A storm has ramped up avalanche danger in the region, particularly in areas that have seen more than 20 cm of new snow. Deeper in the snowpack, the added load will test persistent weak layers.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Winds strong from the southwest. Freezing level to 900 metres with alpine temperatures of -4. Monday: A mix of sun and cloud. Winds moderate to strong from the northwest. Freezing level returning to valley bottom with alpine temperatures around -11. Tuesday: A mix of sun and cloud. Winds light from the north. Alpine temperatures of -13.
Avalanche Summary
Stormy weather has been obscuring visibility of higher elevation avalanche terrain, but warm valley temperatures have allowed numerous loose wet avalanches to be observed occurring at lower elevations. Reports from earlier in the week included a few avalanches up to size 3.0 remotely triggered in the Kispiox area on Monday on south through west aspects at 1700-1800 metres. These avalanches were about 80 cm deep and are suspected to have released on the December 25th surface hoar. Aside from new storm slabs being formed and becoming a problem in their own right, it should be noted that these slabs are introducing a new load above our deeper snowpack weaknesses, increasing their likelihood of triggering.
Snowpack Summary
Stormy weather over Friday and Saturday has delivered anywhere from 10-25 cm of new snow to the region. Including snow from earlier in the week, 15-50 cm of storm snow now sits above a widespread rain crust up to about 1300 m. At treeline and above, the storm snow overlies wind slabs recently formed on lee and cross loaded features. Ongoing snowfall has effectively shifted this wind slab problem into a more generalized storm slab issue. Below our the storm snow forming the upper snowpack, several buried surface hoar layers can be expected roughly 35-75 cm deep. These layers have recently yielded moderate to hard results in snowpack tests. Many areas have hard slabs in the upper snowpack above weak sugary snow near the ground. Triggering a deep persistent slab above this sugary snow will remain a low probability high consequence scenario for some time, with probability increasing as new snow and strong winds add load to the snowpack. Snow profile information from Tuesday at Hankin reported 110cm at treeline with a buried surface hoar layer down 25 cm and weak facetted snow down 75 cm as well as depth hoar above the ground. You can see the full report on the MIN.
cgarritty,
Avalanche Canada
