Avalanche Forecast
Issued: Feb 1st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
astclair,
Avalanche Canada
While refrozen surfaces at lower elevations pose little avalanche hazard, large avalanches may be triggered in areas with wind-drifted snow at higher elevations. Be prepared to assess conditions and adjust your travel as you gain elevation.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
Saturday night: Decreasing cloud, scattered flurries with 2-5 cm of snow, moderate west winds, alpine temperature -10 C.
Sunday: Mostly clear, light southwest winds, alpine high temperatures around -5 C.
Monday: Cloudy with periods of sun, light northwest winds, alpine high temperature -7 C.Â
Tuesday: Increasing cloud, light southwest winds, alpine high temperature -8 C.
Avalanche Summary
During the storm, numerous large, natural (size 2-2.5) storm and wind slab avalanches were reported in the region. These avalanches occurred primarily on leeward aspects (northwest, northeast, east) and mainly at treeline and alpine elevations. Reports also indicate that cornices may be reaching their breaking point and may act as triggers for these avalanches. Below tree line, small wet loose avalanches were releasing naturally on Saturday.
Over the last week, there have been two notable natural avalanches reported in the south of the region. These were large (size 2.5) avalanches breaking 200 cm deep on both northeast and northwest slopes above 2300 m. Although unlikely, these avalanches are a reminder that a deeper instability may linger in isolated areas where the snowpack transitions from thick to thin. Easier-to-trigger storm slab avalanches or cornice fall may have the potential to step-down to this layer.Â
Snowpack Summary
Snow accumulation varied widely across the region, with higher amounts falling in the eastern half. Anywhere from 20-60+ cm of storm snow has accumulated at upper elevations (generally above 1900 m). Strong southwest winds have drifted the snow into deeper, stiffer slabs in wind-exposed areas and have rapidly loaded cornices. During a warming event Saturday night, rain saturated snow surfaces up to around 1900 m that have since refrozen with cooling temperatures.
The mid and lower snowpack is generally well settled and strong. Although isolated, there are two deeper layers that may still persist. A layer surface hoar currently buried 90 to 170 cm deep from late December and a facet/crust layer from November near the ground.Â
Terrain and Travel
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Remember that the snowpack will be significantly different at higher elevations than lower down.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Problems
Wind Slabs
Strong winds from the southwest have drifted the storm snow into stiff slabs in wind-exposed areas that may be prone to human-triggering. This wind slab problem overlaps with areas where cornices have been rapidly loaded and could also act as triggers.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 2nd, 2020 5:00PM
