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 19th, 2023–Feb 20th, 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 and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

North Columbia, South Columbia, Esplanade, Jordan, North Selkirk, Shuswap, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, North Okanagan, Retallack, Valhalla, Whatshan.

Storm slabs will likely remain reactive with continued snow and wind. Continually assess for changing conditions, and stick to low-consequence terrain, while avoiding large avalanche paths and overhead hazards like cornices.

Confidence

Moderate

Avalanche Summary

Several storm and wind slab avalanches (sizes 1 to 2) were reported on Saturday, mostly in alpine terrain on a variety of aspects.

1 large, size 3.5, natural, deep persistent slab avalanche was observed in the western Purcells. This occurred in large alpine terrain at roughly 2750 m.

On Friday, a naturally triggered size 2 persistent slab that likely failed on a crust down around 100 cm was reported on a west aspect below treeline near Joss mountain.

Snowpack Summary

Roughly 50 to 70 cm of new snow has fallen since late last week. The recent snow is settling into storm slabs that will be most reactive where either wind has stiffened the snow or they overlie a layer of recently buried surface hoar.

The mid-pack is generally well consolidated with a few operations reporting continued snowpack results on a spotty surface hoar layer down roughly 80 cm. Reports of large avalanches involving various layers of surface hoar/crusts and facets within the mid-pack depth are sporadic but are a reminder of the complicated snowpack across this region.

In the lower snowpack, a layer of large and weak facets from November near the base of the snowpack is slowly gaining strength but there continues to be low confidence in this layer. Large destructive avalanches are the result of this layer being triggered.

Weather Summary

Sunday night

Cloudy and light snow, 2 to 7 cm. Moderate westerly alpine winds. Treeline temperature around -5 C.

Monday

Cloudy with snow, 5 to 10 cm. Light to moderate westerly alpine winds. Treeline temperatures 0 to -5 C.

Tuesday

Heavier snow begins Monday night into Tuesday, 10 to 25 cm. Light to moderate northeast alpine winds. Treeline temperatures dropping to around -15 C by day's end.

Wednesday

Cloudy with sunny periods, no precipitation. Light northeast alpine winds. Treeline temperatures -15 to -20 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Expect slab conditions to change drastically as you move into wind exposed terrain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Use small low consequence slopes to test the bond of the new snow.

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.

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.