With the increasing interest in ski touring and splitboarding, recent years have also seen the unfortunate rise in avalanche-related deaths on slopes that should have been avoided. While an untouched powder slope might seem heaven-sent, unfortunately the results can be much more hellish if the conditions are ripe for an avalanche.
Since nature is unpredictable, you will never know 100% for sure if a slope is stable or not. But you can be more informed if the snowpack is “tight” or “loose”.
The easiest way to gauge this is by digging a snow pit and performing a compression test. This can be done in a few easy steps.
Tools: You will need several tools to perform this properly, which should already be in your bag. The three main tools you will need are a shovel, probe, and snow saw.
Here is a great video demonstration on how to complete a compression test. For step by step instructions, scroll down below:
Steps to performing a Compression Test:
Dig a trench or pit 60 centimeters (36 inches) wide by one meter (3 feet) deep. Skiers and boarders rarely impact weak layers deeper than about one meter and isolated columns higher than about one meter typically fall over.
Next cut the back of the column all the way to the floor of your pit so that you have a square column roughly 30 cm by 30 cm (12 inches ) square. Remember, all 4 sides must be cut and must be straight up and down on the plumb.
RESULTS: A weak layer within the column may fracture during any of the steps or there may not be any failure. The following index quantifies the results of your test. The acronyms in parentheses can be used to record results. They are from the Snow, Weather, and Avalanche Guidelines (SWAG) published by the American Avalanche Association and the Forest Service National Avalanche Center.
Very Easy: A weak layer fractures when you isolate the column. (CTV)
Easy: A weak layer fractures during your first 10 taps. (CT1-CT10)
Moderate: A weak layer fractures during your next 10 taps from the elbow (CT11-CT20)
Hard: A weak layer fractures during your taps from your shoulder (CT21-CT30)
No Fracture: Does not fracture (CTN)
SHEAR QUALITY: The fractures or shears defined above are divided into three types:
INTREPRETING RESULTS: Stability tests only test stability in the location the test is performed; consequently, it is important to perform several stability tests in several locations to get a more accurate test sample.
And a Quality 1 (Q1) shear is typically indicative of much more dangerous conditions than a Q2 shear and certainly a Q3 shear. Be warely of Q1 shears even when they require a moderate or hard force; Q1 shears indicate poor bonding and often very poor stability.Always be on the outlook for signs of instability; one sign of instability trumps all signs of stability. Stability tests are only one piece of the puzzle; conduct several of them in different locations and use them in conjunction with other observed clues and Red Flags when you make your assessment and decide whether to ski a slope or not.