Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A substantial storm system is expected to reach the south coast on Saturday morning. There is some uncertainty regarding how much of the heavy coastal precipitation will reach the inland regions. Precipitation and strong winds are expected for Saturday and Sunday but conditions should progressively ease during the day on Sunday. A ridge of high pressure should begin to build on Monday.Saturday: Precipitation 5-15mm, freezing levels am: 1000m pm: 1800m, ridgetop wind 40-60 km/h SW in the afternoonSat. Night/Sunday: Precipitation 15-30mm, freezing levels am: 1800m pm: 1500m, ridgetop wind 40-60 km/h SW in the morning, easing during the dayMonday: Light flurries, freezing levels am: 800m pm: 1000m, ridgetop wind light NW
Avalanche Summary
No new slab avalanches reported. Isolated loose snow activity from steep solar features during the heat of the day.
Snowpack Summary
The new snow is sitting on a weak layer consisting of a well-developed sun crust on solar aspects, surface hoar in sheltered areas, and a widespread temperature/rain crust at lower elevations. Strong forecast storm winds will quickly form new wind slabs on leeward slopes.The warm weather has resulted in good settlement of the snowpack and most of the layers are well bonded. There are still two weak layers that remain a concern but the problem is becoming isolated. However, the weight of the new storm snow may reactive these layers. The early March layer is down 60-100cm and the early Feb layer is down roughly 1.5m. It seems like these persistent weak layers are more of a concern in the northern parts of the region but may still pose a threat in the Coq and south.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.