State of the snowpack
Special to the Tribune
Leaders at the Sierra Avalanche Center — Brandon Schwartz, James Brown, and Duncan Lee — sat down on Monday to discuss the state of the snowpack after an intense dry period was followed by record levels of snow in December.
“It amazes me how it just flipped a switch. It was like nothing to everything,” Brown said about the historic December snowstorm.
From Dec. 29 to Monday, Jan. 3, and also Wednesday, Jan. 5, the avalanche danger below the treeline has been low.
“It’s one of those wonderful times that low north aspects are just so good right now — still escaping the wind,” Schwartz said.
The first large storm toward the end of October created the first layer of snow for the season, which was followed by a long dry period.
This caused a small cycle of loose, wet avalanches on southern faces.
Despite another brief storm on Nov. 9, the following dry period caused the snow to either harden on upper northern aspects or completely melt away. Eventually, the leftover snow had begun to develop facets, which cause a weak layer in the snowpack, according to Schwartz.
“Shallow snowpack is a shallow snowpack anyplace you find it… Anytime you have that structure and the low sun angles, the nights are really long even though the days are warmer out here. Low sun angles, northern aspects sitting in the shade… there’s a lot of opportunity for those snow crystals on the ground to change crystal type and turn into faceted snow,” Schwartz said.
IN THE BACKCOUNTRY
Schwartz said that toward the end of December he knew avalanches were happening, but due to the weather conditions it was difficult to observe what was happening, as the snow was piling so quickly.
Schwartz does not believe that the facets developed earlier in the season will be a problem in terms of deep instability, but that backcountry users should be looking more toward surface instability.
“You bury it deep like we’ve got and it’s a big insulation – it really minimizes that gradient and it makes things go the other way,” Schwartz said. “It makes snow get stronger and stronger… and the crystals bond together instead of becoming more individual, like grains of sugar. We’re going to be able to be past that, which is a really nice thing from a recreation standpoint.”
Brown said wind slabs continue to be a problem – which as of Wednesday is everywhere, except for west and southwest aspects, as well as low angle terrain.
In order to avoid wind slabs, Schwartz said to look out for blowing snow and trigger points where snow is drifting.
The general size of avalanche problems happening currently are up to D2, or a large avalanche, according to Schwartz and recent forecasts.
Despite the often moderate to low danger experienced in the past week, Brown warned that it is still important to be on the lookout for potential avalanches, as there is still a possibility of danger.
“I heard somebody mention the other day, ‘it’s perfect full-send conditions right now,’ and we do have these smaller avalanche problems but they can… get really real very quick with your terrain choices. So it’s generally not ‘full send’ when we still have avalanche problems.” Brown said.
To view the latest avalanche forecast or find out more information about the latest snowpack conditions, visit the Sierra Avalanche Center’s website at http://www.sierraavalanchecenter.org/forecasts/#/central-sierra-nevada.
Elizabeth White is a staff writer with the Sierra Sun. She can be reached at firstname.lastname@example.org
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