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Washington’s ‘Heat Storm’ Subsiding, But More Unusually Warm Weather This Weekend

Tim Durkan Photography
A Seattle sunset with evidence of the heat storm behind the Olympic Mountains on Thursday April 7, 2016.

Western Washington’s unseasonably high temperatures will be subsiding, but KPLU weather expert Cliff Mass says you may want to keep the shorts and sunglasses handy.

“I’d keep them around,” Mass said, though he added that many people will be needing them less over the weekend. He said Friday will still be very warm and sunny.

Another Hot Day Friday – Except On The Coast

“Maybe not quite as warm as yesterday, in some places,” he said, but the air above us is still “warmer than we generally see till the middle of summer.”

Expect “sun and really nice conditions.”

Mass says temperatures will probably spike as high as the low 80s in Eastern Washington and reach into the upper 70s or even as high as 80 in the Seattle area. That would be a slight decrease from Thursday’s temps, which broke records at many locations around the state. He says recordings made by equipment on the National Weather Service’s weather balloon at Quillayute Airport were what struck him the most.

“The temperature at about 5,000 feet [Friday] morning was the warmest ever observed for any day between January 1st and April 24th,” Mass said. “It is an all-time warm temperature record – that is pretty amazing stuff.”

The place that will remain a little cooler, Mass says, is the coast, where marine air has already pushed in to the Strait of Juan de Fuca. ”So they’ll be much, much cooler” on Friday and Saturday.

Cooler Weekend Days With Morning Clouds, Sunny Afternoons

Mass says onshore flow will push some low clouds inland, probably in the morning hours on Saturday and Sunday.

“But that will burn off, so I expect temperatures to drop back to roughly the upper 60s – maybe around 70 on Saturday, mid-60s on Sunday.”

He says rain will stay away till Monday at least.  “No precipitation at all — so, a cool down, but still above normal.” 

Then, next week, Mass says it looks like there will be few weak weather systems coming through, bringing back more typical April showers.

“So we should have some showers mid-week, but nothing serious.”

Heat Storm - Not A Heat Wave

What caused Thursday’s spike in temperatures? Mass says it was a combination of the unusually warm temperatures aloft with high pressure over eastern Washington locking in the warmth, while low pressure in the western lowlands kept easterly [or offshore] flow pushing in toward the Cascade Mountains.  

“And when that air descended on the western slopes of the Cascades ... [and] the Olympics, the air was compressed and warmed further.”

That’s why the highest temperatures observed were in places near the foothills, such as North Bend, Black Diamond or Enumclaw – and even Lake Quinault, southwest of the Olympics.

“We’re talking about temperatures getting up into the upper 80s,” Mass said.

But Mass says because the forces at work are more of a pulse than a sustained trend, the correct description is to call this a “heat storm,” not a “heat wave.” 

He says heat waves are when the above normal temperatures stick around for several days.

And Don’t Call This Global Warming

Mass adds that lots of people like to say this is global warming. But he says the majority of the heat we’ve been experiencing is not due to climate change caused by greenhouse gas emissions.

“The reason we’re so warm was because of this high pressure, the warm temperatures associated with it and the offshore flow,” Mass said.  So, is global warming contributing to it? I’m sure it is, perhaps maybe one or two degrees of this was global warming,” he says. “But you have to consider that this was an anomaly, a difference from normal of like 25 degrees. And there’s no way that global warming could have done most of this.”

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.

Bellamy Pailthorp covers the environment beat for KNKX, where she has worked since 1999. From 2000-2012, she covered the business and labor beat. Bellamy has a deep interest in Indigenous affairs and the Salish Sea. She has a masters in journalism from Columbia University.
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