Avalanche Season Is Here
Northwest Avalanche Center talks about how to prepare for and spot the hazards of high country travel in winter. Brush up your basics and warm up your brain for cold season safety.
Did you know that some of Washington's most popular summer hiking trails cross serious avalanche chutes? Can you spot and assess the risk on trails covered in snow? You don't need to be wearing snowshoes or skis to put some basic avalanche awareness into practice as you hike this winter. And our friends at the Northwest Avalanche Center are experts in giving you the tools to stay safe. Warm up your brain for the cold season, and get tips for checking conditions before you head into the mountains.
This blog was originally posted on the Northwest Avalanche Center blog.
by Forest McBrian, NWAC Education and Operations Manager
October in the Pacific Northwest typically sees the arrival of the first tantalizing storms, and people begin to anticipate the true beginning of winter in the mountains. It is a time when careful research can pay off with some good turns or a rewarding ascent, and the fall colors alone are enough to entice you to go have a look. However, it is also nearly a month before NWAC is likely to begin issuing daily avalanche advisories.
So how can we manage our risk in the weeks leading up to full-blown ski season?
Remember the basics
Identifying avalanche terrain can be tricky in early season. Although the landscape around you may seem sparsely snowed, the slopes above may have a much deeper snowpack. In these conditions, crossing an avalanche path may not put you at risk of triggering a slide, but it could expose you to hazards from above.
The best time to begin identifying avalanche terrain is before you start your trip; use maps, guidebooks, and photographs to gather information about your destination. In particular, the leeward side of high ridges are most likely to harbor significant snow drifts. It may be difficult to determine if these have enough mass to produce loose snow or slab avalanches, and even harder to tell how far they may run if triggered.
Red flags are red flags
Red flags are obvious signs that avalanche danger is present or increasing, and they are helpful even without an avalanche advisory. Backcountry travelers learn to recognize them as useful data requiring little interpretation.
Red flags include:
- Recent avalanches
- Wind loading
- Heavy snow or rainfall
- Significant warming
- Signs of unstable snow (cracking or whumpfing)
When you see any of these signs, it’s a good idea to move to a safe spot and to check in with your partners and with your plans. Ask yourself if your route might expose you to avalanche hazard, and if there is a way to avoid it. If you aren’t sure, adjust your plans accordingly.
Consider ground cover
Areas with brush, big boulders, and dense trees may anchor the snowpack in early season, making it difficult for a slab to form and release. Conversely, areas with smooth ground cover–including rock slab, scree, dirt, grass, heather, snowfields, and glacial ice–offer no anchoring whatsoever.
With our typical autumn temperature fluctuations, warming can easily produce melt water and cause the entire, young snowpack to slide off. This type of avalanche–termed a glide or full depth avalanche–is typically associated with the spring, but may occur at any time.
Use all your resources
The avalanche forecast season may not have begun, but NWAC still offers resources; check back often for Seasonal Statements (via the homepage map) and Recent Observations. Trip report sites like Turns All Year, NW Hikers, and Cascade Climbers can offer precious insights into current conditions.
Track the early season snow
In cooler parts of the intermountain west, early season storms frequently produce weak layers that can linger, sometimes for the entire season. To understand why this is the case, it helps to dust off your snow science brain. When you combine cool temperatures, thin snowpack, and low density snow, you have conditions that favor a metamorphic process called faceting. Faceting snow grains grow big angular edges, making them less willing to form strong bonds with adjacent grains. Taken to its extreme, the faceting of early season snow can produce depth hoar, a very developed and super-weak type of snow grain.
Although our relatively warmer temperatures and deeper snowpack tend to prevent these early season snows from becoming persistent weak layers, our accident record includes examples of fatal avalanches that fractured on grains formed in October or November. Since we can’t know what weather events will unfold, we have to track these early season layers carefully. Ski patrollers, guides, and our Professional Observers are all paying attention as the freezing levels rise and fall this month.
Beware of shallow snow hazards
In addition to growing potential for avalanches, this is the season of the “shark”–thinly buried obstacles that can catch a ski or board. It's New, soft snow can be treacherous to travel through when it hides boulders, downed logs, and other obstacles. Choose your route carefully!
Now is the perfect time to review that course manual from your last avalanche course, or to sign up for a new one. The skills we acquire in our avalanche education are perishable–we have to keep them up, or risk losing them. There are countless ways to continue your avalanche education: read a book, watch a movie, take a course; best of all, attend an upcoming class or workshop. They are a great way to learn about current research in snow science and avalanche safety, and to connect with the mountain community.
NWAC is here to equip and empower backcountry travelers in the wintertime mountains, and we are a community effort. Take a class, host a class, become a member, post an observation, send us feedback -- we welcome your involvement, and look forward to seeing you in the mountains this winter.