Avalanche Bulletin - Northwest Inland

Date Issued:

Valid Until:

Forecaster:ahanna

Thin, soft slabs from recent snowfall will likely continue to be reactive to human triggering, especially in wind sheltered areas at and below treeline where they sit over weak facets.

Tue, 21 JanWed, 22 JanThu, 23 Jan
Alpine2 Moderate2 Moderate2 Moderate
Treeline2 Moderate2 Moderate2 Moderate
Below Treeline1 Low1 Low1 Low
Confidence: Moderate

Travel and Terrain Advice

Wind Slab

Southerly winds are forming fresh windslabs from 10-20 cm of recent snow in places that were previously scoured by northeasterly arctic outflows.

Deep Persistent Slab

A deep facet/crust layer from November lurks at the base of the snowpack. It has produced infrequent but very large avalanches in lee and cross-loaded alpine terrain.

Forecast Details

Avalanche Summary

Over the weekend, a natural storm cycle was observed in the Howson ranges, at treeline and below. Slabs were soft and thin but propagated widely resulting in avalanches up to size 2. They ran on the faceted interface buried January 17th.

As recently as Saturday, we have received reports of windslab avalanches size 1.5-2.5 mostly around treeline. Crown depths have been up to 1 m, running on a layer of surface hoar layer buried on January 10th.

There have been reports trickling in of natural persistent slab avalanches up to size 3 in the Bulkley Valley. These are thought to have been failing on the November crust/facet layer near the ground. The last reported activity at this interface was Monday January 13th. 

Snowpack Summary

Extensive wind effect at all elevations is well illustrated in photos from this MIN post from Saturday. Southerly winds are forming fresh windslabs from 10-20 cm of recent snow in places that were previously scoured by northeasterly arctic outflows. In wind sheltered areas at treeline and below, the recent snow sits on a layer of touchy facets.

A layer of surface hoar up to 1 m in depth may also be found at treeline. A deep crust/facet layer lurks at the base of the snowpack. A couple of large avalanches are suspected to have run on this interface in the last few weeks. These larger avalanches have been specific to lee and cross-loaded features in the alpine.

Weather Forecast

Monday night: Mostly cloudy with isolated flurries bringing a trace of new snow. Light southwest winds. Alpine low -7 C.

Tuesday: Mostly cloudy with isolated flurries bringing a trace of new snow. Moderate southeast winds. Alpine high -6 C.

Wednesday: Mix of sun and cloud with isolated flurries bringing a trace of new snow. Moderate south to southwest winds, strong at ridgetop. Alpine high -8 C.

Thursday: Mostly cloudy with scattered flurries bringing up to 5 cm overnight followed by 5 cm over the day. Moderate southwest winds, strong at ridgetop. Alpine high -5 C.