Although the likelihood of triggering a persistent slab avalanche is relatively low, the consequence of doing so is high. Continue to employ a conservative approach to terrain selection.
Weather Forecast
THURSDAY NIGHT: Clear skies, light northwest wind, treeline temperature -7 C, freezing level 500 m.FRIDAY: Mostly cloudy, light northwest wind, treeline temperature -6 C, freezing level 500 m.SATURDAY: Clear skies, light northeast wind, treeline temperature -4 C, freezing level 800 m.SUNDAY: Clear skies, light west wind, treeline temperature -3 C, freezing level 1100 m.
Avalanche Summary
There have been no reports of avalanche activity in the past few days.
Snowpack Summary
Between 5 and 15 cm of recent snow sits on a variety of surfaces, including wind-affected snow in exposed terrain at higher elevations, soft and faceted snow in shaded and sheltered areas, and a melt-freeze crust on steep southerly slopes.A layer of weak and sugary faceted grains sits on a melt-freeze crust about 60 to 110 cm deep. The layer is likely most prominent in the North Shore Mountains and on north aspects. This layer continues to be reactive in snowpack tests. The problem is not typical for the region and we expect this persistent weak layer to continue to linger.The lower snowpack is generally strong.
Problems
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.
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.