Regions
Northwest Coastal.
Watch for changing snow conditions when the sun comes out. Storm slabs and persistent slabs are possible at higher elevations.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
MONDAY: Sunny skies, light winds, and freezing level rising to 1000 m after an overnight freeze.TUESDAY: Overcast with light snow starting in the afternoon, increasing south wind, and freezing level climbing to 1200 m. WEDNESDAY: 10-20 cm with strong south wind and freezing level around 1200 m.
Avalanche Summary
On Saturday, a few explosive and natural triggered storm slabs were reported in the Stewart / Bear Pass area. Most storm slabs were size 1.5 in the top 20 cm of snow, with some larger natural storms slabs in big alpine features around Bear Pass. On Friday, one loose wet avalanche size 1 released from a ski cut below treeline in the Shames area.More storm slab activity likely occurred on Sunday, and storm slabs may remain reactive to human triggers on Monday.
Snowpack Summary
20-30 cm of recent storm snow is settling at higher elevations. Warm daytime temperatures and sun are creating moist snow at treeline and wet snow below treeline, with reports of 40-60 cm of moist snow at 1200 m around Shames. The late February persistent weak layer continues to be a concern for triggering large avalanches. This combination of crust and weak facets is now down 100-150 cm, and may be triggered by light loads in shallow weak spots. The snow below treeline may become weak and release as loose wet avalanches or wet slabs in steep unsupported terrain features.
Problems
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.
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.