A storm is ramping up avalanche danger in the region. New snow and wind will build storm slabs on Saturday. Deeper in the snowpack, the added load will test persistent weak layers.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
Friday night: Flurries bringing 5-10 cm of new snow. Winds strong to extreme from the south. Saturday: Flurries bringing another 5-15 cm of new snow. Winds strong to extreme from the southwest. Freezing level to 1200 metres with alpine temperatures of -2. Sunday: Mainly cloudy with scattered flurries and up to 5cm of new snow. Winds moderate to strong from the southwest. Freezing level to 900 metres with alpine temperatures of -3 Monday: A mix of sun and cloud with no new snow. Winds moderate to strong from the northwest. Freezing level back to valley bottom with alpine temperatures around -12.
Avalanche Summary
No new avalanches have been reported, but a few large avalanches up to size 3.0 were 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. New storm slabs are expected to continue developing through Saturday. Aside from being a problem in their own right, these slabs will introduce a new load above our deeper snowpack weaknesses and increase their likelihood of triggering.
Snowpack Summary
After a trace to 10 cm of new snow Thursday night, 5-30 cm of settled storm snow now sits above a widespread rain crust up to about 1300 m. At treeline and above, the new snow will overlie wind slabs recently formed on lee and cross loaded features. Ongoing snowfall and strong winds will continue to shift this wind slab problem into more of a general storm slab over the coming days. Below our new snow, several buried surface hoar layers have been reported 25-50 cm deep and continue to yield 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 our forecast snowfall adds load to the snowpack. Snow profile information from Tuesday at Hankin reports 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
