Where loose snow or wind slabs overly a crust, it can provide an easy sliding surface for avalanches. Where a thick, supportive crust sits on the surface, avalanches are unlikely.
Wind is forecast to switch direction from southwest to northwest. Watch for wind slabs in lee terrain features. At treeline elevations, wind slabs may overly a crust which makes for an excellent sliding surface.
Sunday night: Mostly clear with isolated flurries in the early morning. Light to moderate northwest wind. Freezing level valley bottom.
Monday: Sunny. Light to moderate north wind. Alpine high -9 C. Freezing level valley bottom.
Tuesday: Mix of sun and cloud. Light northwest wind becoming strong at ridgetop. Alpine high -8 C. Freezing level valley bottom.
Wednesday: Mostly cloudy with isolated flurries. Moderate to strong northwest wind. Alpine high -5 C. Freezing level 600 m.
Small loose dry sluffs running on the rain crust were been observed in wind sheltered areas on Sunday. On Friday and Saturday, a widespread storm slab avalanche cycle was observed size 2-2.5 on all aspects above 1600 m.
Reports of deep persistent avalanches have been periodically coming in over the past few weeks, primarily from the western Boundary area but most recently on Saturday near Nelson. These large, deep avalanches are generally triggered by very large loads (cornice falls or vehicles) or from shallow, rocky snowpack areas.
Strong southwest wind during the storm has scoured windward aspects and formed loaded pockets in alpine lees. As high as 2000 m, the upper snowpack contains a series of crusts from recent warming and rain events.
A layer of surface hoar is buried 100-150 cm below the surface in sheltered areas around treeline but has not been associated with avalanche activity recently. Weak basal facet/crust layers are particularly noteworthy in the western Boundary area.
