Forecasts are calling for up to 20cm of snow overnight with strong SW winds and warm temperatures. This will keep the hazard elevated. Storm slabs will become increasingly sensitive with the new load. Cautious route finding is recommended.
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Freezing levels are expected to rise through the early evening before cooling off Sunday morning. Another 20 to 25cm of new snow could fall by morning, with a chance of rain at lower elevations. Winds are expected to be strong from the west, and temperatures will be slightly cooler on sunday. A brief sunny break is possible Sunday morning after the snow storm.
Avalanche Summary
No new avalanches were observed today, but visibility was very limited.
Snowpack Summary
New snow amounts were variable across the forecast area with 10 to 15cm falling at treeline overnight. With the warm temperatures the snowpack is settling rapidly. In the alpine and wind prone areas at treeline soft slabs continue to form. These slabs are sensitive to human triggering where they lie on previously formed crusts. The February surface hoar is still in the back of our minds and is triggerable by heavy loads such as cornices.
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.