Avalanche Forecast

Archived

Jan 26th, 2012–Jan 27th, 2012

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.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Sea To Sky.

Confidence

Fair - Intensity of incoming weather is uncertain on Sunday

Weather Forecast

Friday: mix of sun and cloud and very light flurries / moderate northwest winds / freezing level at 600m Saturday: increasing cloud in the afternoon with snowfall developing later in the day / winds increasing to strong and southwest by the end of the day / freezing level at 700m Sunday: moderate to heavy snowfall / moderate southwest winds / freezing level climbing to 1100m

Avalanche Summary

Explosives control on Thursday produced mostly surface results to size 1.5. The exception was a size 3 slab that was 2.5 metres deep on a north facing alpine slope.

Snowpack Summary

Mother nature pummeled the Sea to Sky region over the last few days. Over 115cms of snow that fell since last weekend has now settled to about 80cm. 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. These interfaces have most likely gained considerable strength, but it is reasonable to believe that any avalanche activity could 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.