Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3.5
Despite the beautiful days in the mountains currently, we are still wary of the buried weak layers in the Summit Lake region. These layers are slowly gaining strength, but are still capable of producing very large avalanches. We've been tracking several layers of faceted snow, These include one right at the bottom of the snowpack, multiple layers around melt/freeze crusts that formed during the series of warm storms in December and January, and some lingering surface hoar layers that also formed during the same time frame. These all exist within the lower 1 to 2 feet of the snowpack in most locations, and seem to be equally reactive (or stubborn, depending on how you look at it).
Several large avalanches broke on these weak layers during the previous two storm events, and it still seems the weight of a person might trigger a big avalanche in just the right spot today. It can be really hard to know for sure if this snowpack will make an avalanche on a specific slope. It is unlikely you will experience collapsing or cracking, and stability tests will likely give mixed results. Keep all of this in mind and consider waiting on the bigger objectives while the snowpack continues to heal.
Lingering Wind Slabs: Apart from the deep slab issue above, there are various wind slabs scattered about from the strong northwest outflow winds last week. As always, keep a look out for wind drifts and loading and any cracks that shoot out from you. Steering clear of wind slabs will be a good bet as they could be overlying a snowpack with weak layers.
Cornices: As anyone that has been out in the mountains after January’s stormy weather knows, the cornices are big. We can’t stress enough how important it is to give these an extra wide berth. They could be easier to trigger as warm temperatures are now being seen above 2,000’ and sunshine will add to this warmth during the midday hours. They are notorious for breaking back further than expected and it’s also a good idea to limit time under them.
Glide avalanches: Glide cracks are continuing to ooze open throughout the forecast areas. We are only aware of one that has released so far (south end of Seattle Ridge), but more cracks are appearing every day. These avalanches are very large and unpredictable. The best way to manage this problem is to avoid spending time under open glide cracks.
(2/1/2025)
Another beautiful day is on tap, but there are potentially dangerous weak layers lurking below the surface in the Summit Lake zone.
Photo: Spiritwalker in the distance. By Arnav