Persistent slabs, resting on weak faceted snow near the crust buried on March 7th have been reactive on the northerly half of the compass above 8,000ft. Multiple, large human triggered avalanches were reported this week involving these buried layers. Some of these avalanches occurred in areas that slid during the early January cycle, so knowing the seasonal history of a slope can be helpful information when choosing terrain. Assessing the stability will be difficult without digging deep enough into the snowpack to assess old layers. Near ridge crests and on steep leeward slopes there is also a possibility for small wind slabs. These are identified by smooth pillows and loaded terrain features. Below 8,000ft avalanches are unlikely.An avalanche fatality in the south fork of Game Creek near Victor, ID occurred yesterday afternoon. Additional details will be made available as they are confirmed. Our heartfelt condolences go out to the friends and family of those involved.
Soft slabs have the potential to fail on buried facets deeper in the snowpack. These slides can have depths of two to four feet, propagate long distances, and may be remotely triggered from lower angle or adjacent terrain. Increased safety margins can help reduce uncertainty.
( Discussion is generated from the previous day's afternoon forecast. )Increasing clouds overnight and into tomorrow with a chance of light snow flurries during the day. In the mountains expect westerly winds averaging in the teens with temperatures rising to the twenties by mid-day.There are currently two avalanche problems, wind slabs involving the recent snowfall and persistent slabs involving deeper layers in the snowpack. Given the current significant spatial variability, determining where each problem is present is difficult. Wind slabs can be found near ridge crests and on steep wind loaded slopes. Persistent slabs exist where faceted snow is prevalent below the early March crust, it is most likely to be found on north facing slopes. Slab depths can vary and could be up to two feet thick for wind slabs and four feet thick for persistent slabs. Human triggered avalanches remain possible Friday and the avalanche danger will be Moderate in all forecast areas. Careful assessment of the snowpack is needed to identify areas of wind loading and areas where old weak snow is buried. Persistent slabs can break wider than expected and can also be triggered while adjacent to steep terrain.
