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 South Coast will 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 (up to 20mm) precipitation, with freezing levels rising to 1300m. Ridgetop winds will be moderate from the SE, 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 today.
Snowpack Summary
Surface snow conditions consist mainly of crusts that have developed due to melt/freeze conditions, and direct solar impact on steep Southerly aspects. Northerly aspects still host dry, wintery snow. On lee slopes in the alpine there are pencil-4 finger hard wind slabs. Surface faceting is occurring on sheltered, shady aspects. While shallow, rocky slopes are faceting and weaker; posing a threat to deeper releases. Surface hoar development up to 5mm has been reported at treeline, and below treeline. These may be our next layers of concern once buried. The Feb 01 (120201) rain crust is down 10-40 cm up to about 2000 meters. The mid-January crust is down between 50-100 cm, and the mid December crust is buried down up to 200 cm. The average snowpack depth at 1650m is near 240cm.
Problems
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.
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.