We should see sunny breaks over the next few days. Brief periods of solar radiation could be enough to trigger stubborn persistent slabs or cause cornice failures. Conservative route selection is crucial at this time.
Summary
Confidence
Fair
Weather Forecast
Thursday: Cloudy with flurries and sunny breaks – up to 5 cm. The freezing level is around 600-800 m and ridge winds are light gusting moderate from the NW. Friday: A mix of sun and cloud. The freezing level is around 600 m and ridge winds are light from the NW. Saturday: Mainly cloudy with sunny breaks and a chance of flurries. The freezing level is near valley bottom. Ridge winds are light.
Avalanche Summary
We continue to see large natural avalanches stepping down to the deeply buried persistent weak layers. On Tuesday there was one report of a size 2.5 remotely triggered avalanche where a group of skiers felt a massive whumpf at the top of a slope and realized that they triggered an avalanche on an adjacent slope almost 500 m away. On Monday there were also a couple reports of large slab avalanches. Some of these were on southerly aspects and likely involved buried sun crusts (early March interface) with avalanches up to Size 3. One was accidentally skier triggered from a Northeast aspect at treeline and likely released on the mid February weak layer. A group of snowmobilers triggered a large avalanche not far from Blue River on March 14 resulting in one fatality. Some information is available
here.
Snowpack Summary
Around 30-40 cm of recent storm snow has fallen in the past few days. There may be a variety of layers within the storm snow from thin sun crusts, to graupel balls, and maybe even recently buried surface hoar from brief clearings overnight. Also, expect fresh wind slabs in exposed lee and cross-loaded terrain. This new snow now sits on a surface hoar and/or sun crust layer. Some recent snowpack tests give moderate "pops or drops" shears on the interface between the recent storm snow and previous surface. A couple other notable persistent weaknesses remain a concern in the mid-snowpack. Another surface hoar/sun crust combo buried in early March is now down around 60-80 cm. The February 10th surface hoar/facet/crust combo is 90cm - 150cm below the snow surface and widespread throughout the region. Surface avalanches in motion and cornice fall have the potential to initiate an avalanche on this deeply buried weak layer. The mid and lower snowpack remains weak and facetted in areas with a relatively shallow snowpack.
Peter,
Avalanche Canada
