Sea to Sky Avalanche Forecast
Jan 11th, 2020 4:00PM
Up to 30 cm of snow can fall in some parts of the region by the end of the day on Sunday. The new snow will form slabs in lee terrain features in the alpine and around treeline with moderate southwest wind.
SATURDAY NIGHT: Cloudy with snowfall, accumulation 10 to 15 cm, light to moderate southwest wind, alpine temperature -10 C, freezing level at valley bottom.
SUNDAY: Cloudy with snowfall, accumulation 10 cm to 20 cm, light southwest wind, alpine temperature -10 C, freezing level at valley bottom.
MONDAY: Mostly cloudy with isolated flurries, light southwest wind, alpine temperature -18 C, freezing level below valley bottom.
TUESDAY: Mostly cloudy with isolated flurries, light southwest wind, alpine temperature -18 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 of the past days 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.
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.
- Storm slab size and sensitivity to triggering will likely increase through the day.
Valid until: Jan 12th, 2020 5:00PM