Avalanche Forecast
Issued: Jan 14th, 2017 5:02PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
cgarritty,
Avalanche Canada
Maintain caution around wind slabs at higher elevations. Slabs in steep terrain and on unsupported slopes will likely remain reactive to human triggering.
Summary
Confidence
Moderate -
Weather Forecast
Sunday: Cloudy with sunny periods and no new snow. Winds light from the southwest. Freezing level rising to 900 metres with alpine temperatures to -5.Monday: Periods of snow with approximately 20 cm accumulations. Winds light tot moderate from the southwest. Freezing level to 1000 metres with alpine temperatures around -4.Tuesday: Heavy snowfall with 25-35 cm accumulations. Winds moderate to strong from the southwest. Freezing levels rising to 1700 metres with alpine temperatures exceeding 0.
Avalanche Summary
Reports from Friday include several size 1-1.5 wind slab avalanches releasing from steeper terrain on mostly north to northeast aspects. A report of particular interest details a Size 2 avalanche releasing from a lower-angle south aspect in the Valhalla Range. Although isolated, it being reported to have failed on the 25 cm-deep December 26 surface hoar layer raises concern for shallower snowpack areas. On Thursday, several human-triggered wind slabs in the size 1-1.5 range were triggered on a wide range of aspects at treeline. Wind slabs will likely remain reactive over the short term.
Snowpack Summary
Recent cold and clear weather has promoted both faceting of surface snow as well as the growth of surface hoar that has been reported to be up to 10mm in size in some areas. Reports also exist of a sun crust beginning to form on steep solar aspects. Below the surface, up to 30 cm of low density snow fell earlier this week. During and in the days after the storm, moderate to strong southwest and then northerly winds shifted this snow into reactive wind slabs on leeward slopes. The mid-December facet/surface hoar persistent weakness can be found buried 70-120 cm deep and is generally considered dormant. However, we are still receiving occasional reports of sudden results in snowpack tests, suggesting that it has to potential to propagate into a large avalanche if triggered, particularly in shallow spots where this layer is closer to the snow surface. The lower snowpack is well bonded and features a thick rain crust near the ground.
Problems
Wind Slabs
Shifting winds recently formed wind slabs on many aspects in exposed alpine and treeline areas. Tune in to patterns of recent wind loading as you travel and be especially cautious of thin trigger points.
Watch for signs of instability such as whumpfing, or cracking. Avoid areas where the snow feels stiff or slabby.Be cautious as you transition into wind affected terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 15th, 2017 2:00PM
