Avalanche Forecast
Issued: Dec 20th, 2015 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
tim haggarty,
Avalanche Canada
Windslabs continue to develop in the alpine. Concern remains for the Dec 3rd persistent weak layer, dig frequently to check for presence of this spotty surface hoar problem and keep a watchful eye on the character of the slab above it. TH
Summary
Weather Forecast
Westerly flow will bring light amounts of precip under mainly cloudy skies with light to moderate alpine winds over the forecast period. Expect 10cm total through Wenesday. Temps will drop a bit from highs near -10 to as low as -25 at treeline overnight Monday corresponding with some clearing and diminished winds that evening.
Snowpack Summary
10 cm of recent snow has added to the faceted slab over the Dec 3 Surface Hoar now 30 to 50cm deep. While significant shears persist on this layer in isolated, shaded and sheltered areas from 1500 to 1800m, the slab above it continues to lose strength. Meanwhile moderate SW winds are steady building slabs behind prominent features in the alpine
Avalanche Summary
Reports citing windslabs up to size 2 in the alpine sensitive to skier traffic have come in over the last 24 hrs as well as a few natural cornice events. Small loose dry activity has also been seen at treeline and above, while these are of minimal consequence at this time in all but extreme terrain, their size is likely to increase.
Confidence
Problems
Wind Slabs
New isolated slabs soft slabs are steadily growing in alpine terrain. These fresh slabs are easily triggered by skiers and will be found in the immediate lee sides of prominent features. Fragile recent cornice growth has also been failing naturally.
- Use caution in lee areas. Recent wind loading has created wind slabs.
- Use safe ski cutting techniques before entering ski run.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood
Expected Size
Persistent Slabs
The slab above this layer has facetted out in many areas which has lead to a decrease in triggering however tests continue to produce significant shears. Be cautious in aggressive terrain or in wind affected areas where the slab may retain strength.
- Avoid unsupported slopes.
- Dig down to find and test weak layers before committing to a line.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 21st, 2015 4:00PM
