Archived

Avalanche Forecast

Apr 1st, 2018–Apr 2nd, 2018

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: North Columbia.

Avalanche activity over the course of the storm has been extensive. Maintain conservative terrain selection while human-triggering remains a concern. Isolated areas will see storm slabs continue to build over Sunday night.

Confidence

Moderate -

Weather Forecast

Monday: A mix of sun and cloud with isolated flurries and a trace of new snow. Light variable winds. Alpine high temperatures around -10.Tuesday: Mainly cloudy with isolated flurries and a trace to 3 cm of new snow. Light southwest winds. Alpine high temperatures around -9Wednesday: Mainly cloudy with isolated flurries and a trace of new snow, increasing overnight. Light southeast winds. Alpine high temperatures around -6.

Avalanche Summary

Reports from Saturday included numerous observations of storm slabs releasing naturally as well as with remote (from a distance) triggering, skier traffic and explosives control. Sizes ranged from 2-3, with crown fracture depths varying from 30-100 cm. This activity occurred on all aspects but was focused at alpine elevations.Friday's storm caused a natural avalanche cycle with numerous size 1-2 avalanches in the top 20-30 cm of new snow. Storm slabs were also reactive to skiers, producing several size 1 avalanches on small terrain features on various aspects.Storm slab avalanches have been reported on a regular basis since Tuesday's storm. Natural avalanches up to size 3 were reported from Tuesday's storm on all aspects from 1900-2800 m. South and west aspects were the most reactive with slabs running on the recently buried late-March crust. In the days following the storm, several size 2 skier and remotely (from a distance) triggered storm slab avalanches were reported. Activity on Thursday was mostly on east aspects at treeline. Skier triggered slabs were mostly 30-50 cm thick and ran on the late-March layer.

Snowpack Summary

Another 20-30 cm of new snow on Friday brought the weekly total throughout the region to 40-80 cm. Strong west winds have redistributed the snow in alpine and treeline terrain.The storm snow sits on a layer buried in late-March that consist of crusts below 1900 m and on south aspects, and surface hoar on shaded aspects at higher elevations.A deeper layer buried mid-March is now 60 to 90 cm below the surface, and is similar to the late-March interface.Deeper persistent weak layers from January and December are still being reported by professional observers, but are generally considered dormant.

Avalanche Problems

Storm Slabs

Human-triggered storm slabs remain a concern on wind-affected features and on south aspects where they sit above buried sun crusts. Periods of sunshine may also undermine stability on any sun-exposed slopes.

Minimize exposure to steep planar south-facing slopes - especially if they see sunshine.Choose well supported terrain without convexities.Be careful with wind loaded and cross-loaded slopes, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1.5 - 3