Another system bringing snow beginning Tuesday night. Totals amounts of 30-40cm by Thursday with moderate westerly winds will result in additional load on the Feb 10 layer and will be capable of producing some larger avalanches.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain on Wednesday
Weather Forecast
Current forecasts are showing snow beginning tonight with 30-40cm possible by late on Thursday. Winds will increase to moderate out of the west. Freezing levels will drop to approx 1500 meters.
Avalanche Summary
Isolated sluffing from steep alpine terrain. Two Size 2.5 and one Size 3 natural have occurred in the past 24 hours One of the Size 2.5 on Mt Murray was triggered by a cornice failure and caused a sympathetic release on an adjacent slope which ran full path to near the bottom of the runout. The failure plane was the Feb 10 interface. The second Size 2.5 initiated in a steep shallow rocky area and ran on ground.
Snowpack Summary
Surface hoar growth noted in sheltered areas below treeline with some surface facetting also observed. Solar aspects have a thin crust from Monday that is becoming moist by midday. The previous storm snow has settled into a soft slab 20-40cm thick in the alpine and open areas at treeline in immediate lee features - so far they appear to be well bonded to previous surfaces. The Feb 10 layer is down anywhere from 80-120cm and is still producing sporadic natural and human triggered avalanche activity.
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.