We receive reports of avalanches almost daily, which has led to less confidence in the snowpack. The primary concern is the threat of superficial slabs stepping down to the deep, persistent weakness, which could result in full-depth avalanches.
Happy holidays, everyone!
Moderate to strong S and SW winds have built wind slabs in lee features in the alpine and down into treeline. These slabs are a concern where they sit over weak facets that could "step down" to the basal layers.
Weak facets and depth hoar associated with crusts near the base of the snowpack continue to produce slab avalanches 60-100 cm deep. Any area with a stiffer slab over the facetted lower snowpack can generate a larger avalanche that steps down to the ground.
There were no avalanche reports on Christmas Day, but it seems that wind slabs or deep, persistent avalanches are reported on most days. On the 24th, climbers triggered a small wind slab up on the Stanley headwall without incident. A natural size 3 avalanche was reported in the Grand Daddy couloir (likely triggered by cornice release), and Sunshine got a deeper release in the Delerium Dive with explosives.
15-20 cm of storm snow from the past week, combined with strong W/SW winds, has formed wind slabs in alpine lee areas which extend down into treeline.
The mid and lower snowpack is faceted and weak, with facet/crust interfaces near the ground. This is more pronounced east of the divide, while western regions display a deeper more settled snowpack.
Snowpack depths at tree-line are about 60 cm in eastern areas and 100 cm west of the divide.
On Boxing Day, expect trace amounts of snow, winds SW 20-40kmh in the alpine, and treeline temperatures ranging from -10 to -8C. No significant snow is expected in the next few days.
