Snowpits and Stability Tests...
Always watch for signs of instability; not for signs of stability.
If you perform a stability tests and it indicates stability is good; keep looking. If you perform a stability test and it indicates stability is poor; use great caution including staying on low angle slopes.
The more stability tests you perform the more apt you are to get an accurate stability assessment.
Interpreting snow pits and stability tests can be confusing; take a class and travel with experienced people to learn how to interpret pits and tests correctly.
Only assume a slope is stable once you have gathered a wide array of data including observations and performed several stability tests and none of your data indicates instability exists.
One sign of instability always trumps all other signs of stability.
Learn how to: Dig A Pit
Why Should I Dig a Pit?
Mother Nature often provides us RED FLAGS; however, sometimes the snow is unstable even when there are no obvious clues. So it is a good idea to routinely dig into the snowpack and examine whether it is likely to avalanche or not.
Where Should I Dig a Pit?
Picking out a place to dig a pit and do a stability test can be confusing. Naturally, the best place is the slope you hope to ski or ride; but that may be too dangerous so you may need to pick a representative slope. That slope should have the same:
- Snow depth
And, very importantly, your representative slope should be small enough that if it slides you likely will not get hurt.
Do I need to dig on a steep slope?
No. Always start by digging on a slope less than 30 degrees before entering steeper terrain. Recent research
has shown that you can conduct stability tests on slopes less than 30 degrees and find similar results as you would on steeper slopes as long as the snowpack is reasonably consistent.
Avoid digging in an area that is wind scoured, has old ski or board tracks, or excessive vegetation.
What Am I Looking For?
The Red Flags in your pit indicate snowpack may be unstable and slide. These clues include:
- More cohesive or harder, stronger snow over less cohesive or sofer, weaker snow. This is especially true when the weak snow is feathery or loose and sugary
- EASY stability test scores
- Clean, planar shears during stability tests
- Crack propagation in a weak layer
Stability Tests estimate the stability of the snowpack. Essentially, they gage how much force it takes to create a "mini-avalanche" on a "mini-slope." Check out the links below to see how to perform common Stability Tests.
Next Section: Compression Test »