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Avalanche Forecast

Archived

Apr 4th, 2022–Apr 5th, 2022

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

Regions

South Columbia.

Up to 30 cm of storm snow has blanketed the region. Fresh storm slabs exist with deeper deposits on leeward slopes. If the sun pokes out expect avalanche activity to spike.

A conservative approach to terrain is a great way to ease into your day while assessing along the way.

Confidence

Moderate - Forecast precipitation (either snow or rain) amounts are uncertain. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Tuesday: New snow 5-10 cm at upper elevations. Moderate West wind at ridgetop and freezing level's 1500 m during the day and dropping to valley bottom overnight.

Wednesday: Chance of flurries and sunshine. Ridgetop winds moderate from the southwest and freezing levels rise to 1500 m.

Thursday: Mostly cloudy with some sunny periods. Trace snow amounts. Strong southwest wind and freezing levels rising to 2000 m. 

Avalanche Summary

A few isolated wind slabs up to size 1.5 were reported from our AvCan field team outside the ski hill boundary at RMR on Monday. No additional reports came in before 4 pm. The recent snow may have a poor bond to the underlying crust making rider-triggered storm and wind slab avalanches possible on Tuesday. 

Over the weekend (pre-storm) the region continued to see rider-triggered wind slabs up to size 1.5. Most of these failed on the end of March buried crust. 

On Saturday, a few natural dry loose to size 2 and many small wet loose avalanches were reported on steep sun-exposed slopes. Skiers triggered many small storm/wind slabs and dry loose that ran on the recent crust about 10-20 cm deep, as well as a dry loose of size 2. And explosives triggered a small storm slab.

Snowpack Summary

15 to 30 cm of storm snow has blanketed the region and buried multiple crusts in the upper snowpack. Moderate to strong west/ southwest wind will be redistributing the new storm snow in exposed high elevation terrain forming touchy wind slabs and developing large cornices.

The new snow brings 50-70 cm above will a crust from late March. The amount of snow on the crust tapers rapidly at lower elevations. This crust is present on all aspects up to an elevation of 2600 m. Below the crust, the snow is moist. 

The early-December rain crust is approximately a metre off the ground. Reports have recently indicated that large slab avalanches have failed on this interface earlier last week following a rain and warming event. This layer may be dormant now due to colder weather, however, it may appear again during the next big warm-up or with increased load from wind, snow and/or rain. 

Terrain and Travel

  • Watch for fresh storm slabs building throughout the day.
  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
  • Keep in mind the crust offers an excellent bed surface for avalanches.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.