Watch for signs of changing stability as the temperature rises during the day.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A warm, wet storm system will reach the coast early Monday. The Cariboos should remain dry for Monday and a mix of sun and cloud is expected. Temperatures will rise rapidly on Monday with the freezing level reaching 1500-2000m and winds increasing to moderate in the alpine. On Tuesday, the Cariboos will begin to see precipitation (3-6mm) and the freezing level is expected to be around 2000m. Wednesday is expected to be similar with freezing levels around 2000m and precipitation. Amounts are uncertain for Tuesday night and Wednesday with models currently showing 10-30mm. Strong alpine winds from the SW are expected for both Tuesday and Wednesday.
Avalanche Summary
The storm snow is reactive to ski cutting and is producing isolated avalanches up to size 1. I expect wind loaded areas in the alpine to be the main concern at the moment.
Snowpack Summary
Around 15cm of new snow sits on a weak layer of surface hoar. Reports from the region suggest that anywhere from 50-150 cm of settling snow overlies one or more weak layers which formed during November. Snowpack tests suggest that these weak layers are getting harder to trigger but still have the potential to produce large avalanches if triggered. Recent wind has created wind slabs in lee features in exposed alpine terrain.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.