Incoming weather combined with a complex snowpack means this is no time to be pushing into steep terrain. Conservative slope selection is critical to safe mountain travel.
Confidence
Poor - Intensity of incoming weather systems is uncertain on Sunday
Weather Forecast
Overview: A pacific frontal system will push inland on Saturday bringing moisture to the interior until early Monday morning. Expect a ridge of high pressure to develop for Monday and Tuesday. Due to significant weather model disagreement for Sunday, I have limited confidence in forecast snowfall amounts and freezing levels.Sunday: Moderate snowfall with the greatest amounts falling in the south / Moderate westerly winds with extreme gusts / Freezing level between 1700m and 2000mMonday: A mix of sun and cloud / Moderate westerly winds becoming northwesterly with strong gusts / Freezing level at 1500mTuesday: Mainly sunny skies / Light northwest winds / Freezing level at about 1200m
Avalanche Summary
A recent natural cornice triggered Size 2.5 avalanche was observed Smith Basin area north of Elkford. I expect a new round of storm slab activity with forecast weather. Rain at lower elevations may activate wet slab avalanches.
Snowpack Summary
Light to moderate amounts of new snow overlie crusts on previously sun-exposed slopes. The bond between the new snow and the freshly buried crusts is expected to be quite weak. With more snow and wind on the way, the size and reactivity of the developing storm slab will increase. Forecast rain at lower elevations may also reactivate potent wet slabs.The deep facet/crust persistent weakness buried at the beginning of February, now down up to 150cm, is still producing sudden results in snowpack tests. I would be very leery of any slopes that have not already avalanches as any avalanches at this interface would be large and destructive. Triggering will become more likely if forecast precipitation falls as rain.Cornices have also become large and potentially unstable.
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.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
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.