Avalanche Forecast

Archived

Jan 25th, 2012–Jan 26th, 2012

Alpine

Natural and human triggered avalanches likely.

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 unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Sea To Sky.

Confidence

Fair - Due to variable snopack conditions

Weather Forecast

Thursday: Light snowfall in the morning with clearing expected by the afternoon. / winds moderate from the west / freezing level at surface Friday: mostly clear / light northwest winds / freezing level at surface Saturday: Mostly clear / light westerly winds / increasing cloud and rising freezing levels in the afternoon

Avalanche Summary

Explosive avalanche control have produced slab avalanches up to size 2.

Snowpack Summary

Mother nature has been pummeling the Sea to Sky region over the last few days. Over 100cms of snow that fell since last weekend has now settled to about 70cm. Recent southwest winds have consistently hovered in the strong to extreme category and wind drifts have been reported up to 3 metres high. The recent storm snow is resting on a variety of older snow surfaces. These surfaces include previous cold, dry low density snow which may have had seen some faceting, old wind slabs, and crusts. It is reasonable to think that any new avalanche activity may step down to any of these interfaces.Previous concerns about deeper persistent weak layers appear to have diminished. Snowpack depths at treeline are in the region of 260 cm.

Problems

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.

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.