Guide to Understanding Avalanche Advisories
Whether you're a snow veteran or a first-time shredder, this guide equips you with essential skills to navigate and interpret avalanche advisories effectively. From beginners to seasoned adventurers, everyone gains a grasp of forecast fundamentals. Crafted by avalanche experts, riders, and snow aficionados, this guide decodes the intricacies of avalanche forecasts. Feel confident in decoding vital info, ensuring your snowy escapades are not just thrilling but also seriously on point when it comes to safety.
Keep in mind that while avalanche advisories are crucial, they serve as broad descriptions of conditions in a general area, not specific slopes. Backcountry adventurers are urged to learn how to gather their own information, honing the skill of spotting avalanche danger.
Avalanche Danger Ratings
The avalanche danger scale, a key component of avalanche forecasts, features five levels: extreme, high, considerable, moderate, and low. It's crucial to note that this scale isn't linear. The risk grows exponentially with each level, doubling as you move up. Going from "low" to "moderate" means taking on twice the risk, and from "low" to "extreme," it's nearly 16 times more perilous.
We strongly emphasize treating a "high" rating as the pinnacle of danger, something to steer clear of. "Extreme" conditions are exceptionally rare and perilous – it's just plain foolish to venture into avalanche terrain during such times. The scale may somewhat downplay mid-levels, which are deceptively more hazardous than they appear. Surprisingly, most avalanche fatalities occur in "considerable" conditions, where the line between safety and danger becomes harder to discern. Stay informed and exercise caution in the mountains.
| Danger Level | Travel Advice | Likelihood | Size & Distributions | |
|---|---|---|---|---|
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Low (1) | Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. |
Natural and human-triggered avalanches unlikely. |
Small avalanches in isolated areas or extreme terrain. |
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Moderate (2) | Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. |
Natural avalanches unlikely; human-triggered avalanches possible. |
Small avalanches in specific areas; or large avalanches in isolated areas. |
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Considerable (3) | Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. |
Natural avalanches possible; human-triggered avalanches likely. |
Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. |
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High (4) | Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. |
Natural avalanches likely; human-triggered avalanches very likely. |
Large avalanches in many areas; or very large avalanches in specific areas. |
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Extreme (5) | Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain. |
Natural and human-triggered avalanches certain. |
Very large avalanches in many areas. |
Avalanche Problems
Avalanche problems offer an in-depth look into current conditions, such as the types and sizes of avalanches you can expect in the area, the likelihood of a slide, and the aspect and elevation or where you can expect a slide. These graphics help travelers know what to expect—where the risk is and the characteristics of a potential slide.
The Avalanche Danger Rose
A common avalanche problem is the Avalanche Danger Rose. This graphical illustration was designed to provide critical avalanche information at a glance. The danger rose consists of three rings representing elevation. These rings are further divided into subsections based on cardinal directions. Each pedal or subsection of the rose indicates an aspect and elevation. These subsections are color-coded to the avalanche danger scale. The avalanche danger rose will help you find the danger level for each direction and elevation.
In this example, there is considerable (level 3 - orange) avalanche danger on slopes above 9,000 feet facing north, northeast, and east.
Travel Advice
The travel advice section included in most advisories helps backcountry travelers know how to behave out on the snow. Travel advice is the opinion of a backcountry expert based on their own travels during the forecasted period. Give attention to descriptions or photos to know what terrain you should avoid while recreating.
Weather Forecast
Most avalanche advisories include a summary of the most relevant trends in snow and weather over the previous 24 hours. These summaries generally include details related to precipitation, snowfall, wind, temperature, and sunlight. Avalanche conditions are directly related to weather conditions. Understanding how weather affects snowpack can help riders determine how evolving conditions shape future risk.
The Bottom Line
Commonly, each avalanche forecast includes a short paragraph on what can be expected throughout the day. The "bottom line" is typically a brief, one-paragraph summary of the entire forecast.
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THE BOTTOM LINE
The combination of recent snow, wind, and buried weak layers make human triggered avalanches possible today. Monitor the wind direction as well as the influence of the sun and pay attention to signs of instability such as cracking within settled and drifted snow or audible collapsing of the snowpack. Steep and rocky areas that have been affected by the wind or the sun over the last week are the most likely areas to trigger a slab.