Sea to Sky Avalanche Forecast
Jan 9th, 2020 4:00PM
The avalanche danger increases during the day with continuing snowfall and moderate to strong southwest wind. The danger is closely related to increasing snowfall amounts.
THURSDAY NIGHT: Cloudy with increasing snowfall, up to 15 cm of snow, light to moderate southwest wind, alpine temperature -10 C, freezing level at valley bottom.
FRIDAY: Cloudy with snowfall, accumulation 20 to 40 cm, moderate to strong southwest wind, alpine temperature -9 C, freezing level rising from valley bottom to 600 m.
SATURDAY: Cloudy with flurries, up to 30 cm snow accumulation overnight, light to moderate westerly wind, alpine temperature -6 C, freezing level at 500 m.
SUNDAY: Cloudy with snowfall, accumulation 10 to 30 cm, light to moderate southerly wind, alpine temperature -8 C, freezing level at 400 m.
On Thursday, several explosive triggered avalanches of size 2 and 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.
On Tuesday several storm slabs up to size 2 and one size 2.5 were triggered with explosives, by skiers and a machine.
A natural avalanche cycle occurred on Monday during the peak of the storm. Numerous avalanches ran on deeper weak layers and avalanche sizes ranged from 1 to 3.5. Storm slabs were reactive to explosives with large (size 2) avalanches being released.
The new snow which will fall overnight (up to 15 cm) and during the day on Friday (20 to 40 cm) will cover 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. This next storm is accompanied with cold temperatures and it is uncertain how fast the new snow will bond with the old snow surface. 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. The previous storms might have loaded a weak layer of feathery surface hoar buried around 100 to 180 cm.
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
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Avalanche hazard is expected to to increase througout the day, think carefully about your egress.
- Make observations and assess conditions continually as you travel.
- If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
Valid until: Jan 10th, 2020 5:00PM