Archived

Avalanche Forecast

Jan 24th, 2015–Jan 25th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Tricky snowpack conditions right now, which vary across the region. Conservative decision-making will be essential.

Confidence

Poor - Freezing levels are uncertain

Weather Forecast

Rainfall peters out on Sunday morning and temperatures remain unseasonably warm through Monday, with the freezing level climbing to 3300 m. On Tuesday, we expect a brief pulse of light rain turning to light snow. The freezing level drops to around 800 m. Winds are moderate SW for the next three days.

Avalanche Summary

Several naturally-triggered loose wet avalanches were observed below 1750 m at Kootenay Pass on Saturday. Skiers triggered size 1 -1.5 storm slabs on Friday at treeline elevations. These failed on the Jan surface hoar layer buried about 30 cm below the surface.

Snowpack Summary

Up to 15cm new snow (likely shifted by strong W- SW winds into deeper slabs on lee aspects) overlies various surfaces including surface hoar, a thin crust, or a settled slab. Around Kootenay Pass, a freezing rain crust formed above 1750m on Saturday, getting stronger and thicker with increasing elevation. In other areas, warm temperatures may affect the upper snowpack and increase the storm slab problem, which could be touchy above the mid-Jan surface hoar layer (down about 40-60 cm). These large, well-preserved surface hoar crystals sit on a thin crust up to about 1900m on north aspects and all the way to ridgeline on south aspects. A deeper crust/surface hoar combo buried in mid-December continues to be a concern. This layer is typically down 80-100cm and has produced some large avalanches recently. All in all it sounds like a pretty variable and possibly troublesome snowpack. A good time to do some digging and venture gently.

Avalanche Problems

Persistent Slabs

Warming temperatures can increase the reactivity of persistent slabs and storm slabs, which overlie a touchy weak layer of buried surface hoar.

Avoid freshly wind loaded features.>Choose well supported terrain without convexities.>Stick to small features with limited consequence.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Loose Wet

Very warm temperatures and a bit of rain are expected to weaken the recent storm snow and create loose wet avalanches in steep terrain.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be aware of party members below you that may be exposed to your sluffs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Deep Persistent Slabs

A weak layer is now buried about a metre down. It has the potential to cause very large avalanches if triggered.

Avoid common trigger points such as convexities, thin or variable snowpack areas and around rocks.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 3 - 6