By Hannah Hickey and Kiyomi Taguchi
After many people in the Puget Sound region had dismissed any chance of snowfall in the lowlands this season, the region is now on track for not one, but two, and possibly even more snowstorms this winter.
Nick Bond, a University of Washington associate professor of atmospheric sciences who serves as Washington’s official state climatologist, commented Thursday on the upcoming snowstorm – the second to hit the Puget Sound region this week.
It’s not a coincidence that we’re getting even more snow – the situation on the ground matters for the coming snowstorm, Bond said. Because the ground is already cold, that will chill the air enough that this storm will likely bring snow from the start, instead of rain followed by snow. Also, this cold spell means that snow will likely last on the ground longer.
“It is a very unusual situation we’re in, which is sustained cold weather,” Bond said. “Oftentimes, the atmospheric circulation patterns get into a state that’s favorable for snow, but because it’s a rare event, it just doesn’t hang around that long. Then we get back to more air coming off the Pacific Ocean that’s relatively mild, and a return to more normal temperatures.
“But in this particular case, we’ve just kind of gotten locked into a pattern where we’re going to continue to get colder air from the north, along with that special set of circumstances in which we can get the lift, the precipitation, and the snow to fall. It doesn’t happen very often – maybe every decade, or even two, that you have something like this. So it’s quite remarkable.”
Bond defers to the National Weather Service for exact predictions, and notes that the exact timing and location of the heaviest snowfall is hard to predict. But he expects it to be a more unusual event in the lowlands than at higher elevations.
“These patterns aren’t really huge snow producers for the mountains,” Bond said. “They don’t produce a great deal of total precipitation, so it’s not the most favorable for really piling up snow in the mountains. But they will get some, and our snow pack right now is a little below normal. We’re not panicking, but there is some concern about water supply next summer. So hopefully they’ll get some, too.”
Bond is a member of the Joint Institute for the Study of the Atmosphere and Ocean, a collaborative research center between the UW and the National Oceanic and Atmospheric Administration.
The air that is hitting us is not the same mass of cold air that hit the Midwest a few weeks ago, but the two events are somewhat related, Bond said.
“If you were to track the wind patterns, and ridges of higher pressure and troughs of lower pressure, sometimes the overall pattern around the whole Northern Hemisphere will be more circular — very symmetric,” Bond said. “Other times, it has these big ridges and big troughs, so there are places with strong north winds and strong south winds. So we’ve been in one of those kind of wavier patterns.”
One common question in the media is whether the “polar vortex” might be destabilized, sending more Arctic air into the mid-latitudes under global warming. Bond said that with a short record and evidence on both sides, the jury “hasn’t even been called yet” to establish if that connection exists.
As for whether this cold snap disproves global warming, Bond said the answer is clearly no.
“This is weather, not global warming. 2018 was by most measures the fourth-warmest year on record. But these sort of cold-weather events will still happen.”
And the cold seems likely to stick around.
“Right now, it looks like it’s going to stay cold for an extended period — at least another week or so, maybe a little bit longer,” Bond said. “It won’t necessarily be bitterly cold, but below-normal temperatures. The crystal ball starts to get really fuzzy when you start to look longer than a week or so, and it doesn’t really imply anything for the spring.”