Avalanche Canada ghelgeson, Avalanche Canada

Sea to Sky Avalanche Forecast

Jan 13th, 2020 4:00PM

Reverse loading has likely formed wind fueled storm slabs in strange places at and above treeline, but cold temperatures should allow them to settle out rather quickly. The ticket Tuesday is seek out wind sheltered terrain where the riding should be great. 

Summary

Confidence

Low - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

After a stormy period it looks like the intensity of the weather will briefly back off until Tuesday night before a series of storms line up for the rest of the week and into the weekend.

MONDAY NIGHT: Freezing level at valley bottom, light northwest wind at most elevations, moderate west wind at ridgetop, no significant precipitation expected.

TUESDAY: Broken cloud cover, freezing level at valley bottom, light southwest wind at most elevations, moderate west wind at ridgetop, trace of snow possible during the day, 5 to 10 cm possible Tuesday night.

WEDNESDAY: Broken cloud cover, freezing level at valley bottom, light to moderate wind generally out of the south, 2 to 6 cm of snow possible during the day, 5 to 20 cm of snow possible Wednesday night.

THURSDAY: Broken cloud cover, freezing level at valley bottom, light to moderate wind generally out of the south, 2 to 6 cm of snow possible.

Avalanche Summary

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. On Sunday funky wind out of the N/NE associated with an Arctic Front likely formed fresh wind slabs in locations we aren't used to seeing them. The subsequent cold temperatures should be helping the upper snowpack to settle out quite rapidly.

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 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

  • Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
  • Be aware of highly variable recent wind loading patterns.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.

Valid until: Jan 14th, 2020 5:00PM