Avalanche Forecast
Issued: Feb 25th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Conditions are trickier than what meets the eye. A significant amount of new snow is expected to bond poorly to the underlying surface and may form reactive storm and wind slabs. What won't be as evident underfoot is the buried hard slabs from this week's northerly winds. Both of these problems are most likely to be an issue in wind-exposed alpine and treeline terrain.
Don't let good visibility and the desire to ride deep powder lure you into consequential terrain. Sheltered terrain will offer the best and safest riding.
Summary
Confidence
Avalanche Summary
Earlier in the week, numerous natural and human-triggered wind slabs (size 1-2) were reported throughout the region as strong northerly outflow winds redistributed surface snow and create stiff pockets of wind slab. These slabs occurred on a variety of aspects in the alpine all the way down to below treeline terrain.
Looking forward to Sunday, a more widespread storm slab problem may exist, particularly in areas that receive 25 cm or greater in the overnight period. Riders should take a cautious approach and be on the lookout for signs of instability such as whumpfing, shooting cracks, drumlike or hollow sounds, and recent avalanche activity. Keep in mind that older, stiff wind slabs may now be hidden under the storm snow.
For a deeper dive into this week's conditions, check out this awesome South Coast Conditions Report posted by Zenith Guides.
Snowpack Summary
Saturday night's storm will accumulate 15-30 cm of new snow down to valley bottom. This new snow is expected to bond poorly to the stiff wind slabs and near-surface facetting formed by recent wind and cold temperatures.
There are two crusts with facets sitting above, which are buried in the snowpack down 60-180cm in the alpine and treeline elevation bands. These crust/facet layers have been responsible for a few large avalanches in the past 2 weeks in the Brandywine and Pemberton Icefield areas.
The remainder of the mid and lower snowpack is well-settled, strong, and consolidated.
Weather Summary
Saturday night
Snowing, 15-30 cm of accumulation. Alpine temperatures around -10 °C. Ridge wind southwest 25-40 km/h. Freezing level at valley bottom.
Sunday
Cloudy with flurries and sunny periods. Alpine temperatures reach a high of -10 °C. Ridge wind southwest 20-35 km/h. Freezing level at valley bottom.
Monday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -9 °C. Light ridge wind from the south. Freezing level 900 metres.
Tuesday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -8 °C. Ridge wind light from the southwest. Freezing level at valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Good day to make conservative terrain choices.
- Dial back your terrain choices if you are seeing more than 30 cm of new snow.
- Choose low-angled, sheltered terrain where new snow hasn't been wind-affected.
- Be careful to keep storm day fever from luring you out into bigger terrain features.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Storm Slabs
In areas that receive 30 cm or greater in the overnight period, storm snow may settle into a widespread storm slab problem. Expect deeper, more reactive slabs to exist in wind-loaded terrain. Start with small, low-consequence terrain and assess the snow surface on any aspect you are travelling on for clues of instability, like cracking, whumpfing or hollow drum-like sounds.
Keep in mind that older, stiff wind slabs from previous northerly winds may still be reactive to human-triggering and are now hidden under the fresh storm snow.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Two weak layers consisting of a crust with small facets above buried between 50 and 180cm deep, have been responsible for a few large avalanches in the past two weeks. This problem seems to be more of an issue west of the Sea to Sky highway corridor. This layer is of greatest concern with large triggers, such as a cornice fall, or by first triggering a smaller avalanche that could step down to this interface.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 26th, 2023 4:00PM
