Avalanche Forecast

Archived

Feb 21st, 2023–Feb 22nd, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Cariboos, Blue River, Clearwater, McBride, Premier, Quesnel, Sugarbowl, Clemina, North Monashee, Renshaw, Robson.

Expect to find wind slabs on atypical southerly slopes. Remember that any incident in cold weather can be serious.

Confidence

Moderate

Avalanche Summary

We haven't received reports yet from Tuesday but suspect that many storm slab and wind slab avalanches were triggered within the recent storm snow.

Looking forward, the cold weather may mean that newly formed wind slabs could remain human-triggerable for the coming days. These slabs are likely on atypical south to west aspects due to the northeast wind.

Snowpack Summary

Strong northeast wind is redistributing the 50 to 100 cm of recent storm snow into wind slabs on southerly slopes. Very cold weather may allow for these slabs to linger for longer than is typical. All this storm snow may overly a small layer of surface hoar crystals in terrain sheltered from the wind around treeline elevations.

The mid-pack is generally strong with remnants of old weak layers from January, which haven't produced recent avalanches.

Large and weak facets that formed in November are found near the base of the snowpack. Although the likelihood of triggering this layer is low at this time, the consequence of doing so would be high. This layer is most likely to be human-triggered in thin, rocky slopes at alpine and upper treeline elevations.

Weather Summary

Tuesday Night

Mostly clear skies with no precipitation, 30 km/h northeast wind, treeline temperature -25 °C.

Wednesday

Mostly clear skies with no precipitation, 20 km/h northeast wind, treeline temperature -26 °C.

Thursday

Mix of sun and cloud with no precipitation, 20 km/h northeast wind, treeline temperature -26 °C.

Friday

Increasing clouds with no precipitation, 20 to 40 km/h west wind, treeline temperature - 20 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Continue to make conservative terrain choices while the storm snow settles and stabilizes.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.