“No one’s going to mistake this weekend for July,” quipped KPLU weather expert Cliff Mass. He says Saturday will be the best day of a mostly cloudy weekend that will become increasingly wet.
Friday, Mass says there will be some showers floating around, mostly offshore, and clouds elsewhere. “For most people, it’ll be relatively dry – much drier than yesterday,” He said. “So, you know, an okay day.” Temperatures will get into the upper 60s.
Get Your Outdoor Fun In On Saturday
Mass says Saturday will be the transitional day. There will be some clouds in the morning, he says. “But I think we’ll have some long periods with no rain,” He predicts the biggest potential for rain will be along the coast and the northern part of the state. “So you go south and you’ll probably be dry most of the day, but there will be some clouds,” he said. Overall it will be a partly cloudy day, with highs reaching 70 or maybe the low 70s. “So it’ll be the best day of the weekend,” Mass said.
Sunday: A Front Moves In
He says on Sunday, a very strong front will be coming in later in the day. “So, in the morning you could probably eke something out – your run or some other fun thing outdoors,” Mass advised. He says that front will be coming in during the afternoon and evening, bringing substantial rain with it. “So definitely, the end of the day will be wet,” he said.
Next Week: Improving
But as that front goes through, Mass says high pressure will build behind it. “So it looks better on Monday and Tuesday,” Mass said, predicting partly cloudy skies and a high of around 70 early next week.
As Precipitation Season Begins, Know Your Radar
As the rainiest time of year kicks off, Mass wants to educate people about what they’re actually seeing when colorful radar images predict the weather.
“It’s very important to know what’s on those radar screens that are shown on TV and on the web and on your favorite app,” Mass said.
He says the radar beams are best at telling you where there is heavier precipitation and the rate at which it is falling.
“But it’s not precipitation at one level, the radar beam is sloped up,” Mass said, “so you’re seeing this sloping radar beam’s view of where it’s precipitating.”
So it has limits and will pick up some areas better than others. Mass also cautions that radar doesn’t see clouds, because the water droplets that make up the cloud are too small. And its capture of drizzle is sporadic at best. Radar signals also get blocked by mountain ranges, which is a big issue in the Northwest.
But radar can pick up other phenomena, such as migrating birds and smoke from wildfires. Overall he thinks we need more radar equipment.
“There’s a lot of places we still can’t see,” says Mass. “For instance there’s almost no radar coverage along the Oregon coast. Basically, South of around Newport, the radar coverage is nil,” he said. The eastern slopes of the Cascades are another blind spot.
“This is a real problem. We can’t see heavy thunderstorms in places like Wenatchee or Yakima,” Mass said. And that means fire detection is also missing there. “Fires are observable on radar and we don’t have radars that see it in those crucial spots,” he said.
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.
