It was just over a month ago that an early snow storm hit the Cascade Mountains, stoking the hopes and dreams of Northwest skiers for an above average season.
“October 8-9th, we had enough snow that it was messing up travel across the passes,” said KNKX weather expert Cliff Mass, a professor of atmospheric sciences at the University of Washington. “Now unfortunately most of that has melted. And we’ve gone into a very dry pattern.”
He points to the record dry spell that ended last week, in which the region tied a record with 14 consecutive days of no precipitation in early November.
“And right now, November is way below normal — we’re almost two and a half inches below normal at Sea-Tac, so it’s been a very dry period. And our latest computer simulations suggest that November as a whole will be dry,” Mass said.
He says the precipitation we get over the weekend and into next week won’t make much of a dent in that trend. “None of it is going to be that heavy. It looks like we’re going to be down several inches,” Mass said.
Additionally, he says, the weather has been warmer than normal, preventing any accumulation of snow.
“The snow pack is really not piling up at all. I am very pessimistic that we’ll have any kind of skiing of any type or snow shoeing in the mountains for Thanksgiving,” he said. “It doesn’t look good at all.”
BLAME HIGH PRESSURE
Mass says a pattern of very persistent high pressure over the eastern Pacific — particularly over and south of us — seems to be the cause of the drier-than-normal weather.
“We saw this last year,” he said. “And it appears to be happening again this year.”
He says with high pressure to the south of us and lower pressure to the north, atmospheric rivers tend to form, with a tongue of warm moisture being pulled out of the tropics. But the pattern often shields us from precipitation.
“And in fact one is developing right now over the Pacific,” Mass said Friday morning, adding that it will bring most of the moisture into British Columbia.
He says the cause of the high pressure is still a mystery. It could be a random set of circumstances — or there could be an underlying cause that scientists don’t yet understand.
Regardless, Mass says it’s pretty clear that the pattern is not going away.
“All the models are suggesting this high pressure’s going to continue and that’s going to result in a drier-than-normal November and not good situation for snow,” he said.
TOO EARLY FOR WINTER FORECAST
This week, a Seattle weather blogger put out a prediction that this winter will once again be severe, with as much as a foot of snow, which would be well above average. The forecast was shared by several media outlets.
Mass cautions it’s way too early to take seriously.
“Our skill drops extremely quickly after two weeks,” Mass said of forecasting.
He says forecasters have not been able to predict a lot of the major weather changes during the last few years, even a month ahead of time. “For instance, last February when we had the snow? We didn’t forecast that two weeks ahead of time.”
Mass says the skill to predict a season this far in advance is marginal at best. “And I don’t think we can bet on anything for the coming winter.”
CLIFF’S FOUR-DAY FORECAST
Friday: Morning rain to end by noon, temperatures in the mid-50s. Generally dry, except for a band of precipitation north of Seattle later in the day.
Saturday: Cloudy with temperatures in the mid- to upper-50s, as a warm front moves north toward British Columbia, with rain north of Seattle in the afternoon.
Sunday: Rain all around Puget Sound, especially in the evening and north of Seattle, as an atmospheric river pushes into British Columbia. The shift in pressure will produce gusty winds from the south during the day – maybe 15-30 mph. B.C. will get 2-5 inches of rain in the mountains.
Monday: Clouds and precipitation as a low pressure center goes south of us.
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, anda popular weather blogger. You can also subscribe to podcasts of Weather with Cliff Mass shows, viaiTunes or Google Play.
