Deep Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 2–3.5
It has been 8 days since there was a very large avalanche on one of the buried weak layers we have been talking about for months now. This, combined with calm weather, means it is probably becoming more unlikely that a human would be able to trigger an avalanche on one of these layers. The problem is, we have some uncertainty, we don't know for sure the exact places where an avalanche could be triggered. This type of avalanche has a history of catching people off guard (multiple tracks on the slope before it releases), and the consequences would be devestating. We do know that these types of avalanches tend to get triggered from thin spots in the snowpack around rocky areas and places that have been scoured by the wind. We think this problem only exists in the alpine above 2,500' at this point so if you are heading up into that zone, safe travel protocols are essential. Choose low angle up routes and travel one at a time in steep terrain.
Lingering Wind Slabs: Old wind slabs can be found on many aspects from the strong winds last week. These should be stubborn to trigger at this point, but have been known to surprise people several days after a wind event. A shooting crack means the snow needs more time to stabilize. These wind slabs are in the same place as the deep slab problem described above.
Cornices: Temperatures remained warm overnight in the upper elevations. This, combined with the forecast sun today, will make higher chances for a natural or human triggered cornice fall. These are unlikley to trigger an avalanche below, but there is evidence of recent cornice fall in this zone and the chunks are big enough to do some damage if they hit us from above.
Glide avalanches: New glide cracks are being noticed daily in Turnagain Pass and a few are popping up in Summit Lake. It seems they were encouraged to wake up by the combination of the last big storm followed by a cold spell. The only one to release recently that we know of was sometime last week on the south end of Seattle Ridge. Two days ago, a group in Turnagain Pass was surprised to find themselves climbing up over a glide crack that they hadn't been able to see due to the steep slope. Avoid spending time under them if you can, the next one could release at any time.
(2/2/2025)
Large glide crack creeping on the south face of Manitoba.
Photo submitted anonymously