Persistent weaknesses are present and active in the northern bulletin region, like the slack-country off Marmot Basin Ski Hill, Portal Creek, and the Tonquin.
Weather Forecast
Gusty North winds expected to persist overnight and through the day Sunday. Temperatures will continue to drop with overnight temperatures to -27, and Sunday's daytime high near -23 for the whole bulletin region.
Snowpack Summary
Available snow has been redistributed by strong, variable direction winds. At all elevations, where transported, new wind slabs will be sensitive to triggering. A persistent slab, down 50 to 80cm, is prevalent through the forecast region. Any large TL avalanche terrain that has not obviously avalanched should be expertly managed or, avoided.
Avalanche Summary
No new avalanche activity observed or reported.
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.