Avalanche Forecast

Archived

Feb 1st, 2019–Feb 2nd, 2019

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.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Glacier.

A widespread natural avalanche cycle is underway and storm conditions will persist until Saturday afternoon.

Weather Forecast

A low pressure system is stalling over the area for the next 2 days bringing another 35cm of new snow by Saturday afternoon. Freezing levels rise to 1300m today with an alpine high of -5 and ridge winds SW 35km/h. A transition to high pressure on Saturday evening will usher in frigid temperatures reaching a low of -26 on Sunday.

Snowpack Summary

35cm of new snow has fallen in the past 24hrs with moderate south winds. New snow sits atop hard wind slabs in the alpine. The January 17 surface hoar is buried 60cm and is most reactive between 1400-1900m, and where it overlies a crust on steep solar aspects. Several crusts exist in the upper snowpack on steep south aspects.

Avalanche Summary

A small natural avalanche cycle began yesterday with the arrival of the storm front. This morning larger avalanches (size 2-3) were observed in the highway corridor. Natural avalanche activity is expected to persist for the next 2 days as the storm snow continues to accumulate.

Confidence

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.