Avalanche Canada ghelgeson, Avalanche Canada

Sea to Sky Avalanche Forecast

Jan 14th, 2020 3:00PM

Wednesday's storm snow will begin to hide the damage caused by strong north wind earlier this week. Seeking out sheltered trees will keep you out of wind slab territory and offer the best riding as the first in a series of storms impacts the region.

Summary

Confidence

Low - Uncertainties in both the snowpack structure and the weather forecast limit our confidence.

Weather Forecast

We’re moving into a period where it’s one storm after the next for the foreseeable future and it should warm up a bit beginning Friday night.

TUESDAY NIGHT: Light southwest wind at most elevations, strong west wind at ridgetop, 3 to 10 cm of light density snow possible.

WEDNESDAY: Overcast, freezing level at valley bottom, light to moderate wind generally out of the south, 5 to 20 cm of very light density snow possible during the day with potential for 20 to as much as 50 cm of snow Wednesday night, stay tuned for more details.

THURSDAY: Broken cloud cover, freezing level at valley bottom, moderate to strong wind generally out of the south, 8 to 20 cm of snow possible.

FRIDAY: Broken cloud cover, freezing level at valley bottom, moderate wind generally out of the south, 1 to 5 cm of snow possible.

Avalanche Summary

On Monday avalanche activity was tempered by very cold temperatures. Control work produced avalanches to size 1.5 in alpine features with crown depths up to 20 cm.

On Sunday the top 30 to 40 cm of recent snow was sensitive to control work producing avalanches up to size 2 on what seems to be all aspects.

On Saturday, several large (up to size 2.5) slab avalanches were triggered with explosives control work. A few small (size 1.5) slab avalanches were triggered by skiers.

Snowpack Summary

About a meter of storm snow has fallen in the last week which made for some phenomenal riding conditions. Over the last two days winds have been out of the south/southwest, but previous to this strong north winds created some reverse loading in wind exposed features, especially those near ridgetop. The subsequent cold temperatures should be helping the upper snowpack to settle and stabilize.

A weak layer of snow known as the late December surface hoar is now 70 to 200+ cm below the snow surface. Tests from snow profiles show this interface likely remains sensitive to human triggering, but not everywhere. Problem locations are places where the snowpack goes from thick to thin, steep unsupported slopes and around rock outcroppings.

The beginning of the season had less precipitation than usual, and there are sugary faceted grains as well as a hard melt-freeze crust near the base of the snowpack. In a more seasonally normal winter we wouldn't be thinking about this interface, but it has produced large destructive natural avalanches as recently as January 11th.

Terrain and Travel

  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Carefully evaluate steep lines for wind slabs.
  • Conditions may have improved, but be mindful that deep instabilities are still present.

Valid until: Jan 15th, 2020 5:00PM