Regions
Northwest Inland.
Very strong winds are expected with the approaching weather system. These winds could also push more snow into the Inland region than initially expected. As such, danger is elevated for Thursday.
Confidence
Moderate - Forecast snowfall amounts are uncertain on Thursday
Weather Forecast
THURSDAY: Periods of snow – 10-20 cm. The freezing level peaks near 1400 m but gradually lowers to valley bottom by the end of the day. Winds are strong from the W-SW. FRIDAY: Cloudy with sunny breaks. The freezing level is around 1200 m and winds are light to moderate from the SE. SATURDAY: Cloudy with sunny breaks. The freezing level is around 1000-1200 m and winds are light from the SE.
Avalanche Summary
There were no new reports of avalanches on Tuesday. A couple natural size 2 wind slabs were observed on immediate lee alpine slopes on Monday. One size 3 natural storm slab was observed in the Southwest corner of the region on Sunday. This slide probably occurred 1-2 days earlier. It released on a northeast aspect in the alpine. There were a handful of large persistent slab avalanches triggered on basal facets in the mountains north of Kispiox last week.
Snowpack Summary
Roughly 20-40 cm of snow has fallen in the past week, with the highest accumulations occurring in the southwest of the region. Strong to extreme ridgetop winds have shifted the new snow into hard or soft wind slabs in exposed terrain, adding to an ongoing wind slab problem. A layer of surface hoar from early January can be found in isolated locations between 60 and 140 cm down. There hasn't been any activity reported on this layer for a couple of weeks now and it is becoming less of a concern. In shallower areas the snowpack sits on a weak base layer of facetted snow. Recently, this layer has been active in the north of the region, responsible for several large avalanches in unsupported alpine terrain.
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.