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Avalanche Forecast

Archived

Mar 8th, 2024–Mar 9th, 2024

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural avalanches possible, human triggered probable.
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 possible, human triggered probable.

Regions

Purcells, Dogtooth, East Purcell.

Danger may reach HIGH as mild temperatures and strong sunshine weaken the snowpack. Large natural avalanches may occur.

Choose small, low angle slopes free from overhead hazard.

Confidence

High

Avalanche Summary

Numerous very large natural and explosive-triggered persistent slab avalanches have been reported (size 2 to 3.5) this week. Natural activity appears to be tapering off, and while fewer human triggered avalanches have occurred in the last few days, reports indicate triggering is still very possible - as shown by this remotely triggered avalanche near Golden on Thursday.

The photos below show the type of terrain and typical size for these avalanches.

Snowpack Summary

Surface conditions currently include sun crusts on south facing slopes, lightly wind-affected snow, and settling snow.

A widespread crust that formed in early February is roughly 80-120 cm deep. Weak faceted crystals and surface hoar above this crust are contributing to large avalanches across the province.

Additionally, the lower snowpack is mostly made up of weak and faceted layers.

Weather Summary

Friday Night

Mostly clear skies. 20-40 km/h southwest ridgetop wind. Freezing level drops to valley bottom.

Saturday

Mostly clear skies. 30-50 km/h south ridgetop wind. Freezing levels rise to 1800 m by the afternoon. Treeline temperature -2 °C.

Sunday

Mostly cloudy with 1-5 cm of snow. 20-40 km/h south ridgetop wind. Freezing levels rise to 1500 m by the afternoon. Treeline temperature -4 °C.

Monday

Mostly cloudy. 10-20 km/h south ridgetop wind. Freezing levels rise to 1500 m by the afternoon. Treeline temperature -4 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Conservative terrain selection is critical, choose only well supported, low consequence lines.
  • Avoid being on or under sun exposed slopes.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.

Problems

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.

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.