Weather with Cliff Mass
10:02 am
Fri July 18, 2014

On Tap: Cooler, Cloudier Weekend With Chance Of Showers

If you love sunshine, Friday’s the day to get out and enjoy it.

The cooling trend we’ve been experiencing will continue this weekend and even bring some rain with it, says KPLU weather expert Cliff Mass.

“Today (Friday) is the transition day,” Mass said. He expects most morning clouds to burn off and temperatures to get up into the mid- and upper 70s. 

“So not a bad day today. But what you’ll notice is later in the day, it’s going to start clouding up,” Mass said, adding there may even be a few showers overnight and Saturday morning. “So things are going to go downhill a little bit.”

Cloudy With A Good Chance Of Showers Saturday

Expect partly cloudy skies Saturday morning, says Mass, before a stronger system moves in. 

“So there’ll be rain. And the clouds are going to start way up in British Columbia and Northwest Washington, and slowly move down during the day on Saturday,” Mass said.

That means a good chance of showers Saturday, especially later in the day. Mass says clouds will extend all the way to the crest of the Cascades. And it will be cooler, with temperatures only getting up into the low 70s.

Sunday To Be Even Cooler

On Sunday, Mass expects most of the showers will pass through in the morning, but it will get even cooler, with mostly cloudy skies in the afternoon, maybe a few sun breaks and temperatures only reach around 70.

"In some places, it may not even get above the upper 60s. So, definitely a cool down as we go through the weekend with Sunday being the coolest day,” Mass said.

How The Cooling Trend Worsened Wildfires

Ironically, the cooling trend we saw earlier this week made wildfires in eastern Washington worse, but that’s going to ease, says Mass.

“It was the beginning of the cooldown that really helped rev things up,” he said. “Two days ago, when the cooler air started moving in, what that did was set up a difference in pressure across the mountains."

Cooler air coming in the west tends to cause the pressure to rise. Higher pressure on one side tends to increase the winds across the Cascades as the air tries to accelerate from high to low pressure. “And so that actually helped rev up very rapidly the big fire that’s now near Leavenworth,” Mass said.

In any case, Mass says the cool air will be in place over the weekend and temperatures will cool down in eastern Washington.

“They could even get a few sprinkles. So, by the end of this weekend, actually the fire danger will lessen in eastern Washington, as much cooler more humid air moves in,” he said.  

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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.