Avalanche Forecast

Issued: Mar 22nd, 2017 3:55PM

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

Avalanche Canada shorton, Avalanche Canada

A persistent slab above a crust may take time to stabilize. Evaluate the terrain and snowpack carefully before committing to steeper terrain.

Summary

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

THURSDAY: Unsettled weather with flurries bringing 5-15 cm of snow, moderate and gusty south wind, alpine temperature around -7 C.FRIDAY: Isolated flurries, moderate south wind, alpine temperature around -4 C.SATURDAY: Scattered flurries with 5-10 cm, moderate southwest wind, alpine temperature around -4 C.

Avalanche Summary

On Tuesday, a skier near Hazelton remotely triggered a size 1 avalanche that subsequently triggered two other size 2 avalanches on a persistent weak layer (30 cm deep). The avalanches occurred on northeast aspects at 1400 m. On Monday, a size 3 slab avalanche was triggered by a cornice fall on a north aspect at 1700 m north of Kispiox. Over the weekend, several reports describe reactive slabs above a crust, including a size 2.5 snowmobile-triggered avalanche in the Telkwas and a size 2 skier-triggered wind slab north of Kispiox.Steady loading and warming should keep the persistent slab reactive throughout the week.

Snowpack Summary

Unsettled weather with moderate winds is redistributing snow in exposed terrain. Mild temperatures have promoted the settlement of recent snow into a 20-60 cm thick slab above a crust interface. Recent reports suggest the bond to the crust is poor and has formed a reactive slab. Weak sugary snow near the ground has been a dormant instability, but it may still be possible to trigger in steep rocky terrain.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A 20-60 cm thick slab above a rain crust has been reactive to human triggers over the past week. Most activity has been in wind-affected terrain. Persistent slabs also have the potential to step down to deep basal weaknesses near the ground.
Choose well supported terrain without convexities.Avoid steep convexities or areas with a thin or variable snowpack.If triggered the persistent slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 23rd, 2017 2:00PM