When you think of spring, visions of daffodils and cherry blossoms under warm, sunny skies may come to mind. Turns out the more typical aspects of this season, meteorologically speaking, come from the unstable atmosphere, which produces lots of wet and showery, cool weather.
Spring is the most unstable time of the year, says KNKX weather expert Cliff Mass. And the forecast for the next few days comes from that pattern. Cool, wet and showery skies will dominate on Friday and much of the weekend.
“We have very cold air coming in aloft,” said Mass, who teaches atmospheric sciences at the University of Washington in Seattle.
And the cold air is generating a lot of convection.
“Big cumulous clouds, even a few thunderstorms that are producing intermittent heavy showers with a little bit of gaps in between. So, it’s going to be showery,” Mass said. And temperatures will only get into the mid-40s.
“Cooler than normal,” he said. “You may even see a little bit of small hail or graupel – these little pellets—coming out of the sky. So don’t be surprised…. bring an umbrella,” he said.
Mass says this typical spring pattern will continue on Saturday and Sunday.
“We’re still going to have some of that cold, unstable air. So I expect showers. It won’t be quite as much,” as Friday, he said.
And temperatures will be a bit warmer, likely around 50.
Mass says Sunday will be the best day of the weekend for getting outside, especially in the morning.
“Maybe 30 percent chance of showers in any location, maybe a few sun breaks,” Mass said. “But there will be some showers floating around, particularly in the mountains. So that’s what’s we have to look forward to.”
Easing Up For The Workweek
Mass says on Monday and Tuesday, the rainy weather starts to taper off a bit.
“Some weak fronts are coming in so a little bit of clouds and showers, temperatures around 50,” he said.
And then a ridge of high pressure builds in mid-week, pushing out most of the wet stuff.
“So I expect the big dry period to be Wednesday and Thursday,” Mass said.
But the dominant pattern for the week is for cooler temps and rain on and off.
“It’s not atypical this time of the year, but it’s definitely going to be showery,” he said.
To hear the full conversation – including an explanation of why spring is the most unstable time of year and why this year's start to spring is expected to be cooler than normal – 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.