Steer clear of freshly wind loaded features. Wind slabs are expected to remain reactive to human triggers.
Avoid thin and rocky start zones, especially in the alpine where deeply buried weak layers remain concerning.
Moderate winds and recent storm snow have built reactive slabs at higher elevations. Slabs may sit over a layer of surface hoar in sheltered terrain features, or over a sun crust on south facing slopes which may increase reactivity.
The base of the snowpack remains very weak. Very large human triggered avalanches are possible at higher elevations. Avoid shallow and rocky areas, where the snowpack varies rapidly from thick to thin.
The mid and lower snowpack also contain several surface hoar layers, most prominent in the Purcells. Due to the overall weak snowpack structure, small avalanches are likely to step down to any of these deeper weak layers creating large and destructive avalanches.
The storm produced avalanches up to size 3 from natural and rider triggers, and explosive control methods. Many avalanches have occurred within the storm snow or on the old snow surface, while some failed on the buried surface hoar layer.
Deep persistent slab avalanches continue to be periodically reported throughout the Purcells.
On Monday a naturally trigged size 2.5 avalanche stepped down to the basal facets on an east facing alpine slope.
This MIN post from Thursday observed a size 3 avalanche near Golden over 1 m deep.
Avalanche activity on this deeply buried weak layer is expected to continue as the snowpack structure remains weak and will be slow to gain strength. Similar activity may be occurring in the Rockies however we have less operators and observations coming from this area.
Up to 20 cm of low density recent storm snow sits over wind affected surfaces. Expect deeper deposits on north and east facing slopes, from southwest winds.
Buried surface hoar sits 30-50 cm deep in sheltered terrain features, and a thin sun crust exists at the same depth on steep south-facing terrain.
The lower snowpack contains a number of buried weak layers such as surface hoar with variable distribution, as well as a widespread layer of large, weak basal facets and depth hoar in some areas. These weaknesses have been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.
Tuesday Night
Mainly cloudy with isolated flurries. Light snowfall is expected in southern areas near Cranbrook. Light and variable winds. Freezing levels valley bottom.
Wednesday
Mix of sun and cloud. Light westerly wind. Alpine high of -8 °C. Freezing levels 500 m.
Thursday
A mix of sun and cloud with freezing levels rising to 1000 m. Alpine highs reach -3°C. Moderate to strong southwest winds. Light snowfall possible.
Friday
Mix of sun and cloud with moderate westerly winds. Freezing level around 500 m. Isolated flurries are possible.
More details can be found in the Mountain Weather Forecast.
