Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Friday
Weather Forecast
The weather patterns will start to change on Wednesday. The inland regions may see light amounts of precipitation starting in the afternoon with freezing levels near 1000m. They could rise to 1500m later in the afternoon. Thursday into Friday may bring light-moderate precipitation, with freezing levels rising to 1600m. Ridgetop winds will be moderate from the SW, switching Southerly towards the end of the forecast period. Weather models disagree; confidence in precipitation amounts is poor.
Avalanche Summary
No new avalanche observations reported.
Snowpack Summary
Snow surface conditions are variable. Thin, breakable sun crusts have developed on steep solar aspects in the alpine. Melt freeze crusts exist at lower elevations on most aspects. At treeline and below treeline surface faceting and surface hoar growth (5mm) are forming; especially on shady aspects in sheltered locations. In the Duffy Lake and Coquihalla sits a well settled snowpack below the variable surface conditions. Additionally in the Coquilhalla hard wind slabs 5-15cm thick and have formed due to strong outflow winds. Cornice fall is still a concern under the sunny skies and could trigger a large slab avalanche from the slope below. The older storm slab in the Coquihalla is about a meter deep and continues to settle and bond.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.