Mild temperatures provided for only minimal crust recovery overnight. The snow stability is continuing to hinge on the presence of a surface crust. Radiant overnight cooling has formed a new surface crust each night this week, only to be rapidly destroyed by the combined effects of the sun and mild temperatures each day resulting in a diurnal swing in avalanche danger levels.
The snowpack is generally very weak and isothermal. Avoid traveling across or under any steep mushy non-supportive slopes. Large destructive cornice failures are a constant threat at this time of year. Give them a wide berth from above as well as from below.
The extended outlook is calling for the ridge of high pressure that has been parked offshore to continue to dominate our weather this week, with a continued Northerly flow down the coast of BC. The coastal air mass is however forecasted to remain somewhat unstable with a continued threat of afternoon thundershowers throughout the week triggered by daytime heating.
Any cloud cover that may form later this week could prevent the escape of heat from the snowpack. This would become even more pronounced with any additional heat introduced into the snow by any rainfall. Backcountry travel should be avoided if these conditions materialize.
The backcountry avalanche danger is rated as LOW, increasing throughout the day with exposure to sun and rising temperature,
Whistler Mtn. Snow Safety
