New snow followed by heavy rain is Tuesday's recipe for rapidly changing and dangerous avalanche conditions.
Forecast weather suggests a substantial storm slab problem could form with new snow before precipitation switches to rain on Tuesday. Fresh accumulations will shed from steep slopes increasingly easily as temperatures rise.
New snow followed by a deluge of rain will breathe new life into wet loose avalanche problems on Tuesday. The more new snow has accumulated before the transition to rain occurs, the greater the danger will be.
Monday night: Cloudy with increasing wet flurries bringing 5-10 cm of new snow. Moderate southwest winds.
Tuesday: Wet flurries transitioning to heavy rain in the afternoon; 30-50 mm accumulation. Strong south or southwest winds, increasing over the day and overnight. Treeline temperatures rising from around 0 to +4 over the day as freezing levels climb from 1400 to 2900 metres.
Wednesday: Heavy rain; 40 mm accumulation. Strong south or southwest winds. Treeline high temperatures around +4.
Thursday: Mainly clear. Light to moderate northwest winds. Treeline high temperatures around -4.
Tuesday's forecast suggests we will see a rapid evolution of avalanche conditions over the day. Depending on freezing levels and snowline elevations, we could see substantial storm slabs form in the region's upper elevations before they are hammered by rain in the afternoon. A rapid transition from widespread touchy storm slabs to equally touchy wet loose avalanche conditions is expected to occur over the day.
Heavy rain has affected the snowpack at all elevations. The current forecast suggests we may see 15-25 cm of new snow accumulate before Tuesday afternoon when heavy rain takes over and once again drenches the snowpack at all elevations.
Average treeline snow depths are around 80-100 cm with much of treeline and all but the uppermost below treeline elevations still below threshold depths for avalanches.
