Avalanche Forecast
Issued: Mar 20th, 2012 10:20AM
The alpine rating is Wind Slabs, Storm Slabs and Deep Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Wednesday: A few flurries. Light winds. Freezing level at valley bottom at night and around 1000m in the afternoon.Thursday: Light to moderate snow. Gusty winds. Freezing level is uncertain, but could rise to around 1600m.Friday: A mix of sun and cloud. Freezing level is uncertain, but could rise to around 1700m in the afternoon.
Avalanche Summary
On Tuesday, wind slabs in the size 1-1.5 range were triggered naturally and by skiers at treeline and above on slopes loaded by south-westerly winds. On Sunday, a size 1.5 avalanche released naturally on a north aspect. On Saturday, a recent avalanche was observed on a north aspect in the southern Elk Valley, suspected to have started as a wind slab and ending in moist snow. Evidence of a previous natural cycle was also reported. On Friday, explosives produced size 1-2 avalanches.
Snowpack Summary
Unsettled weather has brought snow and wind through most of the week, creating variable wind slabs and storm slabs. Newly formed 10-20cm thick wind slabs were easy to trigger on Tuesday at treeline and above. A melt-freeze crust buried below recent storm snow exists to 1900m on south aspects and 1700m elsewhere. An older rain crust is buried about 1m down. Two surface hoar layers, buried in February and now 1-2m deep, continue to exhibit sudden planar results, which have been repeated in a number of locations. This means these layers still have the potential to produce widely-propagating, destructive avalanches if triggered. Most likely triggering mechanisms are a person traveling on a thin snowpack area, or a storm slab, wind slab or cornice stepping down. Basal facets may still exist, particularly in shallow snowpack areas with steep, rocky start zones. Cornices have grown large and threaten slopes below.
Problems
Wind Slabs
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 21st, 2012 9:00AM