Archived

Avalanche Forecast

Mar 4th, 2017–Mar 5th, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

A few days of cool benign weather. Concerns include wind slabs at higher elevations and the ongoing potential to trigger deep persistent slabs in shallow snowpack areas.

Confidence

High - The weather pattern is stable

Weather Forecast

SUNDAY: Cloudy with sunny periods, light south winds, alpine temperatures around -17 C.MONDAY: Cloudy with isolated flurries and trave amounts of new snow, moderate south winds, alpine temperatures around -15 C.TUESDAY: Scattered flurries with 5-10 cm of new snow, moderate south winds, alpine temperatures around -15 C.

Avalanche Summary

On Friday, several size 1-2 natural wind slabs were reported in both the Telkwas and Sinclair areas on north and east aspects. The avalanches likely occurred during the storm on Thursday. A few small size 1 slab and loose dry avalanches running on a crust were skier triggered in steep low elevation terrain. Isolated wind slabs may still be found in alpine locations on leeward slopes behind terrain features.

Snowpack Summary

Recent low density storm snow up to 25 cm has fallen with some wind effect at higher elevations. The new snow buried a variety of old snow surfaces including stiff wind slabs, facets, crusts and surface hoar. The new snow may have a poor bond to these interfaces, especially in places where the slab is stiffer and more cohesive due to winds. At treeline elevations the average snowpack depths are 120-190 cm and a well consolidated mid-pack of approximately up to 100 cm sits above weak basal facets (sugary snow) near the ground. Recent snowpack testing has shown sudden easy results down 25 cm on a surface hoar layer and sudden hard results down 100 cm within the faceted snow. The deeper basal weakness remain a concern, especially in thin rocky start zones and shallow snowpack locations.

Avalanche Problems

Wind Slabs

Gusty southwest winds at upper elevations have formed fresh wind slabs on leeward slopes and behind terrain features. Loose dry avalanches may be easily triggered below treeline or in areas sheltered from the wind.

Sheltered slopes will likely offer the best skiing today.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

A lingering weakness at the bottom of the snowpack may remain sensitive to human triggering, especially in shallow snowpack areas. Smaller avalanches in motion also have the potential to step down and trigger deep persistent slabs.

Avoid steep convexities or areas with a thin or variable snowpack.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3