BOISE, Idaho — This article originally appeared in the Idaho Press.
If you were dreaming of a white Christmas this year, the Treasure Valley’s skies let you down.
The question is, are warmer Decembers and snowless Christmases just a result of the weather’s natural ebb and flow, or is it something more?
In the past 30 years, the average winter snowfall in Boise has decreased by about two inches, meteorologist Spencer Tangen said in an interview with the Idaho Press. Temperatures have also increased, particularly in the summer months.
“Our average temperature height climbs a couple degrees across July and August, and our winter temperatures went up a little bit too,” Tangen said.
The valley has also experienced less snowfall and higher temperatures in the past 10 years.
“We can still have a snowy winter here, but they’re, on average, getting less frequent. And the really cold temperatures are a lot less frequent than they used to be in the ‘70s and ‘80s,” Tangen said.
This month, Boise has averaged four degrees above the typical December temperatures.
“It has been a more mild December,” Tangen said. “In terms of snow, we have had 3.8 inches this month, and normal for the whole month is 5.6, so we’re almost two inches below normal.”
December and January nearly tie for the coldest month on average in Boise, Tangen said, with December averaging 5.6 inches of snow and January averaging 5.3 inches of snow.
Last December, he said, Boise had 9.4 inches of snow.
Precipitation has been pretty close to normal, Tangen said, with about 1.51 inches of rain and melted snow this month.
Those averages are pulled from the National Weather Service’s 30-year climate normals, which run from 1991 to 2020, Tangen said. Winter temperatures and precipitation impact the reservoir storage for the Boise River, which, thanks to last year, is currently above normal, Tangen said.
“We had a really wet year last year,” he said. “So that allowed some of the water to carry over.”
Bogus Basin has also been impacted by the light winter.
“This year, we have really had a chance to test the limits of our snowmaking system for the first time since we put it in in 2018,” said General Manager Brad Wilson. “We are providing some really good conditions and some good skiing. If we did not have snowmaking we would not be open right now.”
The recreation area is down 25% in visits compared with last year, Wilson said in an interview with the Idaho Press. Typically 25-30% of their revenue is generated from the two weeks of Christmas and the New Year’s holidays, Wilson said, but the ski season’s peak is generally around January or February.
Their snowmaking system was donated by the community in 2017, according to Susan Saad, Bogus Basin’s Director of Community and Customer Relations.
“That’s why we’re open now: because of community support,” Saad said.
The mild December weather could be caused by a ridge of high pressure across the West, which keeps the flow of air coming from the west or southwest, as opposed to the colder air from the north, Tangen said.
“When we get air coming out of the north or northwest, that’s when we get our colder storms and we see more snow,” Tangen said. “If we get storms that come right out of the Gulf of Alaska or out of like British Columbia, those are typically containing a lot more cold air. They have a lot more Arctic influence.”
It’s too early to say if the rest of the winter will follow this month’s trend though.
As of Thursday, the weather service forecast predicted some weak storms coming through Boise on Sunday, Tuesday and Wednesday next week. And the second week of January could bring colder temperatures and snow, Tangen said.
Typically, by March, Boise’s snow begins to taper off and the valley starts to warm up. Although, last year Tangen said was one of the snowiest March’s Boise has ever had.
This article originally appeared in the Idaho Press, read more on IdahoPress.com.
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