Avalanche Forecast

Archived

Mar 28th, 2020–Mar 30th, 2020

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Rockies.

This forecast lacks field observations and has lots of uncertainty. This will be the last avalanche forecast of the season. Reactive wind slabs remain the primary concern, especially around ridge features and wind loaded terrain.

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

Saturday night: Cloudy with isolated flurries, trace to 5 cm. Alpine low temperature -6 C. Moderate to strong southwest wind. Freezing level to valley bottom.

Sunday: Cloudy with scattered flurries, trace to 10 cm. Alpine high temperature -1 C. Moderate gusting to strong southwest wind. Freezing level 1900 m.

Monday: Flurries, 5-15 cm. Alpine high temperature -6 C. Moderate gusty southwest wind. Freezing level 1700 m and dropping.

Tuesday: Cloudy with scattered flurries, 5-10 cm. Alpine high temperature -10 C. Light east wind. Freezing level valley bottom.

Avalanche Summary

We have very limited field observations at this time. There have be no new avalanches reported in the region.

Snowpack Summary

Recent snow has been impacted by wind and warm temperatures. Cold, dry snow persists at higher elevations and consists of a variety of wind affected surfaces and a crust on sun-exposed slopes. A crust is on steep solar slopes and below tree line.

A layer of faceted grains down 40-80 cm overly a melt-freeze crust from early February. The base of the snowpack contains basal facets that are most prominent in shallow, rocky start zones.

Terrain and Travel

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.