Turnagain Pass

Wind Slabs: Yesterday Northeast winds on Sunburst weather station recorded sustained 30-40 mph winds with gusts in the mid 70’s mph. These strong Easterly ridge top winds combined with 8” of new snow have formed fresh wind slabs in the Alpine. There was also plenty of snow available for transport and these wind slabs have the potential to be 2-3’ thick on leeward features. Heavier warmer snow due to rising temperatures are likely to have made these slabs even more reactive. In many places in the alpine these wind slabs are resting on old hard wind crust from the wind event prior to this weekend’s storm. This combination was found in steep terrain in the upper elevations over the weekend where several skier triggered avalanche occured. Today it will be best to avoid loaded slopes steeper than 35 degrees. Feel for hollow feeling snow, stiffer snow over softer snow or slab sitting on hard snow and watch for cracks that shoot out from your snowmachine, skis or board. 

Storm slabs/Loose Snow avalanches: In places protected from yesterday’s winds storm slabs and loose snow avalanches are possible on steep terrain features. These are likely to be the top 8” of new snow. These are not likely to be large enough to bury a person, but could catch you by surprise. Avoid steep terrain traps where even a small storm slab or sluff could have high consiqences.  

Cornices are also expected to be tender today and could break off naturally or with the weight of a person or snow machine. If you find yourself along a ridge, give these unpredictable hazards extra space and avoid being directly beneath one. 

Roof avalanches: Heads up near building with loaded roof tops as warming temperatures today through Thursday will makes these unsupported slopes unstable. Many roofs have 2-3’ of heavy dense snow from the last few weeks, which is plenty of snow to bury a child, pet or seriously injury a kill an adult. 

A variety of persistant weak layers exist within the snowpack and vary across our region. In most cases these layers have been generally dormant. Incremental loading over the last four days has added stress to these older layers. In shallower parts of the area there are developed basal facets and in many locations there is a mid-pack layer of facets from December. At the lower elevations, below 2,000′, a layer of buried surface hoar exists under the last two snowfall events (1.5-2 feet below the surface). Slab avalanches failing on this layer are possible where the snow on top is stiff enough to form a slab. Warming temperatures today and through the next few days will make the slab more cohesive increasing the potential for a large more connected slab. The lower terrain in Placer Valley is an area that may have a similar set up. All of these layers are important to remember, especially if we receive a significant load in the next couple of days!!!

An example of the snowpack in the lower elevations at Tincan where a variety of weak layers remain the snowpack.