Avalanche Forecast

Issued: Jan 24th, 2015 8:09AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Persistent Slabs, Loose Wet and Deep Persistent Slabs.

pgoddard, Avalanche Canada

Kootenay Boundary.

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

Summary

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.

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

Valid until: Jan 25th, 2015 2:00PM