Regions
Northwest Inland.
Most slabs avalanches in the past week have been triggered by cornices. Be cautious in wind affected terrain.
Confidence
Moderate - Due to the number and quality of field observations
Weather Forecast
FRIDAY: Cloudy with isolated flurries, strong southeast wind, freezing level up to 1500 m after an overnight freeze.SATURDAY: 5-10 cm of new snow, light southeast wind, freezing level around 1400 m.SUNDAY: Mostly cloudy, moderate south wind, freezing level around 1300 m.
Avalanche Summary
Several thin wind slabs were reported in northerly terrain in the Howsons on Wednesday. A few cornice triggered slabs have been reported throughout the region over the past week (up to size 2.5).
Snowpack Summary
Strong winds with light amounts of snow formed fresh wind slabs in exposed terrain on Wednesday. Elevations below about 1300 m are experiencing a daily melt-freeze cycle. Hard crusts form overnight and become moist during the heat of the day. Hard crusts may be found at higher elevations, particularly on slopes that were sun-exposed. The February crust and facet layer is 70-90 cm deep in the Houston Telkwas sled area and a deep persistent faceted weak layer is still lingering near the bottom of the snowpack in all areas.
Problems
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.
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.