In the south and western parts of the region, heavy snowfall is expected to continue and keep the avalanche danger at HIGH.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Monday: 5-10cm of new snow / Moderate westerly winds / Freezing level at 700mTuesday: 8-15cm of new snow / Moderate southerly winds / Freezing level at 400mWednesday: 7-15cm of new snow / Moderate southerly winds / Freezing level at 1000m
Avalanche Summary
An impressive natural storm slab avalanche cycle is expected to have occurred in response to new snow and wind on Monday. On Tuesday, natural avalanche activity is expected to continue, particularly in direct coastal areas where heavy snowfall is forecast to persist.
Snowpack Summary
The region has been pummeled by heavy snowfall and extreme southerly winds. By Monday morning expect about a metre of snow to have fallen in the past 48 hours. Thanks to the winds, I would anticipate extensive scouring and redistribution of the recent storm snow at all elevation bands with dense storm slabs lurking in lee and cross-loaded features. Impressive cornice growth is also expected to have occurred.About 150cm below the surface you'll find a crust that was buried mid-January and is present at all elevations. This crust is thin on northerly aspects and up to 3 cm thick on solar aspects. Most reports suggest an improving bond at this interface, but the load of the new snow may tip the balance and reactivate this layer in isolated terrain. Below this, the snowpack is generally strong and well-settled.
Problems
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.