Avalanche Danger Is Exponential, Not Linear: A Safety Editor's FAQ

Imagine you're standing at the top of a backcountry line, the snow looks perfect, and the forecast says 'Considerable.' You think, 'That's just one step above Moderate, right? How bad can it be?' Then you drop in. That mindset kills people. I'm here to tell you: the North American avalanche danger scale is not a gentle slope—it's a staircase with missing steps. The danger increases exponentially between levels, not linearly (Avalanche danger scale). So 'Considerable' is not a small bump from 'Moderate'; it's a leap. And 'High' is a different universe. I've been guilty of underestimating this myself, and I've seen friends do it. So let's bust some myths.

Is 'Considerable' danger really that bad?

Yes, it is. At Considerable, natural avalanches are possible and human-triggered avalanches are likely (Avalanche danger scale). That means if you're on a slope steep enough to slide, you could be the trigger. I treat Considerable as my personal red line for anything but the simplest terrain. If I'm touring, I stick to low-angle, well-supported slopes and avoid convexities and gullies. The exponential jump means the consequences of a mistake at Considerable are far worse than at Moderate. Don't be fooled by the middle-of-the-road name.

Can I just rely on the resort's avalanche control?

Inside ski area boundaries, yes—resorts do extensive control work. But that doesn't make you invincible. In the 2024/25 season, U.S. ski areas reported 50 skier and snowboarder fatalities, a rate of less than one per 1 million skier visits (NSAA fatal incident fact sheet). Collisions with trees were the leading cause, accounting for nearly half of all deaths (NSAA fatal incident fact sheet). So even inbounds, you need to ski in control. I always tell people: the resort manages the snow, but you manage your speed and your line. And if you're venturing out the gates, you're on your own.

Do helmets prevent avalanches?

No, that's a dangerous misconception. Helmets protect against head injuries, not avalanches. A 2010 meta-analysis in CMAJ found helmeted skiers and snowboarders were significantly less likely to sustain a head injury, with a pooled odds ratio of 0.65 (Helmet meta-analysis (CMAJ 2010)). In kids under 13, the protection was even stronger (odds ratio 0.41). But a helmet won't save you from being buried. Avalanche survival depends on carrying a beacon, probe, and shovel, and knowing how to use them. I wear a helmet every day, but I never let it give me a false sense of security in avalanche terrain.

Are tree wells a real threat?

Absolutely. Tree well and deep snow immersion accidents happen when you fall into unconsolidated snow and suffocate—known as snow immersion suffocation (SIS) (NSAA tree well safety). In 2024/25, snow immersion incidents, including tree wells, represented roughly ten percent of ski-area fatalities (NSAA fatal incident fact sheet). That's a significant chunk. I never ski glades alone, and I always keep my partner in sight. If you're in deep powder near trees, stay close and carry a whistle.

What about the danger scale's elevation bands?

Ratings are typically provided for three distinct elevation bands (Avalanche danger scale). So the danger at the trailhead might be Low, but up high it could be High. I always check the forecast for the elevation I plan to ski. And remember Parks Canada's advice: when the rating is High or Extreme, avoid avalanche terrain entirely and stick to simple terrain or stay in bounds (Avalanche danger scale (Parks Canada)). That's not being timid; that's being smart.

Quick tip: Before you head out, check avalanche.org for your local forecast and read the full discussion, not just the rating.

One more thing: the number of U.S. avalanche fatalities has stayed relatively stable at about 25 to 30 per year since 1995, even as backcountry use increased 8-fold (Avalanche fatality trends (WEM/USDA)). That's a testament to better education and gear, but it also means we can't get complacent. The stakes are high. So my single most important piece of advice: take an avalanche course, carry the right gear, and always make decisions as if the slope could slide. Because sometimes it will.

Sources

• Avalanche danger scale - https://avalanche.org
• NSAA fatal incident fact sheet - https://nsaa.org/webdocs/Media_Public/IndustryStats/fatality_fact_sheet_2025.pdf
• Helmet meta-analysis (CMAJ 2010) - https://pubmed.ncbi.nlm.nih.gov/20123800/
• NSAA tree well safety - https://www.nsaa.org/NSAA/Safety/Tree_Well_Deep_Snow_Safety/NSAA/Safety/Tree_Well_Deep_Snow_Safety.aspx?hkey=a51384bb-5400-460c-85e6-6fe23bc14ff4
• Avalanche fatality trends (WEM/USDA) - http://avalanche.org/wp-content/uploads/2018/07/17_WEM_Birkeland_etal_AvFatalities.pdf
• Avalanche danger scale (Parks Canada) - https://www.parks.canada.ca/pn-np/mtn/securiteenmontagne-mountainsafety/avalanche/echellerisque-dangerscale