We're moving into a period of HIGH danger with rapid loading of the snowpack on Wednesday and Thursday: rain to treeline and heavy snow in the alpine.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Warm and wet on Wednesday - Thursday. Cooling with light preciptation on Friday. WEDNESDAY: Rain to treeline (30-40mm) ; wet heavy snow in the alpine (30-40cm) / Strong southerly winds becoming moderate / Freezing level around 1900m / High temperatures to +2 Celsius. THURSDAY: Wet snow (20-40cm) / Moderate southeasterly winds / Freezing level around 1800 m. FRIDAY: Mostly cloudy with isolated flurries / High temperatures to +1 Celsius / Light-moderate southerly winds / Freezing level around 900 m.
Avalanche Summary
Several loose wet avalanches to Size 3 were seen on steep solar aspects on Monday.
Snowpack Summary
The recent warming and sunny conditions gave us a widespread sun crust on all but high northerly (and some westerly) aspects, where there is still some cold snow to be found. 40-80 cm of storm snow fell last week with moderate to strong southerly winds - this formed variable wind slabs on northerly aspects. Changing temperatures during the storm made the slab problem worse and created layers that are still giving sudden results down 30, 40, and 60cms in snowpack tests. The new snow has buried a wide variety of old snow surfaces including stiff wind slab or wind affected snow at upper elevations, sun crust on steep southerly slopes, surface hoar (up to 10 mm) in sheltered locations.In sheltered ares where the recent storm snow is overlying surface hoar (weak, feathery crystals), you may see increased reactivity on this layer as the storm snow begins to settle into a more cohesive slab. The mid and lower snowpack is generally well settled (strong). However, there remain a number of facet and crust layers (down 60-80cm in shallower areas) that are currently dormant but will require monitoring with additional loading (and warming this week), especially in the shallow, rocky areas.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.