New wind slabs are expected to develop on Sunday afternoon. The Avalanche Danger may increase throughout the day.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
A series of weak systems will pass through the region over the forecast period. Expect 5-10cm of new snow on Sunday afternoon, a mix of sun and cloud on Monday and an additional 5-10cm of snow on Tuesday. Ridgetop winds will be extreme from the southwest on Sunday afternoon, strong and northwesterly on Monday, and strong and southwesterly on Tuesday. Freezing levels should hover around 1500m for the forecast period.
Avalanche Summary
No new avalanches were reported on Friday; however, observations were limited. Increasing winds and light amounts of new snow will spark a new round of wind slab activity in higher elevation lee terrain.
Snowpack Summary
A supportive crust (in most places aside from shaded aspects at treeline elevations) and perhaps new surface hoar (where it survived the heat, rain and sun) could be buried by as much as 10-15cm of fresh snow or deeper wind slabs. Avalanche professionals are still monitoring three buried surface hoar layers in the upper 150 cm, with recent reports of hard, but still sudden snowpack test results down around 120cm and 140-170cm.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.