Archived

Avalanche Forecast

Mar 25th, 2019–Mar 26th, 2019

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

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

Small loose wet avalanches may gather mass, become much larger, and run farther into low angle terrain than expected.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY NIGHT: Clear / Light, northeasterly winds / Alpine low -1 C / Freezing level 1000 m.TUESDAY: Mix of sun and cloud / Light, northwesterly winds / Alpine high -1 C / Freezing level 1500 m.WEDNESDAY: Sunny / Light, easterly winds / Alpine high 0 C / Freezing level 1500 m.THURSDAY: Sunny / Light, southerly winds / Alpine high 0 C / Freezing level 1500 m.

Avalanche Summary

Natural avalanche activity has tapered off, but concern remains for human triggering loose wet avalanches during the heat of the day and persistent slab avalanches in north facing alpine terrain.

Snowpack Summary

At upper elevations, 30-50 cm of well settled snow overlies weak facets (sugary snow) that were around March. 10th. which is currently the primary layer of concern for human triggering persistent slab avalanches.Lower down in the snowpack, the base is composed of weak facets. Large avalanches initiating on these facets are most likely in rocky, alpine terrain where there is a shallow or highly variable snowpack depth. They would likely require a large trigger such as a cornice fall, snowmobile, or a group of people standing in the same spot.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.

Avalanche Problems

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.

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

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

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

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

Aspects: North, North East, North West.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 2.5