Overnight rainfall gives way to Seafair weekend sunshine. And what’s with those UFO clouds? | KNKX

Overnight rainfall gives way to Seafair weekend sunshine. And what’s with those UFO clouds?

Aug 2, 2019

August was off to a warm and sunny start Thursday, with blue skies and nearly perfect summer weather.

But people in the Puget Sound region woke up to as much as a half an inch of rain that fell overnight; on the coast, the precipitation totaled as much as an inch and a half. Temperatures dropped quite a bit, too.

KNKX weather expert Cliff Mass said a strong front came through and brought along an intense band of showers.

“It was pretty strong,” he said.

But he expected it to move through and be done by midday, leaving behind just a possibility of residual showers, along with sun breaks and temperatures getting back up into the 70s.

SUNNY, WARM SEAFAIR

“As we get into the weekend, temperatures will progressively warm,” said Mass, who predicts low 80s on Saturday with plenty of sun. "A really nice day."

On Sunday, expect mid- to upper-80s. “Sunday will actually be warm — so that’s good for Seafair weekend,” Mass said.

And Mass expects that warmth to stick around for the start of next week. “It looks like Monday and Tuesday — particularly Monday — can be warm,” he said.  

But then, he says, forecast models are projecting the return of more cool, wet weather.

“The upper level troughs (of low pressure) that have been affecting us and giving us clouds and precipitation will come back later in the week,” Mass said. “So there could be more clouds and rain as we get into Thursday and Friday.”

LOW SMOKE RISK

Mass notes the mix of rainy and more temperate weather is lessening the potential for wildfires, especially to the north in British Columbia. B.C. was the main source of smoke that caused major air quality issues last summer, making Seattle’s air quality as bad or worse than Beijing’s at times. Mass says he does not expect a repeat of that this summer.

“There could be a few small fires, but it’s just too wet up there," Mass said, adding that smoke from British Columbia wafted into Seattle and Washington’s skies for more than half of last summer. “That just isn’t going to happen."  

LENTICULAR CLOUDS

Mass says if you want to know when one of the storms that helps lessen fire risk is coming in, there’s a particular kind of cloud that can be a signal. He says look for lenticular clouds. He saw several Thursday night before the big rains came. 

“Look up in the sky and before some of these storm systems come in, you (can) see these lense-shaped, lenticular clouds,” Mass said. “Some people think they look like UFOs.”

In fact there’s a history that dates back to the 1940s of lenticular clouds being mistaken for UFOs. This likely happens because they sometimes move very quickly through the sky, along with the changing weather systems.

Mass says he admires them more for their aesthetic qualities. They form near mountains and come from wave patterns in the atmosphere that can create luminiscent colors. But along with that, they're useful, as sentinels for when a storm is on its way.

“They’re not only extremely beautiful, but they also are signs of what’s going to happen, when a weather system is approaching from off the coast,” Mass said.

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.