the pattern for at least a week here in the Pacific Northwest, says KNKX weather expert Cliff Mass.

“We have a series of showers that are coming through [Friday morning],” said Mass who teaches atmospheric sciences at the University of Washington.

He says the alternation between showers and so-called “sunbreaks” is “very, very typical,” especially after a stormy front passes through, as one did on Thursday in and around Seattle.

“And we have this cold air getting over warm water and the thing starts percolating up. And so we have showery regime,” Mass said. He expects that to be roughly the same story for most of the weekend.

“There’ll be breaks and there’ll be rain, [with]  temperatures getting up into the mid- to upper 50s for most people.”

Then, later on Saturday, Mass expects an upper-level trough to come through.

“That causes lift and clouds. And so, we will see showers increasing Saturday night, into Sunday morning. So, there’ll definitely be some rain from that,” he said.

This means the same mix of showers, rain and sun breaks on Sunday – which is Mother’s Day.

No Guarantee Of Sun On Mother's Day

Mass said there is a “good chance” that the typical stormy spring weather known as a “Puget Sound Convergence Zone” will set up north of Seattle. That zone is where air masses come together after a jet stream from the Pacific Ocean is split by the Olympic Mountain range. As the two sides of that system collide, it produces a lot of precipitation.

Mass says for most people in the region, that will rain on Mother’s Day .

“So, again, another mediocre day, temperatures below normal, maybe 56 or 55,” he said.

That’s the nicer part of the forecast, at least for now.  Mass says later on Monday into Tuesday morning, a strong system of low pressure will come in, bringing a lot more rain with it early next week.

But Mass says there is a light at the end of that tunnel. By Wednesday of next week he expects everything will have changed pretty dramatically.

“There’s a major change in weather regime. High pressure will build over the eastern Pacific. And believe it or not, I think it’s going to be in place for at least a week. So, starting later on Tuesday, going into the weekend, I expect us to warm up, dry out, with absolutely beautiful conditions. So, really something to look forward to,” he said.

To hear the full discussion of the weekend weather along with an explanation of why a lot of flooding is happening right now on rivers in Washington state, 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 podcasts of ‘Weather with Cliff Mass’ shows, via iTunes or Google Play.