Confidence
Fair - Intensity of incoming weather is uncertain
Weather Forecast
An approaching frontal system is expected to reach the Interior Thursday night, bringing moderate amounts of snow at upper elevations. Overnight Thursday: Snow amounts 10-20 cm. Ridgetop winds moderate from the SW. Freezing levels 1300 m. Friday: Snow amounts 2-5 cm. Ridgetop winds moderate from the SW. Freezing levels 1700 m. Saturday/Sunday: An upper ridge of high pressure will bring mainly dry, sunny conditions on Saturday. Ridgetop winds light from the West. Freezing levels valley bottom rising to 1800 m by the afternoon. High cloud, and light precipitation expected Sunday. Freezing levels rising to 2500 m, and look to persist through the evening.
Avalanche Summary
No recent observations have been submitted. On Tuesday, avalanche observations include a couple of skier triggered (controlled) size 1.5 loose wet avalanches from East aspects. Wind slabs, loose dry and wet slabs are likely avalanche problems for the weekend to come.
Snowpack Summary
Forecast new snow and wind may build wind slabs on lee slopes and behind terrain features. Recent, spring-like conditions exist, with a melt-freeze crusts on most aspects, with the exemption of higher North facing slopes. Since last weekend, mostly light to locally, low density, moderate amounts of new snow have fallen forming soft slabs on the resulting crust while rain has continued to penetrate and weaken the snowpack at lower elevations. Up to 80cm below the surface, you will find another crust in the alpine and at treeline that may have been reactive (most likely on Southerly aspects) with warming throughout last week. The mid-February buried surface hoar layer is down about 200 cm, although avalanches releasing on this layer represent an extremely low probability-high consequence scenario. Cornices in the region are very large. With spring temperatures, these are more likely to become weak and fail. They could provide a large enough trigger to release deep layers on slopes below. For more information on Spring Conditions and ways to mitigate risk, please visit the new Forecasters Blog Post.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
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.