Weather Forecast
A storm tracking along the international border will largely miss the Caribou region. The forecast calls for 2 - 4 cm Saturday and just a trace on Sunday. Freezing levels will remain at the surface through the forecast period and temps in the Alpine will average -9 C.
Avalanche Summary
Skiers and riders have triggered thin soft windslabs in the alpine up to size 1.0 . Natural ice fall and a natural cornice fall to size 2.5 were reported from the region. The cornice fall released a slab, but there was not much propagation.
Snowpack Summary
The new snow layer above the February 09 surface hoar is now about 10-15 cm thick. Some areas have reported that the surface hoar had grown to 50 mm before being buried. Some thin windslabs have developed due to down flowing air on large glaciated features. A melt-freeze crust has developed on solar aspects at all elevations, and on all aspects below about 1400 metres. The mid-pack is generally well settled. There is some concern that large loads like cornices may trigger the Jan. 20th facet layer. Some shallow snowpack areas may continue to have a weak layer of basal facets near the ground.
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.
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.