Archived

Avalanche Forecast

Dec 6th, 2017–Dec 7th, 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

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

Avoid south slopes. They have been wind loaded and will become weak with the intense warming and sun.

Confidence

High - The weather pattern is stable

Weather Forecast

THURSDAY: Alpine sun with some valley clouds, light northwest wind, freezing level around 3300 m with inversions in the valleys.FRIDAY: Alpine sun with some valley clouds, light northwest wind, freezing level around 3000 m with inversions in the valleys.SATURDAY: Increasing cloud, moderate west wind, freezing level around 2700 m with inversions in the valleys.

Avalanche Summary

On Tuesday, a small (size 1) natural storm slab avalanche was reported on a southeast slope at 2150 m. Previous activity from the weekend included some larger natural and skier triggered storm slabs up to size 2, with the largest cause by recent loading from northwest winds.

Snowpack Summary

Dramatic warming will cause widespread melting of the surface snow, especially on south-facing slopes. Crusts may form overnight, but will melt quickly in the mornings. 30 - 50 cm of new snow has fallen in the past week. At higher elevations, northwest winds redistributed the snow, forming wind slabs on downwind (lee) features. Below the recent storm snow you'll likely find a couple of widespread crusts (2 to 5 cm thick) which formed as a result of late November's rain. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 100-170 cm in the alpine, 50-100 cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks.

Avalanche Problems

Loose Wet

Conditions will be more like spring than winter starting Wednesday. Surface snow layers can become weak when hit by the sun. Minimize your exposure to terrain traps - even small sluffs can push you into dangerous terrain.

Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Use extra caution on sunny slopes or if the snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Wind Slabs

Winds from the northwest have formed hard slabs on south and east facing slopes. Be careful on steep convex terrain or where the wind has blown the snow into more cohesive slabs.

Be alert to changing snow conditions, especially where the snow firms up or sounds hollow.Be careful with wind loaded pockets on downwind (south east facing) slopes.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2