Keep dreaming of a white Christmas — this year, as usual, the forecast is mostly wet | KNKX

Keep dreaming of a white Christmas — this year, as usual, the forecast is mostly wet

Dec 20, 2019

If you want to see snow on Christmas in the greater Puget Sound region, you’ll probably have to head for the mountains. Or, close your eyes and dream, as the classic holiday tune suggests.

KNKX weather expert Cliff Mass says this year — as is most common around here — there’s no chance of white stuff over the next week in most places.

“I don’t want to be a snow Scrooge,” Mass says. “But there’s virtually no chance of snow in the lowlands for Christmas.”  

And that is absolutely the norm. The National Oceanic and Atmospheric Administration’s National Climatic Data Center maintains a map with official statistics on this very question. You can zoom in to find the measuring station nearest you. It’s updated every year.

NOAA's "White Christmas" probability map. Follow the link in our story to zoom in on specific locations.

“If you look at the official NOAA statistics for Sea-Tac Airport or for Boeing Field, there’s only a 5 percent chance of getting snow — an inch of snow on the ground on Christmas Day — here in Seattle,” Mass says.  “So, it’s very unlikely, climatologically.”

That doesn’t mean it doesn’t happen. As recently as 2017, Seattle did get a white Christmas. But the far more likely scenario is for Christmas rain. NOAA puts the odds of that happening at 65 percent.

And this year, while Christmas itself may be dry and a bit cooler than it is now, the season is certainly delivering ample precipitation. On Friday morning, Mass said an atmospheric river was dumping "amazing" amounts of rain all over the region, causing many rivers to hit record flood levels.

“Just to give you an idea of some of the numbers, on the southern part of the Olympics, there are a few locations getting 6-7 inches of rain over the last 24 hours.” Mass says. “In Southwest Washington, a number of locations up there in the hills have gotten 5-7 inches of rain.”

And as much as 3 inches of rain in places such as Tacoma and South Seattle.

Mass says the atmospheric river brings warmer air with it, but in some mountain areas, the precipitation will end up as snow, building up after a poor start to the season.

“We were down to about 25 percent of normal snow pack. This event is going to bring us up at least to around 50 percent," he says. "So it’s not perfect, but it’s not going to be a disaster. And a lot of the major snow areas, from Stevens to Crystal to Baker, will be able to operate. They’ve had a foot or two of snow.”

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.