Topic Tag: level 1 refresher

ALPTRUTh is an acronym developed by Ian McCammon. The acronym identifies 7 factors that contribute to avalanche accidents. In Ian’s research, he found that over 90% of the avalanche accidents he looked at occurred when 3 or more of these factors are present. Using ALPTRUTh as a double check while in the field can be a great tool.

A: Avalanche. Have there been any avalanches in the last 48 hours?
L: Loading. Has there been any loading by snow, wind, or rain in the last 48 hours?
P: Path. Is there a noticeable and obvious avalanche path, even by a novice?
T: Terrain Trap. Is there a terrain trap present, such as gullies, trees, cliffs or other features that increase the severity of being caught?
R: Rating. Is the rating of today’s avalanche report CONSIDERABLE, HIGH or EXTREME?
U: Unstable snow. Are there any signs of unstable snow such as cracking, collapsing, or whoomping?
TH: THaw instability. Has there been recent, rapid warming of the snow surface due to sun, wind, rain, or air temperature?

Group dynamics and interactions can influence how we make decisions in the backcountry.  Understanding some of these influences will hopefully help us to better navigate them and make better decisions.

There are accident write ups available from a variety of sources. Take the time to review at least one of these accidents to understand how group dynamics, communication or lack of communication, and unclear goals can contribute to avalanche accidents.

Tunnel Creek Accident Review from the New York Times

Cherry Bowl Accident Review from the Canadian Avalanche Association

Here is a copy of the checklist to use as we go through planning a tour.

Start by looking at this avalanche forecast:

What jumps out at you? What elevations do you want to avoid? What aspects? What slope angles?

Watch this video to go through a tour plan with AAI instructor, Sarah Carpenter

How do we use the forecast and observations to put a plan together?  

It is important to have a system for planning and executing a day in the backcountry.

The AAI Backcountry Checklist provides a framework for this. The Pre-trip Plan is completed before you leave for the mountains. This section helps you identify terrain appropriate for the conditions and terrain that is off limits for the day.

The Identify Avalanche Terrain section is what should take place in the field. The goal is to prompt a continuous, focused conversation when you are approaching and moving through avalanche terrain.

The goal of the Post Trip Discussion is to continue the conversation from the mountains and to help facilitate learning. If you ask these questions each day, it can improve communication between you and your partners and provide opportunities for continuing education.

Weather is a big player in the world of snow and avalanches. Specific to winter weather, we pay attention to:

1. Precipitation
2. Wind
3. Temperature

AAI instructor, Jenna Malone, talks through the weather variables in this presentation, as well as thresholds that raise a red flag.

Snow behaves differently in different conditions. It is a material that is both temperature sensitive and rate sensitive.
In the following talk, Don Sharaf discusses why snow is like silly putty. He also talks about forces that strengthen and weaken a snowpack.

Understanding likely trigger points can be helpful in terrain selection in the backcountry. Some likely trigger spots are listed below.

Let’s talk more about how snow behaves.

How do you assess snow stability? What should you be looking for while out on a tour? Here are some thoughts on informal stability tests.

Sometimes informal stability tests aren’t enough, and you want to dig in the snow. Here is some information about snow pits and formal stability tests. We will spend time in the field using both informal and formal stability tests to assess the snowpack

There is a lot of information that one can gather on a tour. How do you sort and prioritize what you are seeing in the backcountry? Here are a few thoughts.

When thinking about snowpack, the primary question to ask is: Do we have a recipe for an avalanche?

The recipe for an avalanche consists of a SLAB, a WEAK LAYER, a BED SURFACE, and TERRAIN steep enough to slide.

Don Sharaf introduces the recipe for an avalanche and how snow metamorphism plays a part in this in the following video.

What forms a slab?

One process that forms slabs is rounding. Rounding is a strengthening process that happens at small temperature gradients.

Watch the following video to learn more about rounds, as well as other processes that form slabs.

What forms a weak layer?

One process that forms a weak layer is faceting. Faceting occurs when a large temperature gradient exists.

Let’s take a deeper dive into weak layer formation and what processes develop common weak layers.

The final component for the recipe for an avalanche is the bed surface? What processes form bed surfaces? How do you recognize them? Watch this final video to learn more.

Route planning starts long before you head out on a tour. Here are a few tips as you begin route planning.

In rare cases of wet slab avalanches or slush avalanches, these rules of thumb for alpha angle may not apply. These avalanches might run further.

Downloadable apps for measuring runout angles include:

https://wbskiing.com/inclinometer.php

https://play.google.com/store/apps/details?id=com.glidelinesystems.dioptra&hl=en_US