Avalanche Forecast

Moderate - Timing or intensity of solar radiation is uncertain

A mix of sun and cloud is expected for Sunday with light intermittent flurries possible. Freezing levels are expected to fall to valley bottom overnight and climb to around 1000m on Sunday afternoon. Alpine winds are forecast to be light from the northwest. Light snowfall is forecast for Monday but less than 5cm is expected. Freezing levels are expected to reach around 1000m on Monday and alpine winds are forecast to be moderate from the northwest. Similar conditions are expected for Tuesday with light snowfall, cool temperatures, and moderate west winds.

Widespread natural avalanche activity up to size 3 was reported to have occurred during the storm Thursday overnight and Friday morning. Most of this natural activity was on wind loaded aspects (north through east) in the alpine and at treeline but a few avalanches were also reported on south and west aspects. Explosive use on Friday produced mainly size 2-3 storm slabs 20-50cm thick on a variety of aspects above 2300m. Some of the explosive results are assumed to be failing on persistent weak layers with slab depths up to 100cm. Also reported were a couple size 1-1.5 human-triggered storm slab avalanches. These were 25-30cm thick slabs. On Thursday, several natural and human triggered 50-60cm thick persistent slab avalanches up to Size 2 were reported running on surface hoar buried at the beginning of January. Some were remotely triggered by as much as 30m away. Natural activity is generally not expected on Sunday but could be possible on steep south facing slopes if the sun comes out in full strength in the afternoon. Recently formed wind slabs and a reactive persistent slab are both expected to be sensitive to human-triggering on Sunday.

Weakness linger within and under the 20-30cm of rapidly settling recent storm snow with reports of moderate sudden results in snowpack tests. Southwesterly winds have continued to build fresh wind slabs on the leeward side of ridge crests and behind terrain features on cross-loaded slopes. The persistent weak layer of surface hoar buried early-January is now typically down 50-80 cm and appears to be quite touchy in some parts of the region. In general, the lower snowpack below this layer is well settled and strong.