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Is this extreme heat a sign of things to come for the Northwest?

It's going to be hot this weekend. (AP file)

The Pacific Northwest is in the midst of hot weather that’s expected to break several heat records.

But why now? Some Junes we name “Junuary” or “June Gloom,” and we might tell the California transplants that summer doesn’t really start until July 5th. Cliff Mass, University of Washington Professor of Atmospheric Sciences, tells the Dori Monson Show that this weather event is a result of a combination of extraordinary factors.

“First we have this gigantic ridge of high pressure and warm air over us and that’s due to something that’s happened over the Pacific — there’s like a wave pattern that’s amplified. That gave us this super warm ridge. Then, on top of that, we have this trough of low pressure coming in. … The combination will cause a very strong downslope, easterly flow on the western slopes of the Cascades. So air is going to be sinking down on the western slopes of the Cascades and as the air sinks, it gets compressed and warm.”

Seattle, counties open cooling centers, pools to help with weekend heat

“That’s why this doesn’t happen very often,” Mass said. “You need all these moving pieces at the same time.”

But is the heat we’re experiencing a result of global warming?

“Global warming is making a small contribution, but it’s a small one,” Mass explained. “We’ve warmed up 1-2 degrees Fahrenheit in the last 50 years or so and some of that is due to us, probably.”

But Mass says we’re going to be 30-40 degrees above normal in some places this weekend. Maybe 1-2 degrees is due to global warming, but another 35 is natural, he says. Global warming is a small contributor, but Mass says it’s not a key factor in this weekend’s heat wave.

He doesn’t believe that this extreme heat is predictive in any way. You can always count on things drying out and getting warmer this time of year, typical of most Northwest summers.

“I don’t foresee that this is telling us that we’re going to see more absolute extremes like this,” Mass said.

What about dry heat? 107 is nothing in Palm Springs or Las Vegas, but that’s a dry heat. Does dry heat really make high temperatures feel more bearable?

Besides just not being used to it, Mass said there’s also air conditioning almost everywhere you go in the desert.

“The air will be moister for us. The Dew Point, which is the measurement for how much moisture is in the air, is going to be in the 60s,” Mass explained. “That makes evaporation less effective for cooling off. Moisture will be higher here, which will make it a little bit worse than a super dry heat in places like Palm Springs or Las Vegas.”

According to, Las Vegas is expected to see temperatures range from 107-109 through Monday. In Palm Springs, temperatures will range from 113-117. But it’s a dry heat.

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