Avalanche Forecast

Archived

Feb 24th, 2024–Feb 25th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

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, human triggered possible.

Regions

Coquihalla, Harrison-Fraser, Manning, Skagit.

Avoid avalanche terrain

Natural avalanche activity is expected with heavy snowfall and strong winds.

Confidence

Moderate

Avalanche Summary

No recent avalanches have been reported.

Widespread natural avalanche activity is expected to begin on Sunday as snow and wind develop sensitive slabs.

Snowpack Summary

By Sunday evening, up to 60 cm of new snow is expected, falling over a variety of surfaces. Most concerning is the large surface hoar found in sheltered terrain, and a crust on south-facing slopes and all aspects below treeline. In exposed terrain at high elevations, new snows fall on old wind-affected snow.

A widespread crust is now buried 65-100 cm below the surface with weak, faceted snow immediately above it. Surface hoar was previously found above the crust in some parts of the region. Operators in the Hope area observed several whumpfs on this layer on shaded treeline slopes Thursday. Uncertainty exists over whether this layer will become active with the heavy load of new snow.

Weather Summary

Saturday Night

Cloudy with up to 20 cm of snow expected. 40-50 km/h southwest winds expected. Freezing levels remain around 1300 m.

Sunday

Cloudy heavy snowfall continuing, 20-40 cm of snow expected - heaviest in the southwest. 60 - 80 km/h southwest winds increasing over the day. Treeline temperature -3 °C with freezing levels around 1300 m.

Monday

Up to 20 cm of snowfall is possible overnight, again favoring the southwest. Snow tapers off on Monday morning with light flurries likely over the day.

Mostly cloudy with possible sunny breaks in the afternoon. Southwest winds ease, 30-40 km/h. Treeline temperature -5 °C with freezing level falling to 300 m.

Tuesday

A mix of sun and cloud with no snowfall expected. 30-40 km/h southwest winds. Freezing levels at valley bottom, treeline temperatures of -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Storm slabs in motion may step down to deeply buried weak layers resulting in very large avalanches.

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.