Avalanche Forecast
Issued: Jan 13th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Loose Dry.
Ian Jackson,
An avalanche cycle occurred on Wednesday with up to 40 cm of new snow, warm temperatures and strong west winds. Drier weather over the next few days will help things stabilize, but choose conservative terrain to asses the bond of the new snow.
Summary
Weather Forecast
Drier conditions over the next few days as a ridge builds. Temperatures will cool with lows near -10 to -15. Winds will switch to NW and decrease, but remain in the moderate range at the mountain top level.
Snowpack Summary
15-40 cm of warm snow over the last 24 hours with strong west winds has created touchy windslabs in exposed locations and storm slabs in sheltered areas. This sits on three persistent weak layers from Dec down 30-100 cm that are likely more reactive than before. The Nov. 5 basal crust/facets may also be more sensitive in thin snowpack areas.
Avalanche Summary
Avalanches to size 2.5 in the Field area including on Pilsner Pillar and the approach to Twisted and Silk Tassel. Ski hills reporting touchy storm slabs up to 50 cm deep in lee areas and still reactive but thinner in non wind affected areas. The bowl above Cascade falls ran naturally to size 3 at some point recently but already appears blown in.
Confidence
Due to the number of field observations
Problems
Storm Slabs
Warm temperatures, strong winds and 15-40 cm of new snow over the last 24 hours has created a storm slab that was touchy on Wed. Benign weather over the next few days will promote bonding, but there is a spotty weak layer buried under the new snow
- Use caution in lee areas. Recent wind loading have created wind slabs.
- Choose low angle and supported terrain. Avoid large features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Three persistent weak layers from Dec exist in the top 100cm of the snowpack. They continued to produced sudden results and had a couple of skier triggered avalanches on them in the past week. They are likely more sensitive following Wednesdays storm
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
- Be wary of slopes that did not previously avalanche.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Loose Dry
15-40 cm of recent snow will take a few days to settle out. It will sluff easily with any input (wind or climber/skiier) for a day or two.
- Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.
- Be cautious of sluffing in steep terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 14th, 2021 4:00PM
