Why You Should Ski the Trees at Considerable Danger

You've heard it a thousand times: when the avalanche danger is Considerable, stay out of the trees. Stick to the open slopes, the groomers, the mellow terrain. It sounds prudent, but it's backwards. In a typical winter backcountry scenario, the trees are often your best ally—if you know how to read them. As a working ski guide, I've learned that the danger scale isn't a simple green-yellow-red light. It's a nuanced tool that, when understood properly, can actually point you toward safer skiing.

The Considerable Trap: Why We Overreact

Let's set the scene. It's a Tuesday morning in the Rockies. The avalanche forecast says Considerable danger at treeline and above. The sun is out, the snow is stable on test slopes, and you're itching to ski. Most people hear "Considerable" and think "dangerous." But here's the thing: Considerable doesn't mean everywhere is dangerous. It means that human-triggered avalanches are likely, and natural avalanches are possible (avalanche.org). That's a serious warning, but it's a warning about specific terrain, not the whole mountain.

The trap is that many skiers respond by avoiding all "avalanche terrain," which they interpret as any slope steeper than 30 degrees. They end up on a boring, low-angle slope that's actually more exposed to wind-loaded pockets and terrain traps. Or they stay in bounds, where the ski patrol has already mitigated the risk, but they miss the point of going into the backcountry in the first place. The smarter move is to use the danger scale as a filter, not a blanket ban. And that's where trees come in.

Reading the Danger Scale Like a Pro

The North American Public Avalanche Danger Scale isn't just a measure of how likely an avalanche is. It also incorporates the size and distribution of expected avalanches (avalanche.org). At Considerable, you might have pockets of unstable snow on specific aspects and elevations, while other slopes are perfectly stable. The scale is also provided for three elevation bands, so the danger at treeline might be different than above treeline (avalanche.org).

Here's the key insight: avalanche danger increases exponentially between levels, not linearly (avalanche.org). That means the jump from Moderate to Considerable is bigger than from Low to Moderate. So even though Considerable might sound like just one step up, it's a significant shift in the likelihood of triggering a slide. But that doesn't mean you have to stay home. It means you have to be more selective.

So how do you select? You look for terrain that minimizes the consequences of a slide, even if the likelihood is elevated. Trees, when they're dense enough, can act as natural anchors. A slide in a tight tree run is less likely to propagate, and if it does, the trees break up the snow and slow it down. That's a game-changer.

The Tree-Run Strategy: A Field Report

Imagine you're a group of experienced backcountry skiers. You've checked the forecast: Considerable danger at treeline, Moderate below. You have a choice: ski a wide-open, 35-degree bowl or a 30-degree tree run with scattered pines. The bowl is tempting—it's beautiful, and the snow looks perfect. But the open slope is a classic avalanche path. If a slide releases, you're in the middle of it, with no trees to grab onto. The tree run, on the other hand, has trees spaced about 10 feet apart. The slope is still steep enough to be fun, but the trees break the slope into smaller pockets. Even if you trigger something, the slide will likely be small and slow, and you might be able to grab a tree.

This isn't just theory. Avalanche fatalities in the U.S. have remained stable at about 25 to 30 per year since 1995, despite an 8-fold increase in backcountry use (avalanche.org). That's not because skiers are getting safer—it's because they're getting smarter about terrain selection. And a big part of that is using trees as a safety feature.

Comparing Tree Runs vs. Open Slopes at Considerable

Let's break down the decision with a comparison:

Notice the trade-off: tree runs reduce avalanche risk but introduce tree-well risk. Snow immersion incidents, including tree wells, accounted for roughly ten percent of ski-area fatalities in 2024/25 (NSAA). That's a real concern, but it's manageable. Ski with a partner, stay in sight, and carry a beacon, shovel, and probe—even in trees. The key is to pick trees that are dense enough to anchor the snow but not so dense that you can't escape a slide.

The Bottom Line: Choose Your Risk Wisely

When the danger is Considerable, don't just look at the slope angle. Look at the terrain features. Trees are a form of terrain management. They reduce the size of a potential slide and give you something to hold onto. In contrast, an open slope is a highway for a slab. The avalanche danger scale is a tool, not a dictator. It tells you the likelihood and size of avalanches, but it doesn't tell you where to ski. That's your job.

So next time you see Considerable on the forecast, don't automatically head for the groomers. Consider the trees. Ski them with respect, with a partner, and with the right gear. You'll get better turns, and you'll be safer. That's not just my opinion—it's the math of avalanche risk.

Sources

• Avalanche danger scale - https://avalanche.org
• Avalanche fatality trends (WEM/USDA) - http://avalanche.org/wp-content/uploads/2018/07/17_WEM_Birkeland_etal_AvFatalities.pdf
• NSAA fatal incident fact sheet - https://nsaa.org/webdocs/Media_Public/IndustryStats/fatality_fact_sheet_2025.pdf