Archived

Avalanche Forecast

Mar 23rd, 2018–Mar 24th, 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

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

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: Lizard-Flathead.

Strong winds are driving the alpine danger to CONSIDERABLE. Watch for whumphing and cracking below your feet and continue to make observations while gaining elevation towards alpine terrain.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Saturday: Mainly cloudy. New snow 5-10 cm accompanied by strong southwest ridgetop winds. Alpine temperatures near -2 and freezing levels 1200 m.Sunday: Mix of sun and clouds. Ridgetop wind strong from the West and freezing levels near 1400 m.Monday: Cloudy with some sunny periods and isolated flurries. Ridgetop wind generally light with strong gusts from the southwest. Alpine temperatures near -4 and freezing levels 1400 m.

Avalanche Summary

On Friday, numerous natural storm slab avalanches were reported from North aspects above 1700 m. I suspect with the strong winds and new on Saturday this problem may persist.

Snowpack Summary

Up to 20 cm of new snow will initially have a poor bond to the plethora of old snow surfaces including a melt-freeze crust on sunny aspects, surface hoar on north aspects above 1600 m and moist snow surfaces below 1600 m. Wind slabs are building on most aspects due to the changing winds and overhanging cornices exist along ridgelines. Deeper in the snowpack, the mid-December and late-November weak layers are composed of crusts and sugary facets, which are down 150-300 cm. These layers are currently dormant.

Avalanche Problems

Wind Slabs

Changing winds from East-West continue to be strong, redistributing the recent storm snow onto most aspects. Wind slabs will likely be reactive to skier/rider triggers and loose dry avalanches may occur from steeper terrain features.

Use ridges or ribs to avoid pockets of wind loaded snow.Avoid large slopes and convex features.Wind slabs may be more reactive where they sit on a buried crust or surface hoar interface

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Cornices

Large looming cornices exist across ridgelines. Cornices are unpredictable and demand respect. They're more likely to fail during wind events or if the sun comes out.

Give cornices a wide berth when travelling on or below ridges.Pay attention to overhead hazards like cornices which could trigger a slab from the slope below.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2.5