Avalanche Forecast

Archived

Feb 25th, 2023–Feb 26th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Tantalus, Sasquatch.

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.

Confidence

Moderate

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

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.