Regions
Northwest Coastal.
Confidence
Fair - Freezing levels are uncertain on Monday
Weather Forecast
Monday: Heavy snowfall from Sunday night will extend into Monday morning. Expect strong southerly winds and freezing levels up to 700m.Tuesday: Moderate snowfall arriving late in the day, becoming very heavy overnight. Winds expected to be strong from the south. Freezing levels will start out at surface rising to 1000m as the precipitation intensifies.Wednesday: Heavy snowfall. Strong southerly winds and freezing levels at 1050m.
Avalanche Summary
A few natural size 1-1.5 windslabs were observed in the last 24 hours near Stewart.A natural size 1.5 was observed below treeline near Terrace.
Snowpack Summary
A relentless pummelling by snow, strong to extreme winds, and fluctuating freezing levels over the past week has added around 130cm of new snow near Terrace and around 75cm near Stewart. Strong south to southwest winds have created hard and soft wind slabs on lee slopes. Large sensitive cornices also exist. A 2-day break in the weather this weekend may have helped to strengthen the recently fallen snow, but only marginally. Expect further significant wind slab and storm slab development with the forecast weather.In the mid snowpack, buried surface hoar and a crust-facet combo (which extends up to alpine elevations in the south and to 1000m in the north) have become less of a concern in the Terrace area as test results show that they have gained significant strength. Although the probability of reactivity on these layers has decreased, the nature of any avalanche on these layers would be deep and highly destructive.The lower snowpack is generally well settled and strong.
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.