If alpine storm snow totals are less than 10cm, the alpine danger rating will likely be Moderate.
Confidence
Fair - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
FRIDAY NIGHT: 2 to 5mm of precipitation is possible, less than 10cm of total snow expected. Extreme SW winds.SATURDAY: Freezing level hovering around 1500m. 2 to 6mm precipitation resulting in 2 to 10cm of snow. Moderate SW winds at treeline, moderate to strong SW/W winds at ridge-top.SUNDAY: Freezing level starting at 1000m, rising to 1500m. Light W/SW winds treeline, Moderate W winds at ridge-top. Overcast. No significant precipitation expected.MONDAY: Freezing level hovering around 1500m. Light variable winds at treeline. Moderate SW winds at ridge-top. Overcast. No significant precipitation expected.
Avalanche Summary
In two separate incidents Thursday cornice fall triggered deep persistent slabs when it impacted slopes below. Both incidents were on north facing alpine features. Loose wet avalanches to size 2 were also observed from south through west facing terrain.
Snowpack Summary
The current surface consists of surface facets and surface hoar. Below this is the 10 to 45cm of snow that fell last weekend. This snow remains dry on high elevation polar aspects but has turned moist on east and west facing aspects and south facing features are moving into the spring corn cycle. Just below this snow you'll the supportive late-March crust that is thought to exist up to around 2100m. Moist snow underneath the late-March crust is ubiquitous in most of the region.Two significant persistent weak layers composed of crust and facets exist in the snowpack. Although they appear to have gone dormant for the time being, we will continue to monitor them closely. Mid-March is down 40 to 80cm below the surface and Mid-February is down 80 to 140cm. Observations indicate that there is significant faceting occurring between the two crusts. While an avalanche failing at either of these interfaces is unlikely, it may still be possible on steep unsupported alpine features.
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.