Avalanche Forecast

Archived

Jan 1st, 2020–Jan 2nd, 2020

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 possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Little Yoho.

More snow and big wind on the way Friday and Saturday. Anticipate having to step back, depending on snow amounts.

Weather Forecast

Wind, warm temps and snow starting early Friday. By Saturday end of day there could be up to 25cm of storm snow, as indicated by the weather models. The accompanying wind will be from the SW and could reach extreme values.

Snowpack Summary

Thin/soft windslabs forming on the surface near ridge top from light NW wind and 5-10 cm overnight. In most areas the upper snowpack of denser snow sits over a weak mid and lower snowpack consisting of facets, depth hoar and crusts. In deeper snowpack areas these weaknesses are less pronounced. Snowpack depths at treeline average 100-160 cm.

Avalanche Summary

No new natural avalanches observed or reported.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Friday

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.