Avalanche Forecast
Issued: Mar 19th, 2012 10:18AM
The alpine rating is Storm Slabs, Wind Slabs and Deep Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Intensity of incoming weather is uncertain on Tuesday
Weather Forecast
Monday overnight brings 8-15 cm of new snow. This is accompanied by strong South winds, and freezing levels near valley bottom. Tuesday: Snow amounts 15-25 cm. Ridgetop winds strong from the SW. Treeline temperatures near -5. Freezing levels near 500 m. Wednesday: Due to the convective weather pattern, scattered light-moderate snow accumulations are expected. Ridgetop winds moderate from the SW. Treeline temperatures near -8. Freezing levels valley bottom. Thursday: Cloudy in the morning, broken skies in the afternoon. Light afternoon flurries near 5 cm. Freezing levels valley bottom in the morning, rising to 700 m in the afternoon.
Avalanche Summary
Last week was very active with natural avalanche activity up to size 3.5. Additionally we had several reports of rider involvements and close calls. Some were failing on the mid-February persistent weakness. The size and frequency of avalanches seems to have decreased slightly over the weekend as storm slabs and wind slabs slowly gained some strength. On Sunday a skier accidently triggered a size 1.5 from a NE aspect, in steep rocky terrain. Avalanches were also triggered naturally and by explosives in steep, rocky terrain to size 2. Avalanche activity may increase with additional snow and wind on Tuesday. The danger ratings will rise.
Snowpack Summary
Last week, 100-180 cm storm snow fell, accompanied by strong south-easterly to south-westerly winds. Storm slabs and wind slabs now appear to be slowly gaining strength. Cornices are large and threaten slopes below. A persistent weakness, formed in mid-February, continues to produce hard, sudden planar results in snowpack tests. The likelihood of triggering this layer has gone down, but very large avalanches remain possible, which could be triggered by a shallower avalanche or cornice fall. The average snowpack depth at treeline is 350 cm. With the arrival of Tuesday's storm, new storm slabs and wind slabs will develop. It may take several days for the new storm snow to settle out and start to stabilize.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 20th, 2012 9:00AM