As we head into April, we continue to get reports of slab avalanche activity and other red flags associated with buried surface hoar and facets in the upper snowpack. This kind of activity is a clear indicator that the persistent weak layers that formed and were subsequently buried in March are still reactive, and still need to be considered when traveling in the mountains. These layers require patience and careful terrain selection, which means weighing the consequences of triggering an avalanche on the slope you are considering. For now, the snowpack is really not trustworthy and it is important to avoid steep slopes, especially those with terrain traps like rocks, cliffs, gullies, or trees, or avalanche paths with large, connected start zones. The most suspect slopes will be those that have a stiffer wind slab at or near the surface. Pay attention to clear indicators of instability like cracks shooting out from your snowmachine or skis, or the ‘whumpf’ of a collapse in the snowpack. The calendar may say that it is springtime, but the snowpack is still presenting us with all of the challenges of a mid-winter pack.
Wind slabs: Light to moderate winds overnight have likely created isolated wind-loaded pockets that may be sensitive to triggers today. Be on the lookout in the typical suspect terrain- below ridgelines, convexities, or in cross-loaded gullies.
Loose snow avalanches: Steep slopes that have been sheltered from the wind have around a foot of loose snow sitting on top of firm surfaces. It will be easy to trigger dry loose avalanches (sluffs) today, and they can pick up enough volume and speed to carry a person. If the sun stays out long enough, we will likely see some wet loose activity as well. While it is unlikely they will be big enough to bury you, they can be dangerous if they drag you into terrain traps like cliffs, trees, rocks, or gullies.
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