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Avalanche Forecast

Archived

Feb 25th, 2014–Feb 26th, 2014

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

Regions

South Rockies.

Don't let the good weather lure you into high risk scenarios. Conditions remain tricky.With clear, sunny skies the avalanche danger can rise quickly.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Wednesday

Weather Forecast

The arctic ridge of high pressure that has been dominating the Interior Regions will start to retreat on Wednesday, bringing warmer alpine temperatures and slightly rising freezing levels. Some disturbances in this flow will bring cloudy skies and light snow later in the forecast period.Wednesday: Sunny and -2.0 degrees expected in the alpine. Ridgetop winds will be light from the NW. Thursday: Cloudy with light snow and -1.0 degrees in the alpine. Ridgetop winds 25 km/hr from the NW. Freezing levels near 1800 m.Friday: Cloudy with isolated flurries. Alpine temperatures -19.0 and ridgetop winds will be light from the NE.

Avalanche Summary

A few loose dry avalanches from steeper terrain were reported on Tuesday. On Saturday, we received a report of a size 3 snowmobile triggered avalanche in the Coal Creek area (Notch). To our knowledge, there were 7 people involved and all were self rescued. The avalanche was on a North aspect and the crown depth was 1-2 m deep. Conditions remain ripe for human triggers.Natural avalanche activity, especially on steep solar aspects  will likely spike with full sunshine during the forecast period.Check out the South Rockies Blog for recent photos and insights of what people are seeing out there.

Snowpack Summary

Large cornices loom on ridgelines and threaten the slopes below. Variable winds have transported some of the recent storm snow, building new wind slabs on leeward slopes. A persistent slab 80-120 cm thick sits on a weak interface comprising of facets and a crust. It continues to show sudden planar shears at the interface, and a high degree of sensitivity to rider triggers. Wide propagations and remote triggering remain a concern. With forecast sunny periods, solar aspects may see moist snow surfaces which will then form a crust overnight. The deep persistent layer of facets and depth hoar near the base of the snowpack has remained dormant to this point, but may become a concern with additional load and stress on the snowpack like a cornice fall or large avalanche.

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.

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.