Avalanche Forecast

A ridge of high pressure continues to bring sunny and dry weather with freezing levels around 3000 m even at night. On Saturday night the ridge is forecast to break down bringing light precipitation and lowering freezing levels.

Friday night: Clear, light northwest wind, alpine low +2 C, freezing level 2900 m.

Saturday: Sunny, light northwest wind, alpine high +6 C, freezing level 3000 m.

Sunday: Mix of sun and cloud with isolated flurries, trace of new snow and rain below treeline, moderate to strong northeast wind, alpine high +2 C, freezing level lowering to 1700 m.

Monday: Sunny, light northeast wind, alpine high +4 C, freezing level 2100 m.

A widespread wet loose avalanche cycle to size 3 and several cornice failures entraining snow on the slopes below were reported on Friday and suspected to have happened over the last few days (see this MIN).  

Several small wet loose avalanches to size 1.5 on solar aspects in the alpine were reported on Tuesday.

Several cornices failed recently. Most did not trigger slabs on slopes below except for a few that triggered size 2 slabs on extreme north facing alpine slopes. 

The snow surface consists of a melt-freeze crust on solar aspects and shaded aspects up to treeline which transitions into moist/wet snow during the day. Dry snow might still be found on northerly aspects high in the alpine. 20-40 cm of recent snow has formed isolated pockets of wind slab on leeward slopes and behind terrain features. The recent snow sits on a series of melt-freeze crusts on all aspects below 1900 m and southerly aspects to mountain top. On North aspects in the alpine, the recent snow sits on dry wintery snow surfaces and possibly surface hoar on wind-sheltered slopes. 

Cornices are large, fragile and failing with warm temperatures. Many natural cornice falls were observed recently. Some triggered slabs on the slopes below.

Previous periods of warm weather are expected to have helped old persistent weak layers heal, including a few crusts buried over the last month as well as a facet layer 150 cm deep from the mid-February cold snap. However, with each day of warm weather the likelihood of triggering buried weak layers increases. 

• Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
• Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
• Avoid sun exposed slopes, especially if snow surface is moist or wet.
• The likelihood of deep persistent slab avalanches will increase with each day of warm weather.