Cold and snow expected in PNW from Arctic blast
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The Pacific Northwest is expected to see freezing temperatures and maybe even lowland snow this week as part of the polar vortex blasts southward from the Arctic.
Driving the news: Snow in the lowlands of Western Washington and Oregon is notoriously difficult to predict, but there is a 45% chance that the lowlands — including Seattle — could see more than 4 inches between Friday and Saturday, Dev McMillian of the National Weather Service (NWS) in Seattle told Axios.
- In Portland, things will start earlier with snow accumulation possible Wednesday in some areas, such as in West Hills, with potential impacts on the morning commute, per NWS Portland hydrologist Andy Bryant.
- On Saturday, Portland is likely to see 1–3 inches of snow, Bryant told Axios.
The intrigue: Forecast models are all over the place, with some showing mostly rain in both cities and at least one on Tuesday showing a potential for Seattle to see as much as 10 inches of snow and for Portland to see 8.
Yes, but: There's only about a 10% chance of that extreme snow scenario happening, according to Michael Fagin, who writes snow forecasts for area ski resorts.
Why it matters: With nearly 4 feet of snow expected in the Cascades between now and Saturday and temperatures possibly 10 to 18 degrees below average, travel could be tricky, Fagin said.
What they're saying: "It's already pretty treacherous in the mountains and will get more so through the week," said Bryant.
What's happening: Temperatures will begin to drop significantly on Thursday, per the weather service, when cold air streams into Western Washington and Oregon from Canada.
- From Friday morning through Saturday, Seattle is expected to see temperatures in the low 20s or even the teens, said McMillian, potentially 18 degrees below the average January low of 38.
- Temperatures around 25°, or 10–15 degrees below the monthly average, are expected in Portland during that same period, per Bryant.
State of play: NWS forecasters are confident that cold temperatures will arrive by the end of the week; the big question is how much moisture will be around, local meteorologists said.
What we're watching: Next week looks cold too, per the NWS.