Regions
Northwest Coastal.
The snowpack is tricky to predict at the moment. Backcountry travel requires local knowledge, extensive experience and training. Please read the new Forecaster's Blog Post.
Confidence
Fair - Intensity of incoming weather is uncertain on Friday
Weather Forecast
Friday: The approaching warm front brings moderate snow amounts near 10 cm. Ridgetop winds 30-50km/hr from the West. Treeline temperatures -8. Freezing levels could rise to 600 m. Saturday: Snow amounts up to 10-15 cm. Ridgetop winds moderate from the West. Treeline temperatures -8. Freezing levels valley bottom. Sunday: Significant change in weather. Precipitation heavy through the day, winds moderate from the SW. Freezing levels 300 m then dropping.
Avalanche Summary
Natural avalanches up to size 2.5 occurred Wednesday afternoon from mid-low elevation terrain. Sluffing is occurring from steep terrain. On Tuesday extensive avalanche control work with the use of explosives was completed. Results included 1 size 3, @ 1320 m , on an East aspect, and numerous size 1-2 on East aspects between 12-1300 m. The snowpack is very tricky at the moment. Backcountry travel requires local knowledge, extensive experience and training. The obvious clues that show snowpack instability may not be there. You need to dig deep, do your detective work and make good decisions
Snowpack Summary
Due to changing winds, wind slabs can be found on N-NE aspects and S-SW aspects in the alpine on exposed slopes at treeline. Currently, up to 60cm of snow sits over the mid February interface. This interface is variable, it consists of a strong melt freeze crust below 1000m, above 1000 m exists facets, surface hoar (in more sheltered areas), sun crust or wind press. The surface hoar is not widespread but is responsible for much of the larger avalanches that occurred earlier this week. This layer should be on your radar, as it's susceptible to rider triggers. With forecast wind, snow and rising freezing levels this layer may show its wrath again. It's a good time to play conservatively. Below this, the mid and lower snowpack is well settled and strong.
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.