Avalanche awareness: An update on this season’s snowpack
It’s in March that the spring itch to get outside really hits. The sun makes warm afternoons and legs are strong from weeks of skiing and confidence is high from weeks of snowmobiling. All in all, it seems like the perfect time of year to hit the backcountry.
But the warm weather brings dangers to backcountry users. And while most users know to check the Bridger-Teton Avalanche Center’s daily forecast before heading into the backcountry, it never hurts to remember the dangers avalanches pose to those of us enjoying the snow-covered great outdoors. Peaks to Plains caught Bob Comey, lead forecaster and director for the Bridger-Teton Avalanche Center to talk about the changing risks of spring skiing and snowmobiling as well as to discuss this winter’s snowpack so far.
Peaks to Plains: Talk about the snowpack so far this year:
Bob Comey: This year started with a moist December and then a dry January and then intermittent February storms. We’ve got areas that have deeper snow and some with shallower snow and then intermediate areas in between. … We’re below average everywhere. There are some places where we’re at 95 to 85 percent of average. Then there are some places that are like 70 percent or less of average. In those shallow places, the snow becomes faceted, which is weak, there’s depth hoar (large grain faceted snow), then new snow on top of it. Then there are two things we’re concerned about, new storms come in and create the new snow and the snow and wind makes the surface unstable, and then there’s that deeper instability. When the shallow areas with that deeper instability get new snow it forms persistent slabs. … On steep slopes, snowmobilers and skiers could trigger snow that’s acquired since January. It’s hard to determine which slopes are unstable. There might be a few out there that could fail and a few out there that are fine. It’s really hard to determine which slopes those might be. In the deeper areas, where we are looking at a snowpack of 4 to 8 feet deep, there is enough strength the persistent slab is generally not a concern. Those areas, we’re looking at new storms that come in and create instability and it’s about just trying to manage the hazard on the surface of the snow.
P2P: Where are you seeing the shallower snowpack and the deeper snowpack?
BC: It’s somewhat elevation determined. But we’re seeing (shallow snowpack) on the east side of the Continental Divide. There’s also a shallow snowpack on the East side of the Wyoming Range. … There’s a deeper snowpack situation in the Tetons and the Salt River Range and the southern part of Yellowstone. There’s intermediate stuff along the continental divide and on the west side of it, as well as in some areas of the Wyoming Range and the Salt Mountains.
P2P: How does this year’s snowpack compare to last year’s?
BC: Last year we had an early snow in October and then a drought period. Then we got a big storm between Christmas and December that caused instability, then February was pretty good. We’re in a kind of similar situation this year. … Last year it just suddenly stopped snowing and got warm on like March 3. It was really unusual.
P2P: Talk about spring skiing. What do we need to look for or do differently in our slope assessments as we are evaluating avalanche terrain?
BC: We get into that melt-freeze cycle in the spring with cold clear nights and warm sunny days. The snow starts to metamorphose. … Backcountry travelers are safer in the early mornings and then as it warms the hazards increase. It becomes quite hazardous in the warmest part of the day. The snow loses strength in the afternoon due to the warming. Then it freezes at night. So if it doesn’t freeze at night, then we really need to be concerned. If it’s warm through the night, the snow doesn’t get stronger. And if we get a lot of rain — rain on snow (is a) red flag. People really should focus on weather all the time, but especially in the spring regime where conditions are changing quickly. The bottom line is how hard is the snow surface. If the conditions start to soften, start thinking about what you are doing. If it’s really soft, think about not being in avalanche terrain at all.
P2P: The avalanche center revamped its website this year. How has that gone over with users?
BC: We made some changes to the format, but the information we always provided is still there. The presentation is a little different and we have more information. We’ve added avalanche problems, like what type of hazards are in areas. The idea is people would manage different hazards differently. We’ve gotten feedback people like the information but we don’t know if they are using it the way we intended, to change how they evaluate terrain and hazards. … Right now you can look at the map and see the forecasts for extended areas. We want to expand that to Utah and Colorado, working with those avalanche centers. … We’ve had a big increase in visitors to the site and a huge increase in page views. People are coming to the site and spending more time and checking it more than just once in the morning.
P2P: I know many avalanches are undocumented because someone has to actually see it and report it. But how is this year looking compared with last year and previous years as far as avalanche activity?
BC: I’d say it’s pretty standard, but we haven’t had as many large avalanches this year. Avalanches are rated on scales from one to five with five being the biggest and one being the smallest. We haven’t seen any fives, which isn’t unusual. Fives are so big we usually only see them every 10 years or 30 years on avalanche paths. However we haven’t seen many fours or three this year.
P2P: There have been three avalanche deaths so far this year in Wyoming. How does that compare to other years?
BC: It varies year-to-year. But if you look at the deaths on our Wyoming fatalities page, by decade, it averages out to about three a year.
P2P: Wow, there’s a big jump in fatalities in the 2000s, from the 1990s.
BC: Yeah, I think that just shows the increase in backcountry users and also what people are doing, where they are going and when.
P2P: Anything else about this year we haven’t touched on?
BC: Yeah. The three fatalities this year were unusual because they were in small avalanches on low hazard days, but on pretty steep terrain. All three died on site at the time of the incident due to trauma. No one was fully buried.
P2P: You’ve emphasized that steep extreme terrain is kind of its own beast and that the forecasts from the center shouldn’t impact decisions on steep terrain.
BC: Yes. Our reports are for general avalanche hazards in general terrain. Extreme terrain is exclusive of the general avalanche hazard forecast. In extreme terrain, it’s almost always dangerous. That’s a whole different sport.
— “Peaks to Plains” is a blog focusing on Wyoming’s outdoors and communities. Kelsey Dayton is a freelance writer based in Lander. She has been a journalist in Wyoming for seven years, reporting for the Jackson Hole News & Guide, Casper Star-Tribune and the Gillette News-Record. Contact Kelsey at [email protected]
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