Avalanche Forecast
Issued: Apr 19th, 2018 4:41PM
The alpine rating is Loose Wet, Cornices and Wind Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Moderate -
Weather Forecast
Friday: Mainly cloudy with isolated flurries and a trace of new snow, increasing overnight. Light south winds becoming strong at ridgetop. Freezing level to 1900 metres with alpine high temperatures around -2. Weak overnight cooling.Saturday: Cloudy with continuing flurries bringing about 5 cm of new snow. Light to moderate west winds. Freezing level to 1700 metres with alpine high temperatures around -3.Sunday: Mainly sunny. Light northwest winds. Freezing level to 1700 metres with alpine high temperatures around -4.
Avalanche Summary
Reports from Tuesday included observations of numerous natural wind slab release from size 1-2 on north through east aspects in the alpine. A skier triggered size 2 storm slab resulted in a near miss. Another recent very large (size 3.5) storm slab was also observed to have released on a large, wind-loaded alpine feature. Reports from Monday were limited by poor visibility but included one small (size 1, 20 cm deep) ski cut wind slab as well as skier-triggered loose snow releases on steeper slopes. The rough dividing line between loose wet and loose dry activity was about 2000 metres.In addition to heightened storm slab activity following regular snowfalls, observations from late last week also showed a pattern of heightened cornice failure activity. Reports of 'bus sized' blocks found in debris as well as a suspected cornice-triggered size 4 wind slab release should keep these looming giants top of mind.Looking forward, continuing warm temperatures will be maintaining elevated chances of loose wet avalanche and cornice activity before another round of snowfall introduces new surface instabilities over Friday night and Saturday.
Snowpack Summary
About 50-70 cm of rapidly settling storm snow overlies a supportive crust on all aspects to at least 2300 m (and possibly higher on south aspects).Within this storm snow there are a few different crusts with the shallowest of these (down about 2-40 cm) becoming a diminishing concern as recent warm temperatures have promoted settlement and bonding in the upper snowpack. Recently formed wind slabs on the surface at higher elevations are expected to be on a similar stabilizing track.With warm daytime temperatures and poor overnight recovery of cold temperatures, there remains some lingering concern around the mid-March persistent weak layer in the alpine where it is found 90 to 120 cm below the surface. This buried crust/surface hoar interface was widely reactive but is now likely trending towards dormancy. It should be kept in the back of our minds for its capability to produce large avalanches should it be triggered with a heavy load such as a cornice collapse.Deeper persistent weak layers from December and January are generally considered dormant at this time but may be starting to become reactive to large triggers, such as a cornice collapse.
Problems
Loose Wet
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 20th, 2018 2:00PM