A push of marine air from the cold Pacific Ocean that came in Thursday night is bringing morning clouds to the greater Puget Sound region. These low clouds typically burn off by noon, though they can stick around longer.
KNKX weather expert Cliff Mass expects Friday and Saturday to provide sunny afternoons, with the clouds opening up to blue skies and temperatures in the mid- to upper-70s.
He says on Sunday, it will take longer for the sun to push through the clouds.
“I think they’ll thicken up on Sunday,” Mass said. “There could even be some sprinkles, along the coast particularly and maybe on the western slopes of the Cascades. But eventually they’ll burn off, in the late afternoon.”
Mass says that warmth will continue through midweek, with even warmer temperatures on Tuesday and Wednesday, followed by the possibility of heavier showers on Wednesday and Thursday. That’s due to a big shift in the circulation that’s showing up in the forecast models, which show the jet stream strengthening and heading toward the Northwest in what Mass says would be the first Pacific front of the season.
“But, it’s a little early to be sure about that now,” he added.
One thing he says is fairly certain in summertime is the prevalence of certain wind patterns – both summer breezes and stronger winds that generally rev up in the later afternoons and evenings.
‘NATURAL AIR CONDITIONING’
Mass says summer days that reach the mid-80s and 90s in the greater Seattle area come with a form of "natural air conditioning" called the Sound Breeze. It consistently develops in the afternoons with winds coming from the north and reaching speeds of up to about 10-12 mph.
“In fact I’ve done papers on the subject. And what happens is we have a gigantic sea breeze here in Western Washington,” Mass said. “We have natural air conditioning here in Puget Sound.”
It forms because all of the land masses of Puget Sound – which actually are greater than the water areas – heat up during the day. And the heat from that mixes with the cooling influence of the water out toward the Pacific Ocean and in the Strait of Juan de Fuca.
“And so the air pushes through the Strait of Juan de Fuca and down into Puget Sound,” Mass said.
He says look for the wind blowing across the water in the afternoons: “That’s the Sound Breeze. And that can really cool you off if you get to the right locations.”
Mass has a new blog post about the best places he has found in the greater Seattle area. His favorite is Kite Hill, in Magnuson Park near Lake Washington. Discovery Park, Carkeek Park, Richmond Beach and Alki Point also are on his list.
“So some of the exposed parks – especially along the water – can really get this nice Sound Breeze type wind during the late afternoon and early evening," he said. "It generally dies around 9 or 10 o'clock. But if you get out there early, you can really enjoy it.”
STRONGER SUMMER WINDS
Local sailors and energy planners are likely aware of another kind of summer wind that consistently shows up in the region. Both the eastern side of the Strait of Juan de Fuca and the eastern slopes of the Cascades feel the punch of much stronger blowing that shows up almost like clockwork.
“If you want strong winds, almost every single day of the week during the summer, just go to the strait of Juan de Fuca,” Mass said. “In fact, on many summer nights, they have small craft warnings going on.”
Mass says this is connected with the Sound Breeze. It’s the same dynamic of warmer land masses and cooler ocean that accelerates and creates the strong afternoon gusts out in the strait, on the eastern side.
“And you can get winds of 25-30 miles per hour in some places,” Mass said. “So, get to Port Townsend or Whidbey Island, north Whidbey island – they can get hit. That whole region gets very strong winds during the afternoon and early evening that can really be substantial.”
About 150 miles away to the east as the crow flies, you can see more evidence of these strong winds in the form of huge white turbines across the eastern slopes of the Cascades.
Mass says as that same cool air reaches the mountains, it accelerates once it spills over and heads downward. Here too, the winds regularly reach 20-30 mph in the late afternoon and evening, explaining the prevalence of wind farms around places such as Ellensburg, Vantage and Thorp.
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.