February 18, 2011 - Update

We titled our newsletter “Low probability/ high consequence avalanches” to note that while the current Avalanche Danger Rating is not posted as ‘HIGH’ the consequences of triggering an avalanche right now could be very devastating.

CLICK HERE to read Zac’s Tracs latest newsletter
BE SURE TO COMMENT on this article as well! CLICK HERE to submit!

To offer a bit of background: a danger rating of ‘HIGH’ means that ‘the chances of NATURALLY triggered avalanches is LIKELY’. Right now the avalanche ratings for most areas are posted as ‘CONSIDERABLE’or‘MODERATE’. Please read this to mean that while the chance of an avalanche ‘triggering NATURALLY has dropped to POSSIBLE, HUMAN triggering is still LIKELY or POSSIBLE’ if we choose to travel in the weaker snowpack zones.

But we spend much of the year with Considerable and Moderate ratings and what is so special about now?
Right now the hard to predict instability is in the bottom of the snowpack. This means the potential for LARGE, high consequence avalanches. This is in contrast to other times in the season when avalanches may be more easily triggered in layers closer to the surface of the snowpack, often leading to smaller, less destructive avalanches.

CLICK ON THIS LINK to read the full CAC report as posted in a thread on the www.snowandmud.com online forum This report was posted by the CAC Forecast Manager, Karl Klassen. Be sure to follow the links within the report to learn more about the current state of our snowpack and to benefit from the recommendations offered by the CAC team of Forecasters. They have decades worth of experience.

Read each line…one at a time and let it sink in.

Remember that their passion is the snow, big lines and enjoying the backcountry just like us. The goal of an avalanche forecaster is to analyze and communicate actual observations and forecasted conditions in order to guide our choices. The point is to empower us to play SAFELY in the snow. The point is to minimize our exposure to obvious risk. Scaring us away from the backcountry is not their goal.

When the CAC issues special reports…take notice!

Avalanches are just like any serial killer. They usually follow a pattern. Become an avalanche ‘Crime Scene Investigator’ or CSI and learn more in order to better ‘profile’ these natural killers.

(Yeah, yeah….I watch the prime time crime shows whenever I get the chance!! I enjoy solving the puzzles.)

Never stop learning! You never know which tip or skill may make all the difference some day…..*

Understanding avalanche phenomena is a puzzle as well. Guess that’s why I find it so intriguing. Every year the blueprint is different. Every year we have different issues lurking in the snowpack. As the recipe in the snow changes so must our travel habits and terrain choices vary to accommodate any current instabilities.

By reading and actually taking the time to comprehend bulletins and reports, you will continue to upgrade and hone your avalanche interpretation skills.

CLICK HERE to download the Canadian Avalanche Centre’s update on the BC Avalanche Conditions

Did you hear that there was a Size 5 avalanche in the North Columbia region last week? Size 5…crazy!!
How big is a size 5? CLICK HERE to find out

Forecasters described the event in the Feb 16, 2011 CAC avalanche Bulletin as:

A large size 5 avalanche was reported yesterday in the North Columbia region. The fracture line being 600-700m long and approximately 8m deep. It was a storm triggered soft slab, which stepped down to ground on the November basal facet layer. It ran approximately 3000m in distance and destroyed 20 hectares of forest. The start zone is in a high, wind loaded alpine feature at 2600m on a south aspect.

Eight metre deep fracture line. Ran ~3km?!

Crazy, this doesn’t seem possible to rip a fracture line through that much snow….and it was a natural release! “Storm triggered soft slab which stepped down…”

(btw I asked around for photos of this massive slide….but no luck…if I ever get any I will be sure to post them here. Maybe it is like the Ogopogo.. ;-)

In many areas throughout Alberta and British Columbia avalanches have been releasing to the ground.

So now what?! How do we make responsible choices in a time period like this?

CLICK HERE to read the report submitted by Karl Klassen to the online Snowmobile and ATV forum www.snowandmud.com.

This means that the entire snowpack is sliding. Obviously there is a poor bond between the snowpack and the ground.

This is a picture of the type of sugary crystals responsible for the full snowpack avalanches. These are crystals from our backyard here in Alberta. The depth hoar crystals were formed early season, while the snowpack was shallow and the temperatures were cold. This process is called faceting.

These crystals grew and grew over time and added layer upon layer to their structures. Notice the striations in each of the crystals. Once formed, these dense, 3 dimensional crystals are quite resistant to change and often will persist for the remainder of the winter.

Go ahead…! Go check out the snow in your backyard. Dig deep and see if you find these sugary crystals.


Click a picture and send it in. Let’s compare! Who has the most dangerous yard!

Even terrain with anchors (trees and rocks breaking up the slope) do not necessarily add enough structure to hold some of these persistent weak layers on the hill.

If following the ‘trail over the hill to get to the next riding area’, your odds are better to stay on the highly traveled areas rather than sidehill and play along the way. Stick to the fat spots and avoid the shallow areas where you can tickle any weak layers that might be close to the surface.

When conditions are the problem, terrain is the solution.

Sounds good, but what does that really mean?

Being avalanche savvy really comes down to choices and timing.

Klassen’s report recommends avoiding:

Can you tell that I really want you to download the report!! Get ‘er done!

Thanks for reading. I hope that you found value in the material. Please add in your comments and questions. As well as your comments, consider forwarding photos that you may have as examples of avalanches, snowpacks, terrain or travel habits…good or bad!

Want to learn more?!

Gather up your riding group and arrange an AST1 or 2 class. Or even better, register for the 7 day Canadian Avalanche Associations ITP Level 1 (Industry Training Programs) Snowmobile Operations Course. The 2011 class was full and had a waiting list!

Be sure to sign up early! This professional level program is usually offered in late December or early January.


Glossary


These glossary terms originated on the CAC’s website: www.avalanche.ca CLICK HERE to view the full glossary
I couldn’t figure out how to link to the specific words on the CAC website…so I just reprinted them.

Size 5 Avalanches

Size 5 avalanches are the largest snow avalanches known. They could destroy a village or a forest area up to 40 hectares (~100 acres). They typically have:

* a mass of 100,000 tonnes * a path length of 3000 metres * an impact pressure of 100 kiloPascals

Text and diagram from “Advanced Avalanche Safety Course Manual” Copyright © 1998 Canadian Avalanche Association.

Stepped Down

A slab avalanche is said to step down if the motion of the initial slab causes lower layers to slide, resulting in a second bed surface deeper in the snowpack. A step in the bed surface is usually visible.

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Please Leave a Comment!

  1. thanks for the info. forwarded it to my 3 riding buddies, who have no training. if sense wont make them do it, hopefully this will scare them in to it.


    — Rod V    Feb 21, 03:40 PM    #

  2. Glad you found value in the newsletter!
    I think I’m working on a new angle to attract attention. I believe sledders need to become CSI’s (crime scene investigators).
    (According to my prime time TV channel!)...the job is a CSI is to gather information about the actions of all those involved, the characteristics about the scene and related locations. All of these facts, opinions and observations are used to profile the serial killer. Guess what…avalanche cycles can often be profiled!

    The CAC Public Avalanche Bulletin is basically the beginnings of a profile…built by an off-location CSI. Now it is our job to take this rough sketch of the killer and fill in the details to see if they have been active, or if there is a chance that they (the avalanche) may strike our riding area next!


    — Lori Z    Feb 21, 04:05 PM    #

  3. Lori
    The info was out there.
    Terrible that there are three more deaths
    Thx for all you do!


    — robert mackie    Feb 23, 08:49 PM    #
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