Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Feb 3rd, 2018–Feb 4th, 2018

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Rockies.

Another pulse of snow and wind will create dangerous conditions at higher elevations. Stick to small supported terrain features and avoid overhead hazards.

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The weather in this region will strongly depend on the position of the Arctic front that is pushing in from Alberta. Areas east of the front will have much colder temperatures and potentially heavy accumulations while areas west of the front will be warmer and receive less snow.SUNDAY: Snow increasing throughout the day with localized heavy accumulations (5-20 cm), strong west wind, alpine high temperatures around -7 C.MONDAY: Mix of sun and cloud with isolated flurries, strong northwest wind east of the divide, cold Arctic air returns with alpine high temperatures around -10 C.TUESDAY: Cloudy with scattered flurries, strong west wind, alpine high temperatures around -5 C.

Avalanche Summary

Reports are limited, but there was one explosive triggered wind slab avalanche east of the divide on Saturday. There was likely natural wind slab activity in the northeast part of the region where the heaviest accumulations occurred.On Friday, a snowmobiler was partially buried by a size 2 avalanche in the Alexander Creek drainage. The avalanche occurred on a north aspect around 2000 m and failed on weak snow near the ground. See report here. A few small wind slabs were triggered by skiers in lee terrain on Thursday and Friday.A few large persistent slab avalanches that released during last weekend's storm were observed last week as well. These avalanches failed on deep weak layers from November and December, resulting in large avalanches (size 3). Most were triggered by cornices falling on north and east facing slopes. The incoming storm has potential to trigger similar large avalanches.

Snowpack Summary

An upslope storm delivered lots of cold low density snow east of the divide on Saturday (20-30 cm). The distribution of new snow is highly variable, and so are the surface snow conditions. The western parts of the region in BC were relatively warm with less snow, while areas in Alberta and around the divide were much colder and windier which likely formed touchy wind slabs in open terrain.The lower snowpack in this region is weak, with a number of concerning weak layers. A layer buried mid-January is composed of surface hoar on sheltered aspects and a sun crust on solar aspects was and is now 30-50 cm deep. Another surface hoar layer from early-January is buried 40-60 cm deep. A widespread weak layer from mid-December composed of facets, crusts, and surface hoar is 60-80 cm deep. Finally, a rain crust with sugary facets buried in late-November is near the bottom of the snowpack. Although the snowpack structure is variable across the region, these persistent weak layers are generally widespread.

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.

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.