Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 3
Winds have been gusting close to or over 100 mph all night. Such strong winds in combination with new snow will continue to form both soft and hard slabs of wind-drifted snow on all aspects at the mid and upper elevations, and even low-elevation terrain features that allow for drifting snow to accumulate. As the winds continue to blow, these slabs will become more firm and more cohesive. This can allow you to travel out farther onto the slope before it breaks, and can fail larger and wider than expected.
Although the winds have been mainly from the west/northwest, sustained winds this strong can channel snow around terrain features and create fresh drifts on all aspects, including well-down off of ridge lines. You may even find fresh wind drifts at unusually low elevations below 8,000'. Remember, wind can deposit snow 10 times more rapidly than snow falling from the sky. The high winds over the last 24 hours are going to create strange and dangerous conditions. While there is some uncertainty attached to such sustained high winds, I expect the size and sensitivity of the wind drifts to have increased drastically since yesterday morning. I fear these conditions could catch someone off guard today.
What to do? Look for evidence of fresh drifted slopes, or wind slabs that look wavy, rounded, smooth, or pillow-shaped, and avoid travel on or below those slopes.
Any wind slab avalanche that you trigger has the potential to step down into deeper weak layers in the snowpack, creating a very large and dangerous avalanche.
