Warm temperatures and sunny skies forecast for the next few days will have a significant weakening effect on the snowpack. If solar radiation is particularly strong, the avalanche danger could rise to HIGH.
Summary
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Tonight and Thursday: The South Coast will remain under a ridge of high pressure bringing dry and warm conditions. Freezing levels are expected to reach 3200 m by tomorrow afternoon, moderate NW winds and mainly clear skies. Friday: The whole Coast is under the high pressure system, clear skies, moderate W winds and freezing levels reaching record levels of 3300 m. Saturday: A frontal system is expected to reach the coast, expect cloudier skies, mild temperatures and winds tapering down.
Avalanche Summary
A skier triggered avalanche size 1 was reported on an E aspect.
Snowpack Summary
The main concern for the coming days is the unusual warming and solar radiation shock that the snowpack will take. This will weaken the snowpack and most likely increase natural avalanche activity on SE and S aspects, but also in shaded areas because of temperatures rising to plus 5 C in the alpine! As well as surface wet slabs and loose snow avalanches, there is the possibility of it stepping down to a deeper persistent weak layer (PWL) especially in the Northern part of the region. These PWLs are most problematic especially in shallower snowpack areas at treeline. Multiple avalanches just ran on the weak basal facet layer recently and whumphing (sudden settlement) were reported yesterday. An early January surface hoar is also buried under ~50 cm of the storm slab in sheltered areas at treeline and below treeline. In the southern part of the region, where the early season snowpack was deeper, these persistent weak layers do not seem to be as prevalent. However, temperatures and solar radiation will be even stronger in this part of the region, making wet slabs and loose avalanches even more probable.
slemieux,
Avalanche Canada
