Recent avalanche activity in the Dogtooth Range suggests the avalanche danger may be higher in northern parts of the region.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
FRIDAY: Mainly cloudy, Light southwesterly winds, and freezing levels in valley bottoms with alpine temperatures reaching -5 C.SATURDAY: Mainly cloudy with light westerly winds, and freezing levels rising as high as 2200 m in the evening.SUNDAY: Mainly Cloudy with light rain/snow possible, strong southwesterly winds and freezing levels hovering around 2200 m.
Avalanche Summary
Reports from Monday include 2 skier-triggered size 2 wind slab avalanches in the Dogtooth Range. Buried surface hoar beneath the 35 cm thick wind slab is expected to have increased the reactivity of the avalanches which ultimately stepped down to the deeper mid-December facet layer. One avalanche occurred on a northeast aspect while the other occurred on a west aspect. They were both, however, cross-loaded alpine features. Reports from Tuesday include several explosives-triggered Size 2 persistent slab avalanches in cliffy terrain propagating as far as 40m across the slope and stepping down to facets and depth hoar near the ground. No significant avalanches were reported on Wednesday. Moving forward, lingering wind slabs are expected to remain a concern, especially where the slabs sit over a preserved layer of surface hoar.
Snowpack Summary
20-50 cm of recent snow is settling over the previous mid-January snow surface which includes buried surface hoar in sheltered areas, and/or widespread facets. This slab is particularly touchy where where the buried surface hoar is preserved. Southwest winds have deposited wind slabs on the downwind side of ridge crests and similar terrain features. Another surface hoar/facet persistent weakness that was buried mid-December, can now be found down 50-100 cm and is generally considered dormant. However, a few storm slab and wind slab avalanches have recently stepped down to this layer in isolated areas. This layer remains an isolated concern for shallow snowpack areas where the layer is closer to the snow surface. With the next storm or period of warming, this layer could wake up and create a more widespread problem.
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.