Snow showers mixed with rain on Thursday and Friday were the final hurrah for the cold that's had the Puget Sound region in its grip since early February. KNKX weather expert Cliff Mass says a sunny weekend is in store, with steadily warming temperatures. He says the threat of lowland snow is over.
“We’re going to have a lot of sun over the weekend,” Mass said, adding that some might even peek through later in the day Friday.
“We have the last band of precipitation moving through the region,” he said Friday morning, adding that it came off the Pacific Ocean and hit mainly from Seattle southward, bringing rain showers right near sea level and snow showers mixed in at higher elevations.
“So this is probably the last snow you’re going to see this season, if you’re in the lowlands,” he said.
Mass says that band of the wet stuff will move through and yield to partly cloudy weather by about 2 p.m. Friday.
"Temperatures will be cold — only in the low 40s,” he said. “So it’ll still be chilly.”
Things start improving over the weekend. Mass expects Saturday to be mainly sunny with temperatures reaching the upper 40s and similar temperatures on Sunday, “maybe a notch warmer, around 50 and partly cloudy,” he said.
“So we’re really going to move up, out of the 30s and low 40s,” he said. “We’re getting closer to normal, which would be in the lower 50s this time of year.”
He says Monday is looking like it will be partly cloudy with temperatures in the upper 40s. And the longer-term forecast is trending toward warmer, more normal temperatures.
ROADS, SOIL WARMING
Mass says if you have any doubt that spring is around the corner, pay attention to the temperatures of our roads and soil. He notes that the main reason the snow that’s fallen this past week has not caused much trouble is that the roads have retained some warmth. That prevents snow from sticking.
“The sun is getting stronger. It is warming the soils, warming the road surfaces,” he said. “Unless you had a huge amount of snow, it was melting off pretty quickly."
And although soil temperatures have been very cold, he says they are starting to warm. Mass says if you check the data for Western Washington, you’ll find many measurements of the temperatures at 8 inches deep registering in the upper 30s.
“That’s pretty cold,” he said. “They’ve just started to warm. Here in Seattle, the soil temperatures are up in the lower 40s. So it’s going to take a while for the soil temperatures to get warm enough for you to think about planting things that depend on warmer temperatures.”
WHY SO COLD?
The lower-than-normal temperatures have dragged on for more than a month all over Washington. Last month was Seattle’s third-coldest February on record and several places in Eastern Washington saw their coldest February ever.
“That — strangely enough — is associated with warmer sea surface temperatures and lots of thunderstorms in parts of the tropical Pacific, right near the dateline” Mass said.
Mass says the thunderstorms put a large amount of energy into the atmosphere, which causes waves to propagate into the mid-latitudes that created the pattern that produced our cold.
Mass says he doesn’t know why the thunderstorms occurred, but computer models show the pattern now dying down.
“And it appears as we get into later this coming week, the temperatures will get up to normal — maybe even slightly above normal," Mass said. "It’s possible by next weekend, we could be in the upper 50s, which will certainly seem warm after what we’ve had.”
WHAT ABOUT EL NIÑO?
Warmer-than-normal temperatures would put us back into conditions that match up with earlier predictions for an El Niño winter, which normally brings a milder and sometimes wetter season to the Pacific Northwest. It correlates with warmer-than-normal sea surface temperatures in the tropical Pacific.
All bets have been off since the pattern weakened in December and January, which were followed by our record-cold February.
“But during the last several weeks, something strange has happened,” Mass said. “It’s revved up. Now we’re back to weak-to-moderate El Niño.” So, it looks like the rest of winter will be an El Niño situation.
“That will torque us towards the warmer side,” Mass said, adding that forecasting skill is never great more than two weeks out. “But it looks like we’re going to break out of this finally.
“The dice are weighted now for us to move to a warmer pattern.”
To hear the full conversation, 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.