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Mini Heatwave Will Raise Temperatures This Weekend Before Cooling Again

The recent bout of breezes and cooler temperatures feels like back to normal in the Pacific Northwest with even a few overcast days and sprinkles thrown in.  

But the mercury will rise quickly this weekend, returning the region to above-normal heat for this time of year. Expect clear skies and a spike in temperatures as a ridge of high pressure builds above us, said KPLU weather expert Cliff Mass.

“In fact, by Sunday we’ll get close to 90,” he said.

Friday will warm steadily “into the upper 70s,” Mass said

Then on Saturday, temperatures will climb “certainly to the lower 80s – with clear skies and no precipitation – just a very nice day,”  Mass said.

But, he added, it’s not going to last.

Sunday will be the last day of the warming trend as marine air starts pushing in, first on the coast during the afternoon. Mass says some of that air will reach parts of the inland late Sunday night and into Monday morning.

“Monday should be a definite step down,” Mass said, predicting a drop right back down to the 70s.

Mass said an upper level trough of low pressure will form and bring “much cooler temperatures…clouds and even a chance of a few sprinkles” to the region early next week.

In this week’s podcast, Mass explains why the dynamics of the air on the ocean affect our weather. He describes how a warm patch of water off the coast has been the driving force behind the region's warmest summer ever, because the higher temperatures on the surface of the water heat the air that travels over it.

This has kept nightly low temps several degrees persistently higher than normal.  

"It's been way above normal -- forever," Mass said. "So we start off (each day) much warmer.  It is amazing. (...) The minimum temperatures  are uniformly above normal, day after day after day."

However, Mass said,  the ocean is still cold enough to prevent the arrival of  any tropical storms here, ever.

You can hear the whole conversation by clicking on the “play” icon at the top of this post or downloading the podcast.

The weekly KPLU feature "Weather with Cliff Mass" airs every Friday at 9 a.m. immediately following BirdNote, and twice on Fridayafternoons 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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