Avalanche Forecast
Issued: Feb 17th, 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.
llarson,
Avalanche Canada
More snow, more wind. There is plenty of snow available for transport and variable winds in the forecast building touchy storm slabs and wind slabs. Conservative terrain choices are your best bet for the weekend.
Summary
Confidence
Avalanche Summary
Several loose dry during the storm on Thursday. Touchy storm slabs up to size 1 as the storm amounts accumulated through the day
Looking forward, storm slabs will be reactive to human triggering and touchy at upper elevations where the new snow is being redistributed by variable winds.
The lower snowpack is slowly gaining strength, new snow and wind-driven snow, forming storm and wind slabs triggered by large loads like a cornice or machine may step down to these deeper weak layers. Continue to manage this problem by avoiding terrain that is steep, rocky, and shallow.
Snowpack Summary
Variable snowfall amounts across the region with Pine Pass, Core Lodge riding area, and the southwest receiving the highest amounts.
New snow and moderate to strong southwest winds have developed wind slabs at all elevations. These new wind slabs are developing over various surfaces of stiff old wind slabs in open terrain, soft snow in sheltered locations, and a melt-freeze crust below 1200 m and on steep south aspects. Cornices are becoming overhanging and reactive, and new snow and wind will further develop their growth.
The mid-pack is gaining strength and consists of rounding facets and melt-freeze crusts that are starting to degrade. A spotty surface hoar layer buried around January 4th can still be found between 60 to 80 cm. Avalanche activity has not been reported on this layer recently but it is still showing up in snowpack tests.
Near the base of the snowpack, a persistent weak layer composed of large and weak facets formed in November is strengthening slowly. This layer is most likely to be triggered in thin, rocky alpine and upper treeline terrain.
Weather Summary
Friday night
Cloudy with flurries, increasing snowfall overnight accumulation 15 to 20 cm, 30 to 40 km/h southwest winds switching to the northwest, treeline temperatures -10 °C.
Saturday
Cloudy with flurries easing in the afternoon, then picking up again overnight, highest amounts in the southwest of the region, accumulation 5 to 10 cm, 30 to 40 km/h northwest winds, treeline temperatures -10 °C.
Sunday
Cloudy with snowfall, accumulations of 10 to 15 cm, west winds 40 to 50 km/h, treeline temperatures -10 °C.
Monday
Mix sun and clouds, trace accumulations, 5 to 10 km/h winds, treeline temperatures -10 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid exposure to slopes that have cornices overhead.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Storm Slabs
An additional 15 to 20 cm of new snow will bring weekly totals to 40 to 60 cm. Winds during the week have been redistributing snow into lee features at all elevations and will continue with this new weather system bringing more new snow coupled with variable winds. Wind slabs will likely develop at upper elevations and on all aspects due to variable winds.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large, weak facets sits near the base of the snowpack. This layer is most prominent in the upper treeline and lower alpine elevations. This layer may be triggered by large loads like a wind slab avalanche that steps down to deeper layers or a cornice release.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 18th, 2023 4:00PM
