Regions
Northwest Inland.
Periods of strong solar radiation combined with high daytime freezing levels may increase the chance of deep persistent avalanches.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Thursday
Weather Forecast
Overnight: Mostly cloudy with a chance of flurries and light northwest winds. Freezing down to valley bottoms by morning. Thursday: A weak ridge of high pressure should bring scattered cloud with periods of strong solar radiation, and daytime freezing levels up to 1200 metres. Friday: Cloudy with 3-5 cm of new snow combined with strong southwest winds and daytime freezing levels up to 1300 metres. Saturday: Another 3-5 cm of new snow and strong southwest winds.
Avalanche Summary
No new avalanches reported.
Snowpack Summary
Light snow combined with moderate southwest winds has developed wind slabs in the alpine and in some exposed treeline locations. Periods of sun and high daytime freezing levels have developed crusts below treeline and on sun exposed terrain at all elevations. The snow may be moist or wet below treeline during the warmest part of the day. The deep persistent weak layer of facets and/or a crust that were buried early in the winter are still lingering near the bottom of the snowpack.
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.