Turnagain Pass

An avalanche likely triggered remotely in the Placer valley yesterday. It is possible this avalanche failed on a buried weak layer at low to mid elevations. Otherwise, with low clouds and poor visibility we were not able to see recent avalanche activity. It is likely natural avalanches have released from this storm.

Human triggered avalanche that may have been remotely triggered at low to mid elevations in the Placer valley. Photo by Chris Yelverton 3.12.2024

This storm delivered nearly 2.5′ of new snow (2.5″ SWE) over the past 2 days in Turnagain with more in Placer valley, accompanied with overnight winds from the northeast gusting 50+ mph overnight. This will make it likely for a human to trigger an avalanche 2 to 3′ deep. With the rain line rising to 500′ this problem can be found at all elevations and slopes. Fresh wind slabs 1 to 3′ deep will be easy to trigger on wind loaded slopes and could release naturally. Red flags such as recent avalanches, blowing snow, firm snow over soft snow, cracking, and collapsing on small test slopes are all great indicators the snowpack is still being stressed and capable of avalanching. It is not recommended to travel on steep wind loaded slopes. If you decide to travel in avalanche terrain assess the snowpack cautiously and have a conservative mindset as you travel today. If you want to avoid these problems choose lower angle slopes and avoid runouts as larger avalanches can run further.

Loose Avalanches: It is likely to trigger a dry loose avalanche on steep northerly slopes. As the sun tries to show itself through the clouds today, wet loose avalanches may become a concern on steep southerly slopes, especially near trees and rocks. If the sunlight penetrates through the clouds, it has the potential to trap heat which can warm the snow faster than you would expect. Look for roller balls as indicators that the surface is capable of releasing a wet loose avalanche.

Cornices: Cornices likely grew immensely larger from strong winds and snow available to transport. Additionally, the snowpack warmed up yesterday and is expected to warm up today which will make easier for a cornice to release above you which can trigger a large avalanche.

John leading the hip deep skin track through 2.5′ of new snow on Tincan. Photo 3.12.2024

It is possible to trigger an avalanche 3 to 4ft deep on several weak layers that are being stressed by over 2.5ft of new snow. Our main concern is a weak layer of facets buried on March 5th at lower to mid elevations on all slopes. There are also reports of buried surface hoar at all elevations. We are uncertain how widespread and sensitive this layer is to being triggered. Yesterday, a natural avalanche was reported in the trees in Placer valley which is believed to have been remotely triggered. This is bullseye information telling us that a persistent problem is still an issue as remotely triggered avalanches can be triggered as you approach a slope and can release above or adjacent to you. Red flags such as cracking, collapsing, and whumphfing sounds are all indicators that the slope is capable of avalanching, however, there may be no evidence until an avalanche occurs.