Avalanche Forecast

Archived

Feb 20th, 2019–Feb 21st, 2019

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 unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Cariboos.

Though avalanche activity has slowed down, it is worth keeping in mind that the potential still exists for humans to trigger persistent slab avalanches. While these avalanches are becoming less likely, the consequences remain high.

Confidence

High -

Weather Forecast

WEDNESDAY NIGHT - Mainly clear / north winds 10-20 km/h / alpine low temperature near -18THURSDAY - Mainly sunny / southwest winds 10-20 km/h / alpine high temperature near -12FRIDAY - Mainly cloudy with flurries, 5 cm / south wind 15-35 km/h / alpine high temperature near -13SATURDAY - A mix of sun and cloud with isolated flurries / northeast winds, 15-35 km/h / alpine high temperature near -14

Avalanche Summary

No new slab avalanches have been reported since Saturday. Several loose avalanches to size 1 have been reported recently.On Saturday, a persistent slab avalanche was triggered by a skier on a north aspect on a 30 degree slope. Check out the MIN report here. These sorts of avalanches are becoming less frequent, but they are still possible and the consequences are high.There was also evidence of large avalanches (up to size 3) that were triggered by strong wind in the north of the region on Saturday.On Friday, two more small to large (size 1 to 2) persistent slab avalanches were triggered by humans. They were 50 to 70 cm deep and released on the mid-January surface hoar layer described in the Snowpack Summary. They occurred at treeline and alpine elevations on north to northwest aspects.

Snowpack Summary

Depending on location, the snow surface varies from 10-30 cm of low density snow, to hard wind slab with softer wind slabs in the mix as well. Winds have been from a variety of directions, so wind slabs may be found on all aspects, mainly in the alpine and at treeline.A weak layer that was buried in mid January is now buried anywhere from 30-60 cm. This layer consists of surface hoar (feathery crystals) and facets (sugary snow). The layer also likely consists of a crust on south facing slopes. Avalanche activity on this layer has slowed, but test results still indicate that this layer may still be easy for humans to trigger in certain locations. It has been most reactive at treeline and below treeline.The lower snowpack is considered generally strong.

Problems

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.