Avalanche Forecast

Archived

Mar 6th, 2021–Mar 7th, 2021

Alpine

Natural avalanches unlikely, human triggered possible.

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 unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Lizard-Flathead.

In areas where the snow surface stayed dry during the heatwave, or there is a breakable crust present, triggering avalanches remains a possibility. In areas where the surface has frozen into a thick crust that supports your weight, avalanches are unlikely.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

SATURDAY NIGHT - Mainly cloudy with isolated flurries / moderate west wind / alpine low temperature near -6 / freezing level 1500 m and dropping to valley bottom

SUNDAY - Cloudy with sunny periods and a few flurries, up to 5 cm / moderate to strong southwest wind / alpine high temperature near -5 / freezing level 1500 m and dropping to valley bottom overnight

MONDAY - Sunny with cloudy periods / light west wind / alpine high temperature near -5 / freezing level 1500 m and dropping to valley bottom overnight

TUESDAY - A mix of sun and cloud / light southwest wind / alpine high temperature near -6 / freezing level 1500 m and dropping to valley bottom overnight

Avalanche Summary

There were no new avalanches reported on Saturday, at the time of publishing.

On Friday, there were a few reports of natural and human-triggered wet loose avalanches up to size 1.5, explosive triggered cornices up to size 2, and one explosive triggered size 2 persistent slab avalanche on a northeast aspect.

On Thursday, there were several reports of natural loose wet avalanches up to size 1.5 as well as natural and human-triggered wind and wet slab avalanches up to size 2. There were also a few reports of size 2.5 natural persistent slab avalanches in the nearby Waterton National Park region.

On Wednesday there were several reports of natural size 1 wet loose avalanches on solar aspects in the afternoon.

Snowpack Summary

Previous warm temperatures followed by a re-freeze created a crust on the surface in many areas, which has now been covered by a dusting of fresh snow. Dry snow may still be found on north aspects at upper elevations. Wind slabs are likely still present on northerly aspects in the alpine and at treeline.

Up to 50 cm of snow sits above a variety of old interfaces that formed in mid-February. There is 60-100 cm sitting on a persistent weak layer that was buried in late January. These interfaces are mostly made up of sugary facets, hard wind pressed snow, surface hoar in wind-sheltered locations, and sun crust on steep solar aspects.

Terrain and Travel

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Be aware of the potential for large avalanches due to the presence of a persistent slab.
Minimize your exposure time below cornices.
When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.