Avalanche Forecast

Issued: Jan 18th, 2015 7:20AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs and Storm Slabs.

pgoddard, Avalanche Canada

Sea To Sky.

Give the recent snow a day or two to find its equilibrium before venturing into exposed avalanche terrain.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain on Wednesday

Weather Forecast

A weak ridge provides a break from heavy precipitation, but doesn't bring clear skies, through Monday and Tuesday. The freezing level hovers near 900 m and SW winds are light to moderate. On Wednesday, 10-15 cm snow is expected, with gradually warming temperatures.

Avalanche Summary

On Saturday, skiers triggered numerous small storm slabs and wind slabs were reportedly failing naturally to size 2. Natural activity probably peaked during the storm on Saturday night/Sunday, and remains possible on Monday.

Snowpack Summary

Two recent pulses of snow accompanied by strong S-SW winds have built deep wind slabs above a hard crust and/or surface hoar. The buried crust is most pronounced between about 1500 m and 2200 m. The distribution of the surface hoar seems spotty across the region, but some operators found it to be widespread in their tenure before the snow began burying it. Where the surface hoar exists, whumpfing indicates the touchiness of this interface. Deeper snowpack weaknesses (curst/facet and/or surface hoar layers formed in November and December) have fallen off the radar, but they could be reawakened with a very heavy load (like a cornice fall or wind slab) in the wrong spot (like a thin snowpack area, or high elevation northerly aspects where there is no strong crust above).

Problems

Wind Slabs

Recent winds have left deep, hard wind slabs on lee slopes which could be triggered by the weight of a person.

Give cornices a wide berth when travelling on or below ridges.>Travel on ridgetops to avoid wind slabs on slopes below.>Back off if you encounter any cracking or whumpfing.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 5

Storm Slabs

New snow has built up over weak old surfaces, forming a poor bond.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Jan 19th, 2015 2:00PM