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

Mar 8th, 2023–Mar 9th, 2023

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

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Moyie.

Continually assess for wind slabs as you move through the terrain. Small pockets of wind slab have been reactive to skier traffic and natural triggers.

Confidence

Moderate

Avalanche Summary

On Tuesday, natural and skier triggered dry loose avalanches were reported to size 1 in steep terrain.

On Sunday and Monday, several natural wind slab avalanches were observed to size 2.5 on westerly aspects between 1800 and 1400 m. These avalanches may have been triggered by cornice fall or strong easterly winds on Saturday night. A skier accidental, size 1.5, wind slab avalanche was reported on a northeast aspect at 1900 m. Check out this MIN from Saturday showcasing the current wind slab problem.

Last week, several skier triggered persistent slab avalanches, up to size 2.5, were reported in the Norns and Rossland region. Many of these avalanches failed on weak layers from February and January and occurred at treeline. Though activity has tapered off on this layer it could still be reactive to large triggers.

Snowpack Summary

40-60 cm of storm snow has been redistributed by shifting winds into wind slabs on all aspects at treeline and above. This storm snow sits over a wind affected layer at all elevations. On open solar aspects, a melt-freeze crust covers the surface.

A layer of surface hoar can be found on shaded slopes, and a sun crust on sun affected slopes buried 40 to 70 cm deep. Another layer from January is buried up to 50 cm below this. These layers were reactive in the Rossland region this week.

The lower snowpack includes a layer of weak sugary crystals near the ground. These facets are slowly gaining strength and have not produced recent avalanche activity. We continue to track the layer and watch for any signs that it could wake up and produce very large avalanches.

Weather Summary

Wednesday Night

Mainly clear with cloudy periods. Southeasterly winds 15-25 km/h. Treeline temperatures, low of -9. Freezing levels drop to valley bottom.

Thursday

Mainly cloudy with sunny periods. Southeasterly winds 10-25 km/h. Treeline temperatures, high of -8. Freezing levels 800 m.

Friday

Cloudy and scattered flurries, 5-7 cm accumulation. Southeast winds 25-40 km/h. Treeline temperatures, high of -7. Freezing levels remain at valley bottom.

Overnight flurries continue 2-5 cm accumulation. Winds switch to the southwest 40-60 km/h.

Saturday

A mix of sun and cloud with isolated flurries, trace accumulation. Southwesterly winds 10-25 km/h. Treeline temperatures, high of -5. Freezing levels 1300 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
  • Approach lee and cross-loaded slopes with caution.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.

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.

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.