Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
Monday night’s storm buried some very weak layers under seven inches of low density snow. The weight of the new snow alone is not enough to overload our weak snow pack. You should be concerned about slopes where wind drifted snow has deposited a slab on top of the underlying weak snow. These slopes are stressed to just about their breaking point and the weight of a skier or rider may be all it takes to make them avalanche. In my travels yesterday I observed fresh drifts up to a foot deep on open slopes that have been cross loaded by up canyon winds, gullies that have been cross loaded, and just below ridge lines on leeward slopes. I also noticed fresh drifts mid slope on leeward terrain, maybe further down than you might expect. These slopes are especially worrisome because they can allow you to get further out on the slab before the weak layer fails. These are places where you might trigger an avalanche right now. SW winds will blow in the moderate range today and continue to deposit fresh drifts on leeward terrain.
The good news is wind drifted snow is easy to identify by its rounded, pillowy nature. Check out the photos below for some examples. There is also an obvious change in density when you step out onto a fresh drift. Cracks forming around your feet or shooting out in front of your skis are also signs that you have stepped onto a wind drift. Avoid fresh wind drifts today and you will avoid the avalanche problem.
The open slope in the photo below has been completely cross loaded by up canyon winds. Notice the pillowy nature of the snow across the entire slope.
The photo below shows another example of recent loading. Leeward slopes beneath ridge lines are loaded, but notice the slope down low that has also been freshly loaded