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Avalanche Forecast

Apr 19th, 2016–Apr 20th, 2016
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: Sea To Sky.

Spring Conditions. Record breaking warm weather continues. Expect the likelihood of wet slab avalanches, cornice falls, and loose wet avalanches to increase during the heat of the day.

Weather Forecast

Clear overnight with light southwest winds and freezing levels around 2000 metres. Clear and sunny on Wednesday with light winds and daytime freezing up to 3500 metres. Cloud developing on Thursday morning with light southwest winds and freezing levels climbing to 3000 metres during the day. Cloudy with convective showers and snow flurries on Friday and the freezing level at 2500 metres.

Avalanche Summary

We have a MIN report of a close call with a size 2.5 wet slab avalanche on a northeast aspect in the alpine on Hour Peak on the McBride range traverse. A skier triggered the large avalanche that released down 30 cm on an old melt-freeze crust and propagated a fracture about 50 metres wide. Most commercial operations in the region have finished their season and data is becoming sparse.

Snowpack Summary

Cornices remain a concern, in part because of the potential to trigger wet slab avalanches that run to valley bottoms. Monitoring the overnight freeze of the snow surface is very important. If the snow surface does not freeze overnight or if the crust is only a few cm thick, the effect of daytime heating and solar radiation will weaken the snowpack much more quickly than it would if there is a well frozen thick crust. This is because the crust must first melt before the sun can weaken the snowpack. With the warmest weather this year forecast, layers in the mid snowpack and near the ground have the potential to wake up and become active. While isolated and unlikely, avalanches could be very large. Glide cracks are widespread, active, and best avoided. Low elevation and thin snowpack areas have become isothermal, meaning the snowpack is 0 degrees Celsius throughout. An isothermal snowpack is more prone to full depth wet slab avalanches during the heat of the day, especially on steep, rocky faces.

Avalanche Problems

Wet Slabs

The likelihood of wet slab avalanches will increase with forecast high freezing levels and strong solar radiation. Areas that do not re-freeze overnight may become very weak early in the day.
Avoid sun exposed slopes, especially where the snow is wet, weak, and mushy.>Avoid rocky, shallow or steep slopes during the heat of the day.>Travel early before the heat of the day, and avoid big slopes in the afternoon.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 6

Loose Wet

Sunny skies and high freezing levels will weaken the surface snow on solar aspects. Shaded aspects in the alpine may warm up enough to release as loose wet avalanches.
Start and finish early before the surface crusts melt.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Cornices

Strong solar radiation and little or no overnight freeze will continue to weaken cornices. Avoid travel beneath cornices.
Cornices become weak with daytime heating. >Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5