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

Jan 21st, 2023–Jan 22nd, 2023

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

Regions

Purcells, Esplanade, Dogtooth, East Purcell, West Purcell.

A complex snowpack continues to produce large and destructive avalanches.

Use conservative terrain choices and have a 'plan B' to avoid areas with a thin snowpack.

Confidence

Moderate

Avalanche Summary

Since Thursday there have been many avalanches in our area that have reached up to size 3.5 (very large). They have been triggered naturally but also with explosives and ski cuts. Many of these avalanches have been from storm slabs, wind slabs, as well as persistent and deep persistent slabs.

The varied size and characteristics of recent avalanches have been due to the complexity of the snowpack. These instabilities will remain with us for the foreseeable future and use of caution when traveling through the backcountry is advised.

Snowpack Summary

Recent storm snow, 15 to 25 cm, can be found in sheltered areas, while open terrain has been wind affected. The recent snow overlies a mid-January interface that includes small surface hoar all the way into the alpine in some parts of the region as well as a rain crust, that reaches up to 2000 m, which can be found in most but not all areas of the region.

There are two additional weak layers in the top metre of the snowpack. The first is down 30 to 50 cm and is a layer of surface hoar from early January. The second is a layer of surface hoar, facets, and a crust from December, down 40 to 90 cm. The surface hoar is most prevalent in sheltered areas while crusts and any associated faceted snow are more widespread.

The bottom of the snowpack contains yet more weak, faceted snow. Large avalanches continue to be produced from this weak snow and will likely persist for the time being.

All of these interfaces are at their shallowest in the east of the region and all of them have produced avalanches recently.

In general, the snowpack is shallow and weak throughout our region with 80 to 180 cm sitting on the ground at treeline and alpine.

Weather Summary

Saturday Night

Increasing cloud, up to 5 cm accumulation in western sections, 8 to 20 km/h southwest wind, alpine temperatures -10 C.

Sunday

Sunny with cloudy periods, trace accumulation, 25 km/h northwest winds, alpine high of -10 C.

Monday

Mostly sunny, trace accumulation, 34 km/h southwest wind, alpine temperatures -10 C.

Tuesday

A mix of sun and cloud, no accumulation, 20 km/h west wind, alpine temperatures -8 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

Problems

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.

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.

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.