Escape the avalanche, collapsing and cracking snow are also known as alarm signals. Collapsing is when the pack collapses under you with a loud whumpf. Actually, whumpf has been adopted as a technical term to describe collapsing snow. As Alaska avalanche expert Jill Fredston says, “Whumpfing is the sound of Mother Nature screaming in your ear that the snowpack is unstable,” and if you experience a similar collapse on a slope that is steep enough to slide, know that it will not hesitate to do so.

Escape the avalanche, Collapsing, cracking snow

Snow collapses when your weight is enough to catastrophically collapse a buried weak layer, especially persistent weak layers. You can easily bring down avalanches from above in collapsing snow conditions. If a weak layer is already holding up the weight of a significant amount of snow, and the addition of the wimpy weight of just one person can collapse all the snow in a sometimes very large area, most people will intuitively recognize it as a very dangerous situation.

Whumpfing almost always elicits heart thumping and a wide eyed look of terror. Interestingly, seeing the scar of a recent avalanche does not produce the same response, yet it’s a much better indicator of danger.

Cracking snow is an obvious buzz from the avalanche rattlesnake.

Don’t take another step

Cracking is another warning buzz from the avalanche rattlesnake. It means don’t take another step; stop and take stock of your surroundings. Cracking snow means that all the ingredients for an avalanche are present: your weight is not only overloading a buried weak layer, but the snowpack can also propagate a crack (fracture). Once again, Mother Nature is hollering in your ear. Generally, the longer the crack, the worse it is. Stop. Poke around and see how well the slab is bonded to the underlying.

We often see cracking in fresh wind slabs, but it can occur with most other kinds of instabilities. I take students to small test slopes that have recently been wind loaded, like a 2-meter-high (10-foot-high) road cut, and let them jump on the wind slabs to get a feel for them. It’s an important skill to develop—recognizing wind slabs, knowing how they feel, knowing how they crack, recognizing that cracks mean danger.

Similar to cracking, hollow, drumlike sounds usually mean that you are standing on a slab (the drumskin) and there’s not much underneath. Wind slabs on top of soft snow usually sound hollow. Dig down and investigate, or jump on test slopes to test the sensitivity of the wind slab. Unlike cracking, hollow sounds do not always indicate danger, but you should definitely put on your avalanche goggles.