Avalanche Forecast

Archived

Mar 27th, 2020–Mar 28th, 2020

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Regions

South Coast.

Intense snowfall, heavy rain, and strong winds will create dangerous avalanche conditions.

Confidence

Low - Uncertainty is due to limitations in the field data.

Weather Forecast

Friday night: Cloudy, 10-20 cm of new snow above 1300 m, moderate southwest wind, treeline temperatures near 0 C.

Saturday: Cloudy, 30-40 cm of new snow above 1300 m, strong southwest wind, freezing level climbing to 1400 m in the afternoon, treeline temperatures reach 0 C.

Sunday: Mostly cloudy, 30-40 cm of new snow overnight, moderate southwest wind, freezing level dropping to 1000 m, treeline temperatures reach -2 C.

Monday: Mostly cloudy, 20-30 cm of new snow, moderate southwest wind, freezing level dropping to 800 m, treeline temperatures reach -5 C.

Avalanche Summary

Slab avalanches are a concern on slopes with accumulations of new snow, especially in wind-loaded terrain. Wet loose avalanches are expected on steep slopes at lower elevations. No recent avalanches have been reported, but mountain travel and field observations have been very limited.

Snowpack Summary

A powerful storm is bringing intense snowfall, heavy rain, and strong southwest winds to the region. At higher elevations, snowfall accumulations in the 30-40 cm range are expected to build widespread, reactive storm slabs and create dangerous avalanche conditions. Heavy rain is expected to rapidly saturate the surface snow at lower elevations.

15-25 cm of snow from earlier in the week covers a variety of snow surfaces including crusts, warm snow, and wind-affected snow. There is some uncertainty about how well the new snow has bonded to these interfaces. The snowpack is well-settled. Snowpack depths diminish rapidly with elevation, with 300-400 cm at treeline and no snow below 700 m.

Terrain and Travel

Storm slab size and sensitivity to triggering will likely increase through the day.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

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.

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.