Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
A firmly embedded ridge of high pressure in Alberta seems to be causing systems to fizzle once they reach the Columbia Mountains. On Friday light snowfall is expected but should taper-off with only trace amounts forecast for Saturday/Sunday. Winds should be light and west/northwesterly throughout the period with freezing levels peaking at about 1300m.
Avalanche Summary
Large chunks of cornice fall have been reported in recent days with limited effect on the slope below. Minor radiation sluffs on steep solar aspects. Otherwise, no new activity to report.
Snowpack Summary
Very warm alpine temperatures recently melted surface snow layers. A crust now exists to ridge top on solar aspects. Large weak cornices are plentiful and recently developed wind slabs may exist in certain areas. The upper snowpack appears to be settling well. Below about 1500m, crust/facet layers buried in early January are still causing some operators concern as well as widespread facets that were buried on January 20th. These layers represent a low probability/high consequence scenario. If you're traveling in the mountains now is a great time to take stock of current surface conditions (surface hoar, crusts) that will probably get buried at some point on Friday.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.