Avalanche Forecast
Issued: Jan 2nd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
JSmith,
Avalanche Canada
New snow, wind, and rising Freezing levels have created widespread and reactive storm slabs. Large human triggered avalanches are LIKELY at all elevations on Sunday and very large avalanches on deeper weak layers are possible.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations. Forecast precipitation (either snow or rain) amounts are uncertain.
Weather Forecast
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SATURDAY NIGHT: Snow; 10-15 cm. / Strong, southwest ridgetop wind / alpine low temperature -4 / Freezing level 800 m.
SUNDAY: Flurries; 3-5 cm. / Moderate, west ridgetop wind / alpine high temperature -6 / Freezing level 1200 m.
MONDAY: Cloudy with isolated flurries; 0-3 cm. / Moderate, southwest ridgetop wind / alpine high temperature -8 / Freezing level 800 m.
TUESDAY: Mix of sun and cloud / Light, southwest ridgetop wind / alpine high temperature -7 / Freezing level 1000 m.
Avalanche Summary
On Saturday, a skier triggered a size 2 slab avalanche near the Gorge area. See the excellent MIN report Here.
Large human triggered storm slab avalanches are LIKELY at all elevations on Sunday.
Snowpack Summary
Up to 20 cm of new snow, moderate to strong winds, and rising freezing levels on Saturday have created widespread storm slabs ripe for human triggers.Â
Two persistent weak layers buried in early/mid Dec. are now 80 to 150 cm below the surface. The form and distribution of these layers are HIGHLY VARIABLE and have created conditions that can vary significantly from one valley to the next. The first layer down around a metre has been primarily reported as small surface hoar.Â
The next layer has been reported as a thin freezing rain crust, surface hoar, or thick rain crust depending on elevation and location. As a result, diligent investigation of the snowpack is required to get a handle on local conditions. Forecast snowfall for the weekend may reignite avalanche activity at these deeply buried interfaces.
Terrain and Travel
- Uncertainty is best managed through conservative terrain choices at this time.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Avoid traveling in runout zones. Avalanches have the potential to run to the valley floor.
Problems
Storm Slabs
New snow, strong winds and rising freezing levels have created widespread storm slabs ripe for human triggers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Two persistent weak layers buried in early/mid Dec. are now 80 to 150 cm below the surface. The form and distribution of these layers are HIGHLY VARIABLE and have created conditions that can vary significantly from one valley to the next .
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 3rd, 2021 4:00PM
