Archived

Avalanche Forecast

Apr 22nd, 2018–Apr 23rd, 2018

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

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

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: Northwest Coastal.

Avalanche danger will increase as the temperatures rise throughout the week.

Confidence

Low - Due to the number of field observations

Weather Forecast

MONDAY: Mostly cloudy. Strong southwest wind. Alpine temperature +5. Freezing level 1600 m.TUESDAY: Mix of sun and cloud. Moderate west wind. Alpine temperature +3. Freezing level 1400 m. WEDNESDAY: Sunny. Light west wind. Alpine temperature +10. Freezing level 3000 m.

Avalanche Summary

Several very large deep persistent slab avalanches(size 3-4) which were triggered by cornice failures and several natural wind slabs up to size 2.5 were reported near Bear Pass on Saturday. Avalanche reports have been limited due to very few information sources this time of year. If you have been out, please post your observations on the Mountain Information Network. (MIN)

Snowpack Summary

Cornices are large and when they fail there is the potential to trigger large avalanches on deeply buried weak layers. Lingering wind slabs may still be reactive to human triggers on leeward slopes below ridgetops.In the south of the region, two layers of surface hoar are buried early-March and mid-March are approximately 70-100 cm deep and most prominent on north to east aspects. Further north, these layers are around 40 cm deep.Below these March layers the mid-pack is generally well-settled and strong. However in the far north of the region there are weak sugary facets near the bottom of the snowpack.

Avalanche Problems

Wind Slabs

Lingering wind slabs may still be reactive to human triggers in wind affected terrain at treeline and above.

Travel on ridgetops to avoid wind loaded slopes.Avoid areas that look freshly loaded with snow; especially convex features below ridgetops.Use caution when transitioning into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Loose Wet

When the sun comes out it will quickly weaken the surface snow and cause loose wet avalanching on steep solar slopes.

Watch for signs that the snow is heating up such as pin-wheeling or the surface snow becoming moist.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2

Cornices

Sunshine and warming temperatures will increase the likelihood of cornice fall.

Cornices become weak with daytime heating. Give them a wide berth both from above and below.Falling cornices may trigger persistent weak layers deeper in the snowpack.

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

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3.5