Northwest Coastal Avalanche Forecast

Issued: Mar 14th, 2021 4:00PM

Mon Mar 15th Current Conditions
Alpine Considerable Treeline Considerable Below Treeline Moderate
Tue Mar 16th 2 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Moderate
Wed Mar 17th 3 Day Outlook
Alpine Considerable Treeline Moderate Below Treeline Moderate

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Persistent Slabs.

The snowpack will need time to stabilize after the recent intense storm. Storm and wind slabs will be reactive to skiers and riders. Be cautious and watch for signs of instability like whumpfing, hollow sounds, shooting cracks and recent avalanche activity.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

SUNDAY NIGHT: Clear, 30 km/h northwest wind, alpine low -17 C. 

MONDAY: Cloudy, up to 5 cm new snow, 30 km/h southwest wind, alpine high -5 C.

TUESDAY: Cloudy, 10 to 15 cm new snow, 60 km/h southerly wind, alpine high 1 C, freezing level rising to 1000 m.

WEDNESDAY: Mix of sun and cloud, 10 to 15 cm new snow, 60 km/h south wind, alpine high 1 C, freezing level at 1000 m.

Avalanche Summary

A widespread natural avalanche cycle with storm slab avalanches up to size 4 started on Friday morning and continued into Saturday. Explosives triggered storm slab avalanches of size 2 to 3 in the entire region. A natural persistent slab avalanche of size 3.5 was observed east of Kitimat. Numerous wet slab avalanches up to size 3 and wet loose avalanches of size 1 to 2 were observed as well as several glide snow avalanches up to size 2.5.

Several natural glide snow avalanches and loose wet avalanches up to size 2 were reported on Wednesday. Some avalanche activity was observed on southerly aspects on Tuesday during the heat of the day. A few cornices were also triggered, which did not trigger slabs on the slopes below.

Snowpack Summary

The recent storm brought up to 150 cm snow in the south of the region and about 50 cm in the north. The precipitation was combined with moderate to strong southerly wind and fell as rain below 900 m saturating the upper snowpack. The new snow may overly feathery surface hoar on northerly aspects and in sheltered terrain features around treeline or a melt-freeze crust on southerly aspects and below treeline.

Around 100 to 300 cm overlies a persistent weak layer buried in mid-February that may still be a concern in parts of the region. The layer consists of feathery surface hoar crystals in areas sheltered from the wind and sugary faceted grains that formed during February's cold snap. Avalanche activity on this layer has mostly occurred west of Terrace along Highway 16 and in the Kitimat area in the past week, but the layer could still be of concern anywhere it exists.

There are currently no layers of concern in the mid and lower snowpack.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Storm Slabs

An icon showing Storm Slabs

Likelihood

Likely-Very Likely

Expected Size

1.5 - 3

The recent storm brought up to 150 cm snow in the southern half of the region and about 50 cm in the north. The storm snow will stay reactive while it settles, especially where it sits on surface hoar on northerly aspects and in sheltered terrain features around treeline or a melt-freeze crust on southerly aspects. The precipitation fell as rain below 900 m and saturated the upper snowpack.

Moderate to strong southerly wind has formed wind slabs during the storm which will be reactive to skiers and riders. The wind contributed to cornice growth and the additional load might lead to cornice failures.

Aspects:

All aspects.

Elevations:

All elevations.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5

Around 100 to 300 cm of snow may overly a persistent weak layer buried in mid-February. The likelihood of triggering the layer might stay elevated while the recent storm snow settles.

Failing cornices may trigger avalanches on this layer on the slopes below and create very large avalanches.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Mar 15th, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.