Avalanche danger is trending down after the recent warm and stormy weather. Some storm slabs at the higher elevations may continue to be reactive to human triggers.
Weather Forecast
Overnight: Freezing levels down to 1300 metres by morning, with moderate northwest winds and the chance of a few flurries. Sunday: Mix of sun and cloud with light westerly winds and some convective flurries during the day and 5-8 cm in the evening. Monday: Re-freeze down to near valley bottoms, followed by light winds and cloudy skies with a chance of convective flurries. Tuesday: Good freeze followed by clear skies and light winds.
Avalanche Summary
No new avalanches reported on Saturday. Numerous storm slab avalanches up to size 2.5 reported from explosives control on Friday, as well as loose wet avalanches released by ski cuts up to size 1.5. Numerous storm slab and loose wet avalanches were reported from the Fernie area on Thursday. One natural cornice fall was size 3.0, and pulled a storm slab from the slope below. There is concern for storm slabs to continue to be reactive to human triggering if there is little or no re-freeze before another warm day on Saturday.
Snowpack Summary
10cm of new snow is sitting on the newly developed March 31st melt-freeze crust. This crust has been reported to be knife hard and 5cm thick at higher elevations, tapering down to pencil hard and 3cm thick at 1200 metres. The earlier March crust is now down 40-100 cm. The December facets and November rain crust are buried deep, but they did not become reactive during the latest period of warm weather, rain, and strong solar radiation.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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.