Snowfall amounts are variable and uncertain for Sunday night. Watch for storm slabs at higher elevations.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Monday
Weather Forecast
SUNDAY NIGHT: Unstable weather will bring spotty precipitation with 5-15 cm of snow possible, gusty winds, and freezing level dropping to the valley. MONDAY: Cloudy with some lingering flurries in the morning then clearing in the afternoon, light north winds, freezing level climbing to 1600 m.TUESDAY: Sunny, moderate southwest wind, freezing level up to 1800 m after an overnight freeze.WEDNESDAY: Sunny with patchy clouds, moderate west winds, freezing level climbing to 2500 m with little overnight freeze.
Avalanche Summary
No new avalanches have been reported since Friday. On Friday, numerous storm slab avalanches up to size 2.5 were reported from explosive control, as well as loose wet avalanches released by ski cuts up to size 1.5. One natural cornice fall on Thursday was size 3, and pulled a storm slab from the slope below. On Monday, fresh storm slabs at higher elevations are the primary concern. Cornices will become a bigger concern throughout the week as temperatures warm up.
Snowpack Summary
Expect a wide range of new snow amounts on Monday morning. A total of 5-25 cm of snow could sit above a mixture of crusts and moist snow surfaces that formed during the recent warm and sunny weather. The thick supportive crust was reported to break down below 1600 m with daytime warming on Sunday. The earlier March crust is now down 40-100 cm. The December facets and November rain crust are buried deep, but they did not become reactive during the latest period of warm weather, rain, and strong solar radiation.
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.
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.