Watch for fresh and reactive storm slabs forming Thursday as new snow arrives amid strong wind. Keep in mind the potential for triggering deeper slabs may persist even as natural activity from the previous storm tapers off.
40-80 cm of recent storm sits overtop a thick layer of weak, sugary facets. In the Monashees, this interface appears to be bonding well, while reactivity may persist longer in the Selkirks.
10-20 cm of new snow falls amid strong wind. Storm slabs will be most reactive where they sit over a sun crust and in wind deposited pockets in lee terrain features at upper elevations.
Cornices are experiencing rapid growth with strong west to southwest winds. Fresh, unsupported tabs that break off can act as triggers on slopes below.
Local enhancements in snowfall amounts possible in the Monashees and near Blue River.
WEDNESDAY NIGHT: Increasing cloud with flurries bringing up to 5 cm in most areas, strong southwest wind, freezing level valley bottom.
THURSDAY: 5-10 cm new snow in most areas, strong southwest ridgetop wind easing to moderate, freezing level 1100 m.
FRIDAY: 5-15 cm of new snow, light to moderate westerly wind, freezing level 800 m.
SATURDAY: A trace of new snow, light to moderate southwest wind, freezing level 800 m.
The Selkirks (eastern ranges of the region) were the hotspot for storm activity over the weekend and into Monday, with widespread natural wind and storm slab avalanches size 2-3 and explosive triggered size 3-4, many running to valley bottom.
Reports from the Monashees indicate a natural cycle to size 2.5 storm slabs peaking over the weekend and becoming more stubborn to human triggers as the storm tapered. Explosive work on Tuesday in the northern Monashees produced limited results including a few size 1's and and one size 2 cornice triggered storm slab.
We've had no reports of storm avalanche activity stepping down to deeper persistent layers.
10-15 cm of new snow is forecast to fall by the end of the day Thursday. It falls over 40-80 cm of recent storm snow which is well settled at lower elevations and heavily wind affected at upper elevations. Wind deposits up to 100 cm deep can be found in lee terrain features in the alpine and may remain reactive to human and machine triggers.
All of this recent snow sits over facetted surfaces from the cold snap. There is uncertainty around how long it will take for this interface to bond but reports from the Monashees have indicated a positive trend already.
We've now got 70 to 120 cm of snow above the late January persistent weak layer which is composed of surface hoar in openings in the trees and/ or a crust on steep solar aspects. An absence of step-downs to this layer in the most recent storm cycle indicate that is has likely healed.
