Article By Anna
This article is intended to give basic insight into various aspects of how to interpret information and make safe decisions in avalanche terrain. This is not a substitute for more extensive learning including reading some of the excellent avalanche safety books available, the various avalanche safety videos and articles put out by professionals, and, most importantly, taking an avalanche safety class (or two or more).
Unfortunately, every winter, the lives of a handful of recreationalists are claimed by avalanches. It's easy to blame these deaths on ignorance. Or on snowmachiners, ya know just being snowmachiners. Or on a variety of other factors. The reality is that often, it isn't the noob out there that gets caught. There have been numerous near misses and fatalities that have happened to people extremely skilled and educated in avalanche safety. Safe backcountry travel is a myriad of judgments and assessments that one must continually make to make it home safe. These decisions start before you even step out the door. Savvy recreationalists will check their local forecast before ever arriving in avalanche terrain. Proper awareness of the risk that each danger level of the avalanche forecast indicates is critical to planning a safe ski trip.
Did you know that statically, the most avalanche deaths occour when the forecast is at "Considerable"? (1) Most people, aren't going to knowingly go into dangerous avalanche terrain when an "Extreme" forecast is in effect. The same goes for a "High" forecast. Something about the black and red and the Xs kind of seem paint a bad picture that tends to scare people off. However, once the forecast goes down to "Considerable", many people deem their avalanche assessment skills strong enough to accept the level of risk presented by "Considerable" conditions. Often the "Moderate" and "Low" forecasts yield conditions that are stable enough that avalanches are less likely and smaller in scale if triggered. There is a decent chance of just getting lucky on a "Low" day, education and skills be damned. That said, the most important thing to remember is any snow on a slope is enough to slide and cause an avalanche that can kill you.
Read through what each of those mean. Does anything in the "Considerable" description make you feel warm and fuzzy? Human triggered avalanches likely? No thanks. Possibility of random freak natural avalanche releasing unexpectedly? Nope. Small avalanches in many areas? Again, a polite "fuck no thanks" to that. A possibility of large or very large avalanches? I mean what do we mean by possibility? Is this like a 5% or a 50% chance here? Is a 5% chance of a "very large" avalanche worth it? The orange color and pretty orange mountain logo with a few "!!" might indicate something more fun than likely avalanches, but reading the words throws up a lot of flags in my brain.
Some things to consider when interpreting your local avalanche forecast:
- The North American Danger scale is not linear. If a "Low" rating is a 1, then a "Moderate" rating is a 2. However, a "Considerable" rating is a 4 and a "High" rating is an 8. According to the scale, a "Considerable" rating is four times more dangerous than a "Low" rating. It should be noted that avalanche forecast ratings can vary depending on the country issuing them. If you are skiing oversees, be familiar with how the danger scale for that country works.
- The danger scale gives an overall danger rating for a large area. Just because the overall forecast area is rated "Moderate" does not mean there are not isolated areas that would receive a "Considerable", "High", or even "Extreme" rating if evaluated.
- The danger scale does not include the type of danger present. Four inches of medium dense storm snow on hoarfrost poses a different threat than a deep persistent slab which poses a different threat from recent wind loading. While a forecast may be "Moderate", there could be a deep persistent slab that is not likely to be triggered. If it is triggered, it will most likely be large and will certainly be unpredictable.
- Just because the forecast stats one rating in the morning does not mean it will not change over the day. Changing conditions throughout the day can cause the actual rating to fluctuate into general increased or decreased stability. Often the forecast will note likely changes to the snowpack throughout the day.
- For a "Considerable" rating, small avalanches are likely. Even small avalanches can be deadly, especially if terrain traps are present. The term "Considerable" was added to the forecast criteria in 1996 to address what was previously known as "Moderate to High" danger. (2)
- A "Low" rating on the forecast does not mean that backcountry travelers should not constantly asses conditions. Careful evaluation of conditions should be an integral part of every backcountry outing. Avalanche fatalities have and will occour at any danger rating.
When making decisions in avalanche terrain, keep in mind that the forecast is just a general starting point to use as you gather your own information and form your own opinions regarding the conditions, danger, and overall stability. Keep in mind that a "Considerable" rating used to be known as a "Moderate to High" rating; according to any statistic you look at, around half of all avalanche fatalities occour during "Considerable" conditions.
Stay safe out there. Live to ride another day.