Avalanche Forecast

Issued: Mar 24th, 2019 4:11PM

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

jsmith, Avalanche Canada

Northwest Coastal.

Avoid steep, rocky terrain in the alpine where there is a shallow or highly variable snowpack depth. This will reduce the likelihood of triggering large persistent slab avalanches.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

SUNDAY NIGHT: Clearing / Light, northeasterly winds / Alpine low -2 C / Freezing level 1500 m.MONDAY: Sunny / Light, northeasterly winds / Alpine high 2 C / Freezing level 1500 m.TUESDAY: Sunny with cloudy periods / Light, southwesterly winds / Alpine high 2 C / Freezing level 1500 m.WEDNESDAY: Mix of sun and cloud / Moderate, southeasterly winds / Alpine high 2 C / Freezing level 1600 m.

Avalanche Summary

Natural avalanche activity has tapered off but concern remains for human triggering persistent slab avalanches on a layer of facets that are down 50-100 cm. Explosive control work on Thursday produced several large avalanches, up to size 3, on this layer.

Snowpack Summary

At upper elevations, 50-100 cm of well settled snow overlies weak facets (sugary snow) that were buried around March. 10th. which is currently the primary layer of concern for human triggering persistent slab avalanches.Not much further below the March 10th interface is a second weak layer of facets buried on February 19th. Recent loose wet and slab avalanches have been observed gouging into this faceted snow and entraining additional mass.The prolonged warm spell has transitioned sun exposed slopes in the alpine and all aspects at treeline and below towards becoming isothermal (0 C throughout the snowpack). In these areas that have entered spring conditions, the avalanche hazard will fluctuate greatly depending on the strength of the overnight freeze and how quickly the snowpack is warmed up each day. Check out this guide to managing avalanche hazard during spring conditions HERE.

Problems

Persistent Slabs

Human triggering of large persistent slab avalanches is most likely in rocky, alpine terrain with a shallow or highly variable snowpack depth.

Avoid steep, rocky terrain in the alpine where there is a shallow or highly variable snowpack depth.Use extra caution around moraines that tend to have highly variable snowpacks.Avoid re-grouping in rocky areas with a shallow snowpack, remote triggering is still possible.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 2.5

Loose Wet

This problem is more likely at lower elevations where there was a weak or no overnight re-freeze. Sunshine and air temperatures above 0 C can rapidly increase the likelihood of triggering loose wet avalanches.

Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.Avoid sun exposed slopes when the solar radiation is strong, especially if the snow is moist or wet.Cornices become weak with daytime heating, travel early on exposed slopes.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 25th, 2019 2:00PM