One more day of sunshine, then back to Northwest gloom (and mountain snow!) | KNKX

One more day of sunshine, then back to Northwest gloom (and mountain snow!)

Dec 7, 2018

A week of sunny skies that capped nearly a month of unusually clear, bright weather for late fall is wrapping today. KNKX weather expert Cliff Mass says the sun will be a bit filtered as a weather front moves in.

“But the sun will be there and temperatures will go up into the mid-40s," he said Friday morning. "So, really nice day today.”

But, he added, the weekend ahead shows a shift to a much more wet and gloomy pattern, typical for December in the Northwest. “It’s the last day that’ll be completely dry, I think, for a long time,” Mass said.

Along with the clear skies, it has been exceptionally cold this past week – especially in the early morning hours after sunrise, when the radiation from the sun has the weakest effect. Mass noted the frost outside his windows in Seattle on Friday morning.

“Temperatures dropped into the mid- to lower 20s, even in Western Washington," he said. "And so we had ice deposited all over the place. I’m looking outside right now and I can see it.”

WARMER, WETTER WEEKEND

Mass says expect rain to start sometime after midnight going into Saturday morning, as a weak front makes its way across Western Washington.

“Rain will continue into the early morning hours (Saturday) and I think when we wake up tomorrow morning maybe a few sprinkles,” he said Friday. Then there’s a break, making Saturday a decent day for getting outside. “By the time we get to noon on Saturday, the weather systems will be through. We’ll have some partly sunny skies, highs in the mid-40s.”

Then Mass says the weather really starts to change as “serious action comes in” around lunchtime Sunday. 

“A much, much stronger front will come in,” Mass said. “So, Sunday morning may be OK, but then a much stronger front, with rain, a little bit of wind, lots of clouds.”

Along with all the action in the sky, Mass says temperatures will go up a little bit, into the mid- to upper-40s.

RAIN, MOUNTAIN SNOW AHEAD  

Sunday’s strong front is just the first of a series of weather systems that are poised to douse the Northwest all next week in what is a much more typical pattern for this time of year, Mass says. “I’m afraid the high pressure and sunny skies – all the nice stuff – is pretty much over.” 

But he says there’s definitely a bright side to this, for at least one groups of weather-watchers.

“For skiers, it will bring back substantial snow,” Mass said. Snowpack is currently way below normal, at less than 40 percent — a situation that has led to multiple ‘pray for snow’ parties at Snoqualmie Pass. Mass says their prayers will be answered, though they may have to go to Stevens or Baker initially.

“I think there’ll be enough snow during next week to allow skiing to start at several of the higher passes – certainly by next weekend. So, it’s very exciting for the skiers,” Mass said.

To hear the full conversation, including Cliff’s description of how sunny it’s been and how high pressure affects clear skies and fog, you can click on the "play" icon at the top of this post.

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.