Regions
Northwest Inland.
Confidence
Fair - Due to limited field observations for the entire period
Weather Forecast
Wednesday: Isolated flurries with light southwesterly winds and freezing levels near valley bottoms. Thursday: 5-15cm (or more) possible with moderate to strong southerly winds and freezing levels as high as 1200m. Friday: Clearing and cooling trend throughout the day.
Avalanche Summary
Warm temperatures and light precipitation resulted in several low-elevation natural storm slab avalanches up to Size 2 on Monday. Some natural avalanche activity was observed in the Hankin area on Sunday on North and East aspects at treeline and alpine elevations. Slabs ranged in thickness from 20cm to 50cm and the avalanches were not running very far.
Snowpack Summary
Warm temperatures are promoting storm snow settlement and slab development at lower elevations. This recent storm snow is bonding poorly to faceted snow buried on January 20t , which is now down 45-80cm. Exposed alpine and treeline areas are wind-effected with big cornices and wind slabs on lee and cross-loaded slopes.
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.
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.