The Jackson Hole News&Guide checks in with the Bridger-Teton Avalanche Center to bring readers weekly snowpack reports and summaries. Find avalanche reports, snow conditions and new features at JHAvalanche.org. Backcountry travel in avalanche terrain is inherently dangerous. This report is not meant to replace your own information gathering, only to be one source, and is not a replacement for taking an avalanche safety course.
Weather: Jackson Hole is still adjusting after the deepest February on record. With abundant snowfall in town and the mountains, particularly in the Tetons, the snowpack has had an incredible load added to it in the past few weeks.
“In Rendezvous Bowl between the third and the 18th, we had 121 inches,” Bridger-Teton Avalanche Center Director Bob Comey said. “That’s 10 feet of snow, with 10 inches of water, over two storm cycles.”
Snowpack: The avalanche cycle during the nearly two-week loading period was fierce, with some slides during the storm that stretched from Feb. 12 to 17 dropping down through the new snow to reach the older weak layers that formed in the early parts of the season.
One avalanche on the Gros Ventre landslide with a 36-inch crown likely stepped down to some of the older layers, Comey said, and a natural release on the Pyramid just north of Wilson deposited debris all the way to the valley floor. The report on the Avalanche Center’s website said both the east and south faces failed, likely during the storm Feb. 14 or 15.
Though it can be scary to read about slides that involve that much snow, this storm might have been the ticket, at least in the Tetons, to reduce the danger of some of those older layers.
“As we get through the next few days without a big storm,” Comey said, “it’s going to settle and there will be a lot of strength in that new snow above those layers. We might be able to put some of those layers to bed.”
Comey’s optimism does not extend to the surrounding ranges. Places like Togwotee Pass and the Greys River area have had significantly less snow over the course of the season, and the same held true for these past two storms. While they did receive several feet, that snow fell in areas with well-developed weak layers and extremely poor structure.
“The problem is they got 2 to 4 feet on top of those weak layers, and now they’ll have a bunch of sleds driving around the area,” Comey said.
Outlook: We’re not out of the woods yet. Though it has been several days since something big slid in the Tetons, 10 feet of snow takes a long time to settle and bond with the snow beneath it. Settlement rates have been several inches per day, meaning that the storm snow isn’t fully rounded or bonded.
“People need to have patience and be kind of conservative,” Comey said. “We got what we were looking for, but it’s going to take some time to settle and gain strength.”
The weather looks to be variable over the next week, with an Arctic air mass having moved down from the north, bringing intermittent periods of snow and sun, and consistently low temperatures. The below-average temperatures won’t bring much more than a few inches of snow, but the sunny interludes might be the first indication of the changing seasons and the potential for crust formation.
“We’re in later February, almost March. When that sun does come out, it’s strong,” Comey said. “After the cold Arctic air leaves, it could get warm.”