Local rain — and California’s record showers — mean healthy water supplies, delayed fire season | KNKX

Local rain — and California’s record showers — mean healthy water supplies, delayed fire season

May 17, 2019

The wet season has returned to Western Washington, with showers and all out rain alternating through early next week, a continuation of the pattern we’ve been seeing for a while.

“But none of that’s going to be that heavy. And the reason is, most of the weather is going into California,” said KNKX weather expert Cliff Mass, who teaches atmospheric sciences at the University of Washington.

Mass says Saturday will be the best day of the weekend, with partly cloudy skies, just a few showers in the morning and temperatures reaching near 70 degrees.

Sunday, he says, there will be light rain, especially from the morning into the afternoon hours as a weak frontal system moves in from Oregon. And temperatures will only reach the mid-60s at the highest.

Next week, Mass says multiple weather systems are expected on Monday and Tuesday, bringing back more rain.

But this is nothing compared to the rain California is experiencing: the wettest second half of May on record, with 2 inches of rain in places such as San Francisco, 6-9 inches in the coastal mountains and even several feet of snow piling up in the high Sierra mountains.

Mass says California's weather and ours are connected.

“We have an extraordinarily unusual weather situation," he said. "Normally, as you get into mid- to late-May, the jet stream is moving north into Alaska and we might get a few showers, but California is normally dry – virtually entirely dry.

“But what’s happened is we’ve had this trough (of low pressure) along the West Coast that has sent the jet stream down into Central and Southern California. And the weather systems, which are invigorated with this, are moving in south of us.”

So, the light precipitation hitting Western Washington now is the northern edge of these storms, as weak frontal bands go through.

“But in California, they’re getting the primo stuff. And the amounts they’re getting are jaw dropping,” Mass said. “We’re seeing absolutely record-breaking precipitation down there in California – and looking at the latest (computer forecast) models, it’s not going away.”

Mass says drought is no longer a concern in California. Reservoirs are full, soils are moist and stream levels are above normal.

“So drought is over there in California," he said. "The only issue they have is their ground water is less than normal because they’ve mined it for the last several decades. That’ll take a while to adjust. But in terms of how much water they have available, it’s huge. They’re in very good shape.”

Mass says Washington’s outlook for summer water supplies is looking better, too.  “One thing that helped was the heavy rain in April and now the rain now.”

He says Seattle’s reservoir levels are above normal, and the Yakima River basin’s multiple reservoirs are just slightly below normal and rising rapidly.

“So I think we’re in pretty good shape in Washington state for the reservoirs that will supply drinking water this summer,” Mass said.

Stream levels in Western Washington are still below normal, but are rising with current rain.

Perhaps the best aspect of California’s wet weather for residents of Washington is the effects Mass expects it will have on the fire season there and the air quality here. Mass says it will push the fire season later, by keeping the grasses and vegetation that fuel their fires wet longer.

“Now eventually they’re going to dry out,” Mass said. But he expects the rains to continue for at least another week, at a time when it’s normally completely dry. Mass says this will substantially slow down the start of their major wildfires.

“So I’d expect fire season to be pushed off weeks into the future – maybe even a month further out,” he said. “That’s good news for us because during the last two years, a major source of the smoke for us, early in the season, were fires in Southern Oregon and Northern California.”

Mass says people here can expect at least a delay in the arrival of smoke coming from those areas during the early to mid part of the summer.

To hear the full conversation, 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.