The hot and sunny weather persists on Friday. The danger will be the highest when the day heats up. Set up your plan to avoid sun-exposed slopes and overhead exposure during the heat of the day.
Weather Forecast
THURSDAY NIGHT: Clear skies, light southeast wind, alpine temperature 5 C, freezing level 3000 m.FRIDAY: Partly cloudy skies, light southeast wind, alpine temperature 4 C, freezing level 2800 m.SATURDAY: Cloudy with light snow in the alpine and rain below, accumulation 2 to 5 cm, light west wind, alpine temperature 0 C, freezing level 2000 m.SUNDAY: Cloudy with snowfall, accumulation 1 to 3 cm, light southeast wind, alpine temperature -3 C, freezing level 1600 m.
Avalanche Summary
Many wet loose avalanches were observed between Sunday and Wednesday. They were large (up to size 3), occurred mostly on southeast to southwest aspects, and at all elevations. A couple persistent slab avalanches were also triggered by skiers, 40 to 80 cm deep and on south and north aspects in alpine terrain. This avalanche cycle may continue on Friday on sun-exposed slopes, as temperatures remain exceptionally warm and the sun shines strong. The cycle should end on Saturday, as freezing levels drop and cloudy skies prevail.
Snowpack Summary
The warm air and sunny skies have produced wet snow to ridge top on southerly aspects and up to around 1800 m on northerly aspects. The upper 40 to 60 cm of snow may slide easily during the day on sun-exposed slopes, either as loose wet snow or as a cohesive slab, as this snow sits over weak faceted grains or a melt-freeze crust. The wet snow may freeze into a melt-freeze crust overnight.Below treeline, a weak layer of faceted grains and/or feathery surface hoar crystals may be found around 70 to 120 cm deep. Although this layer has been dormant for a few weeks, the current warm conditions may awaken this layer. Steep cutblocks and large open glades at lower elevations are the most likely places to trigger this layer.The lower snowpack is generally consolidated and strong. The exception is around thin, rocky areas in the alpine, where the snowpack is composed of faceted snow. The warm air and sunny skies could trigger very large avalanches that could run to the valley bottom.
Problems
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.