Avalanche Forecast
Issued: Dec 27th, 2013 7:25AM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Saturday: Cloudy with flurries or periods of snow developing later in the day 5-15 cm. The freezing level is near 500 m and winds are light from the NW switching to moderate W-SW. Sunday: Periods of snow, easing in the afternoon 10-20 cm. The freezing level should climb to around 1500 m and winds are moderate to strong from the W-SW. Monday: Periods of snow. The freezing level lowers to around 1000 m.
Avalanche Summary
Observations during the storm yesterday are very limited; however, there was one report of loud rumbling in the Shames backcountry. I would expect a fairly widespread and large natural avalanche cycle occurred. Natural avalanche activity should taper off heading into the weekend, but rider triggering remains a concern. Lower elevation explosive control on Thursday also produced wet avalanches up to Size 2.5.
Snowpack Summary
Southern Sections: The Boxing Day blitz dumped another 50-80 cm of heavy snow, accompanied by strong southwest winds. Freezing levels peaked near 2000 m right along the coast and around 1400 m further inland towards Terrace. Recently buried weaknesses of surface hoar and/or facets are now well over 1 m deep and were likely flushed out or squashed by the heavy snowfall. Forecast cooling should help stabilize the snowpack and result in a surface crust forming below treeline. Northern Sections: Storm snow totals are closer to 30-40 cm. Fresh dense wind slabs are likely in exposed lee terrain and cross-loaded features. A recently buried surface hoar layer is now down around 50-60 cm and is likely primed for rider triggering. A facet/crust layer exists near the base of the snowpack, primarily on higher NW through E facing slopes. Triggering this layer may be unlikely, but if triggered the resulting avalanche would be very large and dangerous.
Problems
Storm Slabs
It will be possible to trigger deep storm and wind slabs in steeper terrain, especially on exposed N-E aspects and at higher elevations where a surface rain crust does not form.
Use ridges or ribs to avoid pockets of wind loaded snow.>Choose well supported terrain without convexities.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Mainly an issue in the northern part of the region where the snowpack is less deep and a weakness of facets and/or a crust is found near the base of the snowpack.
Avoid shallow snowpack areas where triggering is more likely.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 28th, 2013 2:00PM