Avalanche Forecast
Issued: Jan 13th, 2015 8:30AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
rbuhler,
Avalanche Canada
Avalanche activity on the tricky mid-Dec weak layer has decreased recently but this layer should still be treated as a major hazard for the foreseeable future. Large and destructive human-triggered avalanches remain possible.
Summary
Confidence
Good
Weather Forecast
A ridge of high pressure will keep things dry for Wednesday and Thursday. A temperature inversion should keep the valleys cooler and under fog but above the fog should be mostly sunny. Alpine winds should remain light on Wednesday and Thursday morning but will progressively increase on Thursday afternoon. The next frontal system should reach the interior on Thursday night and is expected to yield 10-20cm. By Friday afternoon the system should be finished and some sun is expected. Alpine winds should be moderate-to-strong from the SW during the weak frontal system.
Avalanche Summary
No new avalanches have been reported since Saturday. On Saturday, a snowmobiler triggered a size 2 avalanche and was partially buried (YouTube video: https://www.youtube.com/watch?v=yhhAUcvXa3Q). This occurred in an opening at 1600m. It occurred on the mid-Dec weak layer down 40-50cm. Natural activity is generally not expected on Tuesday but remains possible in isolated areas, especially on sun exposed slopes. Human-triggered persistent slabs remain the main concern for the foreseeable future.
Snowpack Summary
The snow surface consists of surface hoar up to 10mm around treeline, a sun crust on steep sun exposed slopes, a localized thin breakable temperature crust, and/or wind affected surfaces in the alpine. Recent warm temperatures have aided in the settlement of the week old storm snow. The persistent slab is typically 40-70cm thick and sits on the mid-December surface hoar/crust layer which remains sensitive to human triggering. The reactivity of this persistent weak layer appears to be quite variable but still has the potential for large, destructive avalanches in some areas. The layer appears to be the most reactive at treeline or just below treeline.
Problems
Persistent Slabs
A persistent weakness buried mid-December is spotty in distribution and reactivity, but remains problematic at and just below treeline where the snowpack structure may still be primed for human triggering.
Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Use conservative route selection, stick to moderate angled terrain with low consequence.>
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 14th, 2015 2:00PM
