Avalanche Forecast
Issued: Dec 21st, 2016 5:19PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
jfloyer,
Avalanche Canada
Mostly a wind slab problem, but as the upper snowpack settles, things might start to change. If you see signs of instability, like whumpfs (rapid settlements), or see small rolls peel off, avoid unsupported (convex) terrain features.
Summary
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Thursday: Dry with some sunshine. Ridgetop winds 60-80 km/h from the southwest. Freezing level rising briefly to around 1600 m. Friday: Flurries. Winds southwesterly 40-60 km/h in the morning, diminishing to 10-20 km/h by the afternoon. Freezing level at valley bottom. Saturday: Light snow with 1 to 3 cm accumulation. Winds light northeasterly. Treeline temperatures around -9C.
Avalanche Summary
In recent days, explosives and human-triggered wind slab avalanches have occurred to size 2. In the southeast corner of the region, a few explosive-triggered avalanches have stepped down to deeper faceted layers producing persistent slab avalanches in the size 2.5-3 range. Looking forward, continued extreme southwest winds are expected to promote ongoing wind slab activity. There is a bit of uncertainty regarding how the new snow will bond to old surfaces which formed during last week's cold snap. Due to these potentially persistent weak layers, recently formed wind slabs may remain sensitive to human triggering for some time.
Snowpack Summary
Since Sunday night, 15-40cm of new snow has fallen. In exposed terrain, strong to extreme winds have redistributed much of this snow into fresh wind slabs. The new snow buries a variable surface that developed over the last week of cold, dry, and windy conditions. This interface consists of scoured surfaces and wind slabs in wind exposed terrain, widespread faceting of the upper snowpack, and surface hoar up to 20 mm in sheltered areas. In sheltered areas, there may be another layer of surface hoar in the upper snowpack which was buried around December 10. Observations have been limited, however, the reports we've received suggest the mid and lower snowpack are somewhat unconsolidated and faceting exists to varying degrees.Below treeline, the snowpack is very shallow and early season hazards such as stumps, rocks, and open creeks are still a major concern.
Problems
Wind Slabs
Wind and warming have added cohesion to the recent storm snow, and wind slabs may be ripe for triggering. In some cases, wind slabs have stepped down to deeper, more destructive layers. Use extra caution in steeper, wind-exposed terrain.
Be alert to conditions that change with elevation.Avoid freshly wind loaded features.Avoid slopes where the snow feels stiff or slabby.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 22nd, 2016 2:00PM
