Avalanche Forecast

Issued: Apr 19th, 2016 8:00AM

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

triley, Avalanche Canada

Northwest Coastal.

Spring Conditions. Expect the likelihood of wet slab and loose wet avalanches to increase during the heat of the day. Watch for clues like snowballing that the surface is heating up and the snowpack may be losing strength.

Summary

Weather Forecast

Clear overnight with freezing down to at least 1000 metres. Moderate southerly winds on Wednesday with clear skies and freezing levels up to 2500 metres. Mostly clear on Thursday with moderate southeast winds and cloud developing in the late afternoon. Freezing level up to 3000 metres on Thursday. Cloudy and cooler on Friday with freezing levels around 2000 metres and moderate to strong southeast winds.

Avalanche Summary

Numerous wet slab avalanches up to size 3.0 were reported from near Stewart in the 1400-1600 metre elevation band. Most of these avalanches were triggered by explosives and they were about 50 cm deep.

Snowpack Summary

Clearing and cooling overnight has re-frozen the upper snowpack down to about 700 metres. Previously, there was 20-40 mm of precipitation in the past few days. Most of this has fallen as rain up to about 1800 metres. Most of the precipitation has been in the near coastal ranges, with Stewart and Kitimat receiving closer to 40mm and areas around Terrace closer to 20mm. Winds have been strong out of the south; reports from Stewart of gusts above 100 km/hr on Monday that have developed wind slabs in the high alpine. Rain has soaked the snowpack at lower elevations. Some recent crusts within the upper snowpack may continue to provide a sliding layer for loose wet avalanches when forecast temperatures and freezing levels spike in the next few days.

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.

Plan to be off big slopes before the temperatures rises and the snowpack deteriorates.>Be aware of the potential for large, deep avalanches.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

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.

Look for signs of surface instabilities such as pinwheeling and point releasing near cliffs.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Wind Slabs

Recent wind slabs should settle and bond overnight with overnight freezing levels dropping after a warm day. Some shaded north aspects may hold dry wind transported snow that may be easy to trigger.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid freshly wind loaded features.>Be alert to conditions that change with elevation.>

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 20th, 2016 2:00PM