Glide Slab & Crack Spring Safety from Ski Patrol

Over the past few weeks, our Ski Patrol teams have been noticing that significant glide cracks are appearing in frequently traveled areas across both Alpine and Palisades. These will be a safety hazard this spring, so we wanted to give you more information about what they are and how to avoid them. Oftentimes, these hazards cannot be seen at first, so you should be aware at all times that unmarked obstacles can exist on the mountain.

What is a glide crack?

A glide crack is a long crack or hole in the snowpack that can appear anywhere on the mountain. They are often found on steeper terrain next to rock features or on ridgelines where wind-deposited snow creates cornices. During warming weather, cornices on the leeward side of the ridge can pull away from the adjacent snowpack. This cohesive slab of snow is known as a glide slab, and it often consists of an entire snowpack that lacks enough friction on the surface beneath it to support it. These slabs “glide” slowly downslope as a whole unit, sliding over a smooth ground surface or sometimes a hard ice crust.

Glide cracks or slabs can be difficult to see, and new snowfall can bridge over the top of a crack, making them even more difficult to identify. Here are a few things to consider while you are out skiing:

Know the area you are skiing in and scope out your route before heading downhill.

If you are hiking and don’t have your skis or board on, you are much more likely to fall into a crack.

Ski and snowboard using the buddy system. Always stay within visual range of your partner.

Photo: A glide crack that is just starting to open up. These cracks increase in size as temperatures warm up. Taken by Justin Klein, Ski Patrol Director at Alpine.

What do I do if I fall into a glide crack? Or if I see someone fall into a glide crack?

Call Dispatch so that they can send Ski Patrol to help. You can find the phone numbers listed in the Palisades Tahoe App when you go to More > Emergency. Ski Patrol needs to know your location, how many people are involved, and the general situation, including how long the person has been in the crack and any pertinent medical information.

If you are in the crack, rapid movement and struggling will compact more snow around you and worsen your situation. Save your energy and stay calm.

Use your poles, skis, or board to stabilize yourself and prevent you from falling any deeper.

Try to exit the crack from the side, not directly from where you fell in.

You can also dig in your skis across the crack and use them as steps to get out.

What areas should I avoid? Cornices?

Yes, avoid cornices! Cornices can never be trusted and avoiding them is recommended. Cornices are unpredictable. They can release at any point and can break further back onto the ridge top than expected. Cornices can also release slab avalanches below when they fall. The weight of a mature cornice can be enough to penetrate many feet into the snowpack. Similarly, you should also avoid areas underneath cornices. Even a small cornice fall can injure someone. Periods of significant temperature warm-up are times to be particularly aware of cornice instability.

Are there other spring hazards I should be aware of?

As the weather warms, many of our creek beds may start to reemerge. Though you can’t tell in the wintertime, there are a large number of creeks that flow under our snowpack. When these begin to thaw, falling into them can be very dangerous. Always obey all closure signage to avoid ending up in an area where this might happen to you.