Ongoing periods of strong wind continue to develop reactive wind slabs in exposed terrain and two buried weak layers remain a concern for persistent slab avalanches. Give the snowpack time to recover from the recent warming and continue to use a conservative mindset.
Recent strong winds from the SW through NW have formed reactive wind slabs in exposed terrain at higher elevations.
Cornices may become weak with sun and warming.
The weekend warming has weakened cornices which are expected to remain weak on Monday.
The late-January crust/surface hoar/facets down 20-40 cm remains a concern. The mid-January crust/facet layer woke up in the neighbouring Lizard-Flathead region and may be a concern with the mild temperatures.
Freezing levels may stay elevated overnight and Monday morning but there is still a lot of uncertainty regarding the intensity and extent of any lingering warming.
Sunday Night: Mainly clear, moderate to strong SW wind, freezing levels 1500-2000 m with a temperature inversion.
Monday: Increasing cloud cover in the afternoon with a chance of flurries, moderate to strong SW wind, afternoon freezing levels around 1600 m.
Tuesday: Mainly sunny, light to moderate SW wind, freezing levels reaching around 1600 m.
Wednesday: Mainly sunny, light to moderate W wind, freezing levels climbing to around 2000 m.
This MIN report from Saturday describes a natural size 1.5 slab avalanche on a south aspect as well as shooting cracks and whumpfing while travelling. It also suggests the surface snow was getting warm and consolidating into a slab.
On Friday, four natural size 1.5 wind slabs were reported by the field team in this MIN post failing down 30 cm on a crust in cross-loaded terrain.
20-40 cm of rapidly settling snow now typically overlies the January 30 interface which consists of a melt-freeze crust to around 2000 m and on solar aspects extending into the alpine, surface hoar in wind-sheltered areas at and below treeline, and small facets in some areas. With the recent warming, the surface snow has settled into a cohesive slab over the weak layer and a new surface crust will likely form as temperatures drop.
Periods of strong wind over the weekend, mainly from the southwest through northwest, have formed reactive wind slabs in exposed terrain at higher elevations. Ongoing wind on Monday will likely continue to develop reactive wind slabs where there is still loose snow available for transport.
The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous very large avalanches in January but is now considered dormant. See this forecaster blog on how to manage this layer as it may come into play again later this season.
