Avalanche Forecast
Issued: Jan 12th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
Forecasters are uncertain about how deep persistent weak layers will react to the storm's heavy wind, rain, and snow inputs.
Uncertainty is best managed through conservative terrain choices at this time.
Summary
Confidence
Low
Avalanche Summary
No new avalanches were reported in the region since Wednesday. Backcountry users should expect to see evidence of a natural avalanche cycle from within the storm at all elevations.
Please continue to post your observations and photos to the Mountain Information Network. It helps strengthen our data gathering.
Snowpack Summary
10-20 cm of new snow and strong southerly winds are building reactive storm slabs in lees. New snow overlies previous wind-affected surfaces and possibly a sun melt-freeze crust on steep solar slopes.
In sheltered terrain, 40 to 70 cm of low-density snow sits over a crust formed in late December. This crust varies in thickness throughout the terrain and elevation. Uncertainty remains about the robustness of this crust above 2100 m. Storm slab avalanches could potentially step down to this layer, creating larger-than-expected avalanches.
There is a widespread layer of facets and depth hoar at the bottom of the snowpack. Uncertainty remains around the likelihood of triggering this layer. Snowpack depths around treeline are about 150 cm deep. The snowpack below treeline is very shallow and faceted.
Weather Summary
Thursday Night
Stormy, 15-20 mm of precipitation expected. Extreme southerly ridge winds gusting 80-100 km/h. A high of +1C at treeline. Freezing rain is possible on the Duffey Lake Road as freezing levels rise to 1800 m.
Friday
Stormy, 10-15 mm of precipitation. Extreme southerly ridge winds gusting 80-100 km/h. A high of +2C at treeline. Freezing levels hover around 1800-2000 m.
By evening the storm subsides easing winds and precip.
Saturday
Mostly cloudy with isolated flurries, 5 mm. Moderate southwesterly winds gusting 30-50 km/h. A high of -1C at treeline. freezing levels drop to 1500 m.
Sunday
A mix of sun and cloud. Light variable winds gusting 20 km/h. A high of -2C at treeline. Freezing levels continue dropping to 1200 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Minimize exposure during periods of heavy loading from new snow, wind or rain.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Closely monitor how the new snow is bonding to the crust.
Problems
Storm Slabs
By Friday morning 15-30 mm of precipitation has fallen at higher elevations as a mix of rain and snow. Where snow remained dry it has likely formed reactive storm slabs that are primed for human triggering.
Closely monitor the bonding of the new snow with the underlying surface. Be aware that slab avalanches could step down to deeper layers producing larger-than-expected avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
There are two weak layers within the snowpack that will be tested by the incoming storm and rising freezing levels. A crust found down 40 -70 cm has slowly been healing however in isolated areas weak crystals may surround this layer. Uncertainty remains about the robustness of this layer at higher elevations.
The lower snowpack is made up of facets and depth hoar. A large load or heavy rain may trigger deep layers resulting in very large avalanches.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Jan 13th, 2023 4:00PM
