North Columbia Avalanche Forecast

Feb 17th, 2020 5:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Storm Slabs.

Carefully assess terrain where triggering storm slabs is possible such as slopes that are getting hit by the sun, wind-loaded, or steep and convex.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

MONDAY NIGHT: Partly cloudy, moderate northwest wind, alpine temperatures drop to -10 C.

TUESDAY: Sunny with a few clouds in the morning, light northwest wind, alpine high temperatures around -6 C.

WEDNESDAY: Sunny, light wind, alpine high temperatures around -6 C.

THURSDAY: Sunny, moderate southwest wind, alpine high temperatures around -6 C.

Avalanche Summary

Several small (size 1-1.5) skier triggered slab avalanches were reported on Sunday. These avalanches were 20-60 cm thick and released on a wide variety of elevations and aspects. The pattern of triggering wind slabs on north and east facing slopes at higher elevations continued. However, there were also a few reports of slab avalanches in sheltered terrain including some small slabs triggered above the rain crust at low elevations in steep gully features, and some small slabs failing on a sun crusts (on southeast treeline slope) and surface hoar (on a west aspect in the trees). Although these avalanches have been small, they highlight the potential to trigger slabs on a wide variety of terrain.

Snowpack Summary

30-60 cm of recent snow is beginning to settle and there is uncertainty about whether it will gain or loose strength in the coming days. There have been a few reports of this snow showing reactivity in isolated sheltered terrain features such as openings at and below treeline (where it sits above small surface hoar or sun crusts) and steep gully features where the snow may be poorly bonded to the early February rain crust. The lower snowpack is generally well settled and strong.

Terrain and Travel

  • Start on smaller terrain features and gather information before committing to bigger terrain.
  • Be carefull around freshly wind loaded features.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

Storm Slabs

An icon showing Storm Slabs

Likelihood

Possible

Expected Size

1 - 2

30-60 cm of snow from the past week is gradually settling and gaining strength, but it could still be possible to trigger storm slabs across a variety of terrain. Wind loaded terrain is the most likely place to trigger slabs, but snow at sheltered lower elevations could become unstable on isolate steep terrain features as well.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Feb 18th, 2020 5:00PM