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Avalanche Forecast

Archived

Feb 14th, 2022–Feb 15th, 2022

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

Regions

North Columbia.

Manage open slopes at treeline carefully where triggering a persistent slab avalanche is most likely.

Avalanches are unlikely in areas where a hard surface crust is present.

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

A more unsettled weather pattern will bring a mix of sun and cloud and light snowfall throughout the week.

Monday Overnight: Cloudy with light snowfall. Freezing level dropping to valley bottom. Light to moderate northwesterly winds.

Tuesday: A mix of sun and cloud, light flurries. Freezing level rising to 1000 m. Light to moderate northwesterly winds. 

Wednesday: A mix of sun and cloud, light flurries. Freezing level rising to 1000 m. Light to moderate northwesterly winds. 

Thursday: Snowing. Freezing level rising to 1500m. Moderate to strong westerly winds. 

Avalanche Summary

Last week, near-daily reports came in of human-triggered persistent slab avalanches on the January 30th weak layer, with the associated surface hoar layer taking both recreationists and professionals by surprise. Reactivity has begun to taper but this buried weak layer should not be taken lightly as it may now present a low-probability, high-consequence problem. The most reactivity on this layer has been seen between 1600-2200 m in open areas in the trees, in cut blocks and on steep convexities. 

On Saturday, a large natural persistent slab avalanche occurred on a south-facing aspect in the alpine, potentially as a result of warm temperatures and strong solar radiation. On Friday in the South Colombia, large persistent slab avalanches were triggered with explosives on solar aspects in the alpine and treeline. 

Snowpack Summary

A light amount of snow is expected to bond poorly to the old surface. This surface is comprised of near-surface faceting and in some areas, surface hoar growth overlying a melt-freeze crust at lower elevations, a sun-crust on steep solar aspects, and hard wind-affected snow in the alpine and exposed treeline. 

Several weak layers exist in the upper snowpack including buried crusts, facets, and a prominent weak layer of buried surface hoar. This surface hoar has been the dominating feature in the past few weeks. It was buried in late January and exists 40 to 100 cm deep in the snowpack. The surface hoar is most prominent in sheltered openings at and below treeline.

The facet/crust layer that formed in early December is now buried around 120 to 250 cm. The last reported avalanche was on January 31 from a large explosive, and before that on January 23. Although unlikely, the layer could be triggered from a large load like a cornice fall or a shallower slab avalanche could step down to this layer. Humans are unlikely to trigger it, with perhaps the exception in thin, shallow snowpack areas. Check out the forecaster blog for more information.

Terrain and Travel

  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Be aware of the potential for large avalanches due to the presence of buried surface hoar.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.

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.