Avalanche Forecast
Issued: Mar 24th, 2014 9:41AM
The alpine rating is Storm Slabs and Deep Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Forecast snowfall amounts are uncertain on Tuesday
Weather Forecast
Overnight and Tuesday: A moderate to strong Southwest flow is expected to move moisture into the Southern coastal areas overnight. 5-10 cm of new snow above about 1500 metres combined with strong Southerly alpine winds. The system should move quickly inland bringing 5-10 cm to the mountain highway passes.Wednesday: Overcast with light precipitation and moderate Southerly winds. Freezing levels rising to about 1200 metres during the day and dropping down to about 500 metres overnight.Thursday: Overcast with light winds, flurries, and a chance of sunny breaks in the afternoon
Avalanche Summary
Some loose moist or wet snow avalanches were reported from steep Southerly aspects during periods of strong solar radiation on Sunday.
Snowpack Summary
Recent storm snow appears to be bonding well in the upper snow pack while increasing the load sitting on the persistent weak layers. The two persistent weak layers that remain a concern are:The March weak layer. A combination of hard wind-scoured slab surfaces in exposed terrain, facets and/or surface hoar in sheltered and north aspects, and sun crust on steep solar aspects and is generally widespread throughout the forecast region. This layer is now down between 70 and 80cm from the surface.A late January/early February crust/facet/surface hoar combo that is still showing up in snowpack tests with hard shear tests, now down 150 to 250cm from the surface. Recent warming temperatures will be good for bonding above and below this layer, but a sudden increase in load, a cornice failure, or a big rain event could "wake up" this layer and result in large avalanches. There are also basal facets at the bottom of the snowpack from cold clear weather in early December, but for the most part these have not been a concern, however, recently, a few large avalanches have stepped down to the basal facets and the ground.
Problems
Storm Slabs
Forecast new snow and strong winds are expected to develop new storm slabs. Watch for pockets of wind transported snow at higher elevations
Minimize exposure during periods of heavy loading from new snow, wind.>Use ridges or ribs to avoid pockets of wind loaded snow.>Extra caution needed around cornices with current conditions.>
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Deeply buried persistent weak layers continue to be a concern. Heavy loads like cornice falls or storm slabs in motion may trigger the PWL resulting in very large avalanches.
Give cornices a wide berth when travelling on or below ridges.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be aware of thin areas that may propogate to deeper instabilites.>
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 25th, 2014 2:00PM