Avalanche Forecast

Issued: Dec 30th, 2016 4:45PM

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

Avalanche Canada rbuhler, Avalanche Canada

Watch for signs that the recent storm snow is still reactive to triggering. Slabs will be most reactive in wind loaded terrain features.

Summary

Confidence

Low - Due to the number of field observations on Friday

Weather Forecast

Light snowfall is expected for most of Saturday with models typically showing around 5 cm of accumulation. However, one model is showing the potential for up to 15 cm of new snow along the coast. Alpine wind is forecast to be moderate to strong from the northwest and freezing levels are expected to be around 300 m. A mix of sun and cloud is forecast for Sunday with moderate northeast winds and freezing levels falling to sea level. Sunny conditions are currently forecast for Monday with moderate outflow winds continuing and treeline temperatures falling close to -15C.

Avalanche Summary

On Thursday during the storm, the storm snow was reported to be touchy and ski cutting in the early afternoon was produced storm slabs size 1-2 in the North Shore mountains with crowns 30-50 cm thick. Isolated natural activity was observed from steep wind loaded terrain during afternoon in the same area. On Saturday, storm slabs remain an isolated concern but wind loaded areas are expected to be the main area of concern. Strong alpine winds were from the south at the start of the storm on Thursday and were from the west by the end of the storm. Winds on Saturday are now coming from the north. As a result, wind slabs should be expected on all aspects in wind affected terrain.

Snowpack Summary

Up to 50 cm of new snow accumulated from Thursday's storm. This brings the total storm snow amounts since Monday to around 100 cm in the North Shore mountains. Reports on Thursday suggest the storm snow from the beginning of the week is well bonded and stable, and the new avalanche activity has been isolated to snow that fell on Thursday. This new snow is expected quickly gain strength and stabilize going into the weekend. Recent strong winds have been from a variety of directions and have been loading leeward and cross loaded features in wind exposed terrain.  A crust that formed a week ago is likely down over 1 m. Below this crust, the snowpack is generally considered well settled and stable.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm slabs from Thursday may still be reactive to human triggering on Saturday, especially in wind loaded terrain and on steep slopes. Winds have recently changed direction and slabs should be expected on all aspects in wind exposed terrain.
Avoid freshly wind loaded features.Give the new snow time to settle and stabilize before pushing into big terrain.Recent winds have changed direction. Watch for wind slabs on all aspects.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 31st, 2016 2:00PM