Avalanche Forecast

Archived

Mar 1st, 2014–Mar 2nd, 2014

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

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.

Regions

Glacier.

Loose, solar triggered avalanches are possible this afternoon on steep solar aspects. Minimize exposure to sun exposed slopes when solar radiation is strong.

Weather Forecast

A ridge of high pressure over the region gives one more day of sunny skies and cold temperatures. This AM strong ridge top winds are blowing from the N/E. Expect alpine temperatures around -18. An area of low pressure starts to move into the region tonight bringing snow. Flurries are forecast for Sunday, moderate snow is forecast for Monday.

Snowpack Summary

The Jan 28/Feb 10 PWL down 1-1.4m under a cohesive slab, is becoming more difficult to trigger but has high propagation propensity. Recently avy techs in the Bonney area had a whumph on this layer off the moraines and hard sudden planar results testing it at 2130m on a NE aspect. A surface sun crust has been found on steep solar aspects.

Avalanche Summary

We have observed solar triggered natural avalanche activity occurring from steep solar aspects, producing loose wet avalanches in the afternoon when the sun remains out. Numerous size 1.5-2.5 have been observed daily from steep southerly aspects along the highway corridor daily.

Confidence

Intensity of incoming weather systems is uncertain on Monday

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.

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.