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Avalanche Forecast

Archived

Mar 22nd, 2020–Mar 23rd, 2020

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
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, human triggered possible.

Regions

South Rockies.

Cloud cover and flurries may temper daytime warming. Minimize exposure to cornices and continue to avoid thin, rocky start zones.

Confidence

High -

Weather Forecast

Sunday night: Increasing cloud. Moderate to strong southwest wind. Freezing level 1200 m.

Monday: Scattered flurries bringing trace. Moderate to strong southwest wind. Freezing level 1800 m.

Tuesday: 5-15 cm new snow. Light southwest wind. Freezing level 1000 m.

Wednesday: 5-10 cm new snow. Light southwest wind. Freezing level 1200 m.

Avalanche Summary

Loose wet avalanches were observed on solar aspects during the previous warm, sunny week. A single snowmobile triggered size 1 wind slab was observed amid extensive slope "testing" on Friday. In neighboring Waterton National Park, a size 2 deep persistent slab out of steep, thin, rocky alpine terrain Thursday reminds us that the basal facets still exist and can be triggered in this type of terrain. 

If you decide to travel in the backcountry, consider sharing your observations with us and fellow recreationists via the Mountain Information Network (MIN) to supplement our data stream as operators are shutting down. Even just a photo of what the day looked like would be helpful.

Snowpack Summary

A dusting of up to 10 cm of new snow sits over melt-freeze crusts on solar aspects, and extensively wind affected surfaces in exposed terrain that did not see the sun. Surface hoar was observed on these old surfaces before they were buried, mostly on shady aspects.

A layer of faceted grains overly a melt-freeze crust from early February. This layer currently sits 40 to 80 cm below the surface. 

The base of the snowpack contains basal facets that are most prominent in shallow, rocky start zones.

Terrain and Travel

  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

Problems

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.