Avalanche Forecast

Issued: Jan 13th, 2018 3:08PM

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

istorm, Avalanche Canada

Northwest Coastal.

Significant changes are happening with the arrival of a major warming at higher elevations. How the snow responds is difficult to forecast with precision; however, conditions are worsening so conservative trips and terrain choices are recommended.

Summary

Confidence

High - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A major warming event is starting Saturday mid-day at treeline elevations. For example near Terrace at 1400 m the temperature reached zero degrees around 10:00 AM.SATURDAY NIGHT: Precipitation ending, moderate South wind, and above freezing temperatures at treeline elevations.SUNDAY: Inversion Conditions with warm temperatures around +5 to +8 degrees between 1200 and 2000m; above freezing as high as 2500m. No precipitation with a mix of sun and cloud in the afternoon. Southerly winds in the alpine with easterly outflow in the major valleys.MONDAY: Temperature inversion continues with similar to Sunday but a couple of degrees cooler under some mid and high clouds.TUESDAY: Cooling temperatures with the chance of some new precipitation as the ridge of warm air moves out of the region.

Avalanche Summary

On Friday there were no new reports of avalanches.Avalanche condtions will change with the incoming weather. Major warming near treeline and above will increase the likelihood of avalanches -- both human triggered and releasing naturally.

Snowpack Summary

Wind slabs and storm slabs are found in alpine and at treeline areas on a variety of aspects. Strong outflow winds have formed wind slabs on southerly and southwesterly lee features at all elevations. Southerly winds are driving the incoming weather; although temperatures look so warm that rain is more likely than snow.Up to 45 cm recent snow overlies several layers of interest in the upper snowpack. These include crusts, surface hoar and facets. A hard crust with associated facets from mid-December sits deeper in the snowpack, about 60 cm down. Any of these layers could create a persistent slab problem as new snow, wind-loading or warming change the properties of the slab above.The lower snowpack is generally strong, with the exception of areas around Stewart and further north where a basal crust and facets exist.

Problems

Storm Slabs

New snow, strong winds, warm temperatures, and even rain will likely create touchy slabs and loose wet avalanches

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.Watch open slopes with any steepness over 30 degrees.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

Saturday's wet snow and rain is likely to be followed by continued warm temperatures and sunshine on Sunday.

Use extra caution on solar 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

Persistent Slabs

A weak layer buried about 60 to 80 cm may become reactive with warming temperatures. Shallower slabs may step down to this layer and form large, destructive avalanches.

Back off if you encounter whumpfing, hollow sounds, or shooting cracks.Avoid convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Jan 14th, 2018 2:00PM