Avalanche Forecast

Archived

Mar 18th, 2020–Mar 19th, 2020

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

South Coast Inland.

Warm sunny weather continues. Use increased caution when slopes and cornices warm up throughout the day.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

A high pressure system brings clear dry conditions for the foreseeable future.

WEDNESDAY NIGHT: Clear skies, calm, freezing level drops to valley bottom, alpine temperatures drop to -8 C.

THURSDAY: Sunny, light wind, freezing level climbing to 1800 m in the afternoon, alpine high temperatures around -3 C.

FRIDAY: Sunny, light northwest wind, freezing level climbing to 2000 m in the afternoon, alpine high temperatures around -2 C.

SATURDAY: Mix of sun and cloud, light to moderate northwest wind, freezing level climbing to 1500 m in the afternoon, alpine high temperatures around -3 C.

Avalanche Summary

Warm sunny weather over the past few days has resulted in several wet loose avalanches on south-facing slopes across the region (see a photo in this MIN report). One natural size 2 slab was observed on a northeast alpine slope in the northern part of the region on Monday. Some large glide slab releases have been reported around the Coquihalla.

Looking forward, daily warming will likely cause more wet loose avalanches and potentially weaken cornices and lingering wind slabs. In northern parts of the region, the warming trend has potential for the deep persistent slab problem to reawaken.

Snowpack Summary

Surface conditions are highly variable with a mix of crusts, moist snow, and hard wind slabs. The surface will become moist on sun-exposed slopes and at lower elevations throughout the day.

In the northern part of the region (i.e. Duffey/Hurley/Gold Bridge), a deep instability may linger at the base of the snowpack. It has not produced an avalanche since Feb 17, but could still possibly be triggered on shallow rocky slopes or from large cornice falls.

Terrain and Travel

Back off slopes as the surface becomes moist or wet with rising temperatures.
Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
Carefully evaluate steep lines for wind slabs.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.