Avalanche Forecast
Issued: Apr 20th, 2018 4:02PM
The alpine rating is Wind Slabs and Cornices.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Friday night: Flurries bringing about 5 cm of new snow. Strong southwest winds.Saturday: Mainly cloudy with continuing flurries bringing about 5 cm of new snow. Strong west winds. Freezing level to 1600 metres with alpine high temperatures around -5.Sunday: A mix of sun and cloud. Light northwest winds. Freezing level to 1600 metres with alpine high temperatures around -6.Monday: Sunny. Moderate south winds. Freezing level rising to 2200 metres and climbing overnight. Alpine high temperatures around 0.
Avalanche Summary
Reports from Thursday included more evidence of the recent natural avalanche cycle described below, with several additional recent storm and wind slab releases to size 2.5 observed. Sun and wind were identified as prominent triggers.No new avalanches were reported in the Cariboos on Wednesday, but reports from the North Columbias 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 observed to have released on a large, wind-loaded alpine feature. Tuesday's reports included observations of several large (size 2) wind slabs that released naturally as a result of recent strong winds.Reports from Sunday and late last week showed a pattern of heightened cornice failure activity, with several cornice releases triggering large persistent slabs and wind slabs.Looking forward, continuing warm temperatures will be maintaining elevated chances of loose wet avalanche and cornice activity before another round of light snowfall introduces new surface instabilities over Friday night and Saturday.
Snowpack Summary
New snow is forecast to accumulate above a new melt freeze crust that can now be found on the surface on all but north aspects above about 2200 metres. Below it, about 50 cm of settled storm snow covers another supportive crust which shares similar distribution to the surface crust.Within this storm snow there are several different crusts with the shallowest of these (down about 25 cm) now a limited concern after warm temperatures have promoted settlement and bonding in the upper snowpack. Recent wind slabs on the surface at higher elevations are expected to be on a similar stabilizing trend.With warm daytime temperatures and poor overnight recovery of cold temperatures, there remains some lingering concern around reactivity at the mid-March persistent weak layer in the alpine where it is found 100 to 150 cm deep This buried crust/surface hoar layer may still be capable of producing large avalanches if triggered with a heavy load, such as a cornice collapse.Deeper persistent weak layers from December and January may be starting to become reactive to very large triggers. A recent cornice collapse is believe to have initiated a slab release on an early season layer, 300 cm deep.
Problems
Wind Slabs
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 21st, 2018 2:00PM