Danger ratings have decreased but concern still remains for deeper weak layers and lingering wind loaded features. Maintain your awareness as you travel.
Deep persistent slab problem are uncommon in the region. Good travel habits and conservative terrain choices are tools to manage this problem.
Northerly winds are expected to have developed wind slabs in the alpine and treeline. These slabs can be found on southerly aspects and may bond poorly to the underlying crust.
Weak crystals sit at the base the snowpack creating concern for large avalanches.
Whumpfing and cracking have been observed and human triggering should be considered possible on any steep slopes where snow becomes denser and forms a slab of cohesive snow - like wind affected slopes.
As northerly winds are expected to continue to redistribute snow, rider triggered wind slabs remain possible.
On Monday near Pemberton, a skier-triggered persistent slab avalanche occurred on a northwest aspect in the alpine. The bed surface of this avalanche was reported as a crust with large surface hoar above. Interestingly, this avalanche triggered a size 2 on a nearby slope, which failed on facets and depth hoar near the ground level. Settlements (a sign of instability) have been reported in shallow and rocky features where weak layers sit shallower and closer to the surface.
If you head out into the mountains, please share your photos or observations on the Mountain Information Network. Your information helps us understand local conditions!
In exposed terrain at higher elevations, pockets of wind slab sit in wind loaded features. Strong winds have pushed this snow into features lower on slopes than typically seen. Large surface hoar has been reported on the surface in sheltered areas, with a crust present on solar aspects.
A layer of weak surface hoar sits buried around 20-40 cm deep. The upper snowpack is generally low density and weak. The mid and lower snowpack consist of crusts and facet layers, with depth hoar observed near the ground, which is very weak and highly uncommon for this region. These layers are the primary concern for this area.
The snowpack is currently weak and shallow for mid December. In deeper areas, snowpack depths only reach 100-130 cm.
Friday Night
Increasing cloud. With light to moderate northwest winds. Freezing level below valley bottom.
Saturday
Mostly cloudy with 2 cm of snow possible. Moderate westerly winds continue. Freezing level below valley bottom. Alpine high of -10 °C.
Sunday
Around 5 cm of snow possible overnight. A mostly cloudy with a trace to 3 cm of snow possible. Light and variable winds. Temperatures drop further, with alpine highs of -20°C.
Monday
Mostly cloudy with moderate southwest winds. Freezing level below valley bottom. Alpine high of -20 °C. Isolated flurries possible.
SundayMore details can be found in the Mountain Weather Forecast.
