Avalanche Forecast

Issued: Jan 15th, 2013 9:45AM

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

ccampbell, Avalanche Canada

South Coast.

Summary

Confidence

Fair

Weather Forecast

Wednesday: Mostly clear with valley cloud possible in the morning. A temperature inversion is expected to bring treeline and alpine temperatures above freezing, while lower elevations should stay cold. Winds should be light to moderate from the northwest. Thursday: Low cloud in the morning changing to a mix of sun and cloud throughout the day as the temperature inversion weakens and lower elevations start to warm up with freezing levels as high as 2500m. Light to moderate northwesterly winds shifting to westerlies in the afternoon. Friday: A mix of sun and cloud and dry throughout the day. Freezing levels remaining at around 2500m.

Avalanche Summary

Recent observations include snowballing and several wet loose sluffs ip to Size 1.5 on sun-exposed slopes. A few large slab avalanches up to Size 3, involving the persistent weakness buried at the beginning of January also released due to intense warming on south aspects on Monday. Check out this incident report from the Duffey Lake area on the weekend. The 60cm deep slab avalanche may have release on the surface hoar persistent weakness buried at the beginning of the month.

Snowpack Summary

Above freezing temperatures at higher elevations caused snow surface moistening on on sun-exposed slopes, breaking down the 1-2cm surface crust, and weakening wind slabs. The surface snow on northerly aspects has been remaining dry with continued surface hoar growth. Below this, 40-80 cm of settling storm snow sits on a persistent weakness of buried surface hoar, facetted snow, and /or a crust. Recent snowpack tests show that this interface is gaining strength but is likely still susceptible to human triggering with potential to propagate widely. No significant weaknesses have been reported recently below this in the mid snowpack layers. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in steep, shallow, rocky terrain where more facetting has taken place.

Problems

Persistent Slabs

A buried weakness, down 40-80 cm, has been active as a result of intense daytime warming.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Wind Slabs

Strong northerly winds have produced new wind slabs in exposed lee and cross-loaded terrain.

Be cautious as you transition into wind affected terrain.>Avoid freshly wind loaded features.>Avoid travelling in areas that have been reverse loaded by winds.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Loose Wet

Loose wet activity is expected as temperatures rise. A loose wet slide could step down and trigger weaknesses deeper in the snowpack.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Jan 16th, 2013 2:00PM