Avalanche Forecast

Archived

Mar 19th, 2024–Mar 20th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Coquihalla, Harrison-Fraser, Manning, Skagit.

Continue to minimize your exposure to avalanche terrain and avoid overhead hazard until cooler weather arrives.

Human-triggered loose wet avalanches remain likely on steep solar slopes.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported on Monday. However, reports are limited.

Through the weekend wet avalanche activity was observed up to size 2.5. Steep rocky terrain and direct solar slopes are the most impacted. Avalanches observed did not step down to the buried weak layers.

Snowpack Summary

High freezing levels overnight will result in no refreeze or a weak re-freeze of the snow surface overnight. Where there is a re-freeze daytime heating will soften the crust making surfaces moist. As a result, the avalanche danger will rise rapidly throughout the day.

30 to 50 cm of moist snow overlies a variety of layers including a thin sun crust on south aspects.

Two weak layers of surface hoar, facets and a crust exist, buried 60 to 120 cm deep. While these have not produced recent avalanche activity concern remains about the possibility of step down avalanches.

Weather Summary

Tuesday Night

Partly cloudy. 20 to 40 km/h southwest ridgetop wind. Treeline temperature +1 °C with freezing levels falling from 2500 to 1700m by morning.

Wednesday

Mainly cloudy. 15 to 25 km/h southwest ridgetop wind. Treeline temperature +1 °C. Freezing levels fluctuate between 1700 and 2000m throughout the day.

Thursday

Cloudy with 1 to 8 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing levels rise from 1300 to 1800m.

Friday

Cloudy with 1 to 8 cm of snow. 10 to 30 km/h variable ridgetop wind. Treeline temperature -1 °C. Freezing levels rise 1500m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
Keep in mind that human triggering potential persists as natural avalanching tapers off.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Loose avalanches may start small but they can grow and push you into dangerous terrain.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.