Why Spring Is Rainbow Season Here In Cascadia

Apr 21, 2017

If you’ve been feeling like you can’t stand the rain lately, get outside on Friday. Rain is coming in on Saturday afternoon and it only gets wetter from there.  

KNKX weather expert Cliff Mass is expecting “the mother of all atmospheric rivers” to hit southern Washington and Oregon pretty hard early next week. 

Wet This Weekend  

Wet, but not too cold, Mass said of the weekend ahead. So you can get out there if you like puddle jumping or pulling weeds in the rain. If sun’s your thing, enjoy Friday.

“The best day of all” Mass says of Friday. It will be sunny and clear, with temps reaching nearly 60 degrees.  

“Nothing close to it the rest of the weekend,” Mass said.

Saturday Morning: Cloudy And Dry, But Forecast Only Gets Wetter After That

A major weather system will be coming in during the afternoon on Saturday, Mass said.  So, while Saturday morning may start off dry, he expects it to start raining by midday.

“It will be cloudy, but it will be dry,” he said.  “By lunchtime, that system will come barreling in to Western Washington and I expect precipitation over the whole afternoon.”

So it will not be great.  And temperatures will drop down to the mid-50s, so definitely a decline.”

And on Sunday, Mass says another weather system comes in, so during the afternoon, a strong front will bring more rain.

For hiking or any other outdoor pursuits that you prefer to do dry, “it doesn’t look good,” Mass said.

“Western Washington’s going to have rain on and off pretty much the whole weekend. And temperatures dropping back into the lower to mid-50s.”

‘A Very Wet April’ 

Mass says another series of weather disturbances is coming in on Monday and Tuesday.

At that time, expect “the mother of all atmospheric rivers,” meaning the atmospheric current that brings us lots of moisture and warm temperatures from the tropics, producing. It will produce lots of rain and it will be aimed right at Oregon and Southern Washington Mass says.

“Several inches in the lowlands and more in the mountains” he says. “So this is turning out to be a very wet April,” he said. “I don’t know if it will be the wettest April on record, but we’re already way above normal.”

On The Upside: Rainbows!

‘This is rainbow season,” Mass confirms. That’s because the sun is at the right position in the sky for it. “The angles are good … We’re into this shower and sunbreak regime,” Mass said.

“That’s classic for spring,” he says. It the time of year when there are heavy showers and the sun gets between them. “It gets onto the rain and produces the rainbows.”

“And I’ve seen a few myself,” he says “including a double rainbow the other night.”

To hear the podcast of this segment, including a discussion of Mass’s exploration of why his grass seeds are not sprouting right now, even though it’s late in the season 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.