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Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
The freezing level should drop down to the valley bottoms overnight and then rise up to about 1500 metres during the day on Monday. This pattern is expected to continue for Tuesday and Wednesday. The only uncertainty is how much sun we will see over the next few days. There is a chance of valley cloud and high cloud each day.
Avalanche Summary
No new avalanches reported.
Snowpack Summary
I suspect that there was a good re-freeze down to valley bottoms that produced a new surface crust. In the Elk valley north there is 100-160 cm of snow at treeline. The late January crust and surface hoar is down about 30-50 cm and shows moderate results in snow profile tests; this layer was displaying very little propagation in tests. The mid-December buried crust layer is down about 50 cm at 2150 metres elevation and continues to react to hard forces in tests with stubborn results. The snowpack was moist down to the ground on Saturday, and is expected to re-freeze with forecast overnight temperatures. There is not much snow below 1600 metres, and a lot of bare areas below 1200 metres.
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.