Regions
Northwest Coastal.
The Avalanche Danger may change quickly in the spring. Even brief periods of sun or rain can trigger pushy loose wet avalanches or promote destructive cornice falls.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Wednesday
Weather Forecast
On Wednesday expect 5-12cm of new snow with strong southwest ridgetop winds. Continued light snowfall (5-8cm) and decreased winds are forecast for Thursday. Clearing skies are expected on Friday as a dry ridge of high pressure develops over the province. Freezing levels should hover between 1100 and 1200m for the forecast period.
Avalanche Summary
Loose wet avalanches to size 1.5 were reported to have occurred in steep terrain on a variety of aspects. They failed in response to periods of solar warming or rain. New wind slab activity is expected in response to new snow and strong winds on Wednesday.
Snowpack Summary
Light amounts of snow fell on Monday night. The new snow overlies older wind slabs in exposed terrain and settled powder on shaded, sheltered slopes. Spring conditions have continued to develop. With that, lower elevation and sun-exposed slopes will likely appear moist or refrozen. A layer of surface hoar or melt-freeze crust buried on March 3 is down 50-80cm and has been on the radar of professionals in the mountains north of Stewart. A more widespread crust/facet layer buried in early February can now be found down over a metre. Both of these deeper layers have become less likely to trigger, but have the potential for large avalanches especially with a large trigger such as a cornice fall. I'd be increasingly cautious during periods of warming or solar radiation.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.