Warm air temperatures with strong afternoon sun may destabilize the upper snowpack on south-facing slopes. Use extra caution on sun exposed slopes during the afternoon.
Confidence
Fair - Timing or intensity of solar radiation is uncertain
Weather Forecast
Warm and sunny is the theme for the next 3 days. On Sunday, mainly sunny conditions are expected with freezing levels reaching around 2000m. Alpine winds are expected to be moderate from the NW. On Monday, mainly sunny conditions are expected with freezing levels reaching upwards of 2500m. Alpine winds are again expected to be moderate from the NW. Conditions are currently forecast to be the same on Tuesday morning with increasing cloudiness during the afternoon.
Avalanche Summary
On Saturday, wet sluffing was reported from steep sun exposed slopes in the Lizard range. Similar conditions are expected on Sunday. Human-triggering of old wind slabs also remains possible in isolated areas.
Snowpack Summary
In sheltered areas, up to 10 cm of snow from earlier in the week sits over a previously variable snow surface which was a mix of surface hoar, crusts, wind affected surfaces, and/or dry powder. Ongoing winds have redistributed the new snow in wind-exposed terrain resulting in a highly variable snow surface and the formation of thin wind slabs in leeward features. The most prominent snowpack feature is a thick supportive crust around 10-30 cm below the surface. It extends up to around 2200m elevation. Below this elevation the crust is effectively capping the snowpack, preventing riders from stressing deeper persistent weak layers. In alpine areas where the crust is not present or is less thick, it could still be possible to trigger a deep avalanche from rocky sun-exposed slopes, thin snowpack areas, or with a heavy load (i.e. cornice fall).
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.