Rising temperatures coupled with spring sun can pack a punch and quickly initiate natural avalanche activity and weaken cornices. Be ready to back off slopes as the surface becomes moist.
Pockets of wind slab may linger on northeasterly facing alpine slopes
30-50 cm of snow has recently fallen at upper elevations. Strong and changing ridgetop winds from the southwest to the northwest may have formed wind slabs on many aspects and could be reactive to human triggering on alpine slopes.
Cornices are large and looming along many ridgelines, and have likely grown with the recent snow and wind. They become increasingly weak when the sun comes out and freezing levels rise. They require a large berth when travelling above and below them.
The spring sun and rising freezing levels can pack a punch quickly and initiate loose wet avalanches on all aspects.
Watch for signs of instability like natural avalanche activity, wet or moist snow surfaces, and snowballing, especially on solar aspects.
Wednesday Night: Cloud with alpine temperatures near +2. Ridgetop wind light from the South and freezing levels 1400 m.
Thursday: A mix of sun and cloud with alpine temperatures near +2. Ridgetop wind light from the South and freezing levels 1300 m.
Friday: Cloudy. Ridgetop wind light from the southwest. Alpine temperatures -1 and freezing levels 800 m.
Saturday: Precipitation amounts 10-20 mm with moderate ridgetop wind from the South. Freezing level 1200 m.
No new avalanches were reported by Wednesday afternoon.
Pockets of reactive wind slab may linger on leeward slopes in the alpine. Melt-freeze snow conditions exist on most other aspects and elevations. Daytime warming may break down the crust and destabilize the upper snowpack. Back off slopes when surfaces become moist and punchy. Cornices are weak and unpredictable.
This MIN Report shows an extensive avalanche cycle in the alpine from last weekend.
Warm temperatures to the mountain top combined with the strong spring sun on Wednesday made most snow surfaces moist, except on the true North facing alpine slopes. With some overnight cooling, a melt-freeze crust may form on most aspects and elevations. Isolated pockets of wind slab may linger in the alpine just below ridgelines.
The average snowpack depth at treeline elevations is 350 cm. The snowpack below treeline is significantly shallower and isothermal.
Along ridgelines, cornices are large and looming. They are very unpredictable and require a large berth if you're travelling above and below.
