Sea to Sky Avalanche Forecast
Jan 10th, 2020 4:00PM
The storm snow was distributed by strong southerly wind on Friday. New snow overnight will hide recently formed wind slabs and make terrain selection trickier. Carefully evaluate the snowpack as you transition into avalanche terrain and travel conservatively.
FRIDAY NIGHT: Cloudy with snowfall, up to 15 cm snow accumulation, light westerly wind, alpine temperature -5 C, freezing level at 1000 m.
SATURDAY: Mostly cloudy, light to moderate northwest wind, alpine temperature -9 C, freezing level dropping to valley bottom.
SUNDAY: Cloudy with snowfall, accumulation up to 15 cm, light southwest wind, alpine temperature -10 C, freezing level at valley bottom.
MONDAY: Mostly cloudy, light westerly wind, alpine temperature -20 C, freezing level below valley bottom.
On Friday, a large (size 2) machine triggered avalanche was reported. It released on a deeper weak layer in the snowpack. Several small (size 1) avalanches released naturally or were triggered by skiers within the new storm snow.
On Thursday, several explosive triggered and a few natural avalanches up to size 3 were reported.
On Wednesday, numerous avalanches up to size 3 were triggered with explosives. Most avalanches were storm slabs and released in the recent storm snow. However, some avalanches released on a deep weak layer from mid November and were 1.5 m deep. A few storm slab avalanches up to size 2.5 ran naturally.
The storm on Friday brought up to 30 cm of snow with strong southerly wind. The snow fell on a very variable snowpack with a wind affected snow surface in the alpine and at treeline elevations and deep soft snow in non wind affected locations. The old snowpack has not quite recovered and gained strength from the snow storms of the last week which delivered 150 cm with varying temperatures and strong south to southwest wind. Those previous storms have loaded a weak layer of feathery surface hoar buried around 100 to 180 cm in some areas of the region.
In parts of the region near the bottom of the snowpack around 150 to 250 cm deep, sugary faceted grains and a hard melt-freeze crust exist from mid-November. This is is an indicative snowpack setup for large and destructive avalanches. The likelihood of human-triggered avalanches decreases as the layer gets deeper but the consequence of triggering it would be severe.
Terrain and Travel
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
- Make observations and assess conditions continually as you travel.
- Caution around slopes that are exposed to cornices overhead.
Valid until: Jan 11th, 2020 5:00PM