Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
TUESDAY: Freezing level at 1000m with an above freezing layer between 2000 & 2500m. Ridge top winds moderate west. Scattered cloud. No precip.WEDNESDAY: Freezing level should stick around 700m all day. Ridge top winds moderate SW. Light snow begins around lunchtime, I expect 5 – 10cm by sundown. THURSDAY: Freezing level should stay around 500m all day. Isolated flurries, but no significant accumulations. Ridge top winds mod – strong NW.
Avalanche Summary
Recent activity has been limited to size 1 loose snow avalanches on slopes receiving direct sun. Interestingly, a glide avalanche was observed on Mt. Fernie Saturday.
Snowpack Summary
Intense recent winds have redistributed snow and created large cornices. The snow surface is now a mix of sastrugi, hard slab and soft slab in open areas. While the effects of the wind were dramatic, the sensitivity of the wind slab to triggering is decreasing. With the warm temps, slopes receiving direct sun are moistening in the afternoon. Surface hoar is continuing to form in protected areas too. Reports indicate that the crystals are as big as 20mm. Below this around 50cm of settled snow rests on a myriad of old surfaces (January 4th interface) that include sun crust on steep south and west facing terrain, surface hoar in sheltered locations at treeline and below and facets everywhere else. Tests on this interface are still yielding sudden planar results, but the overlying slab has settled significantly and there haven't been any reported avalanches on this layer in some time now. There are some reports of glide cracks on Mt Fernie, these mysterious phenomena should be given a wide berth.
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.