Avalanche Forecast

Issued: Nov 25th, 2018 4:04PM

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

cgarritty, Avalanche Canada

Sea To Sky.

Dial back your terrain selection during the storm. Storm slabs will form rapidly where precipitation falls as snow rather than rain.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Sunday night: Wet flurries bringing 10-15 cm of new snow mainly to alpine elevations. Moderate to strong south winds.Monday: Mainly heavy rain with possible accumulations of up to 40 cm of new snow above 1800 metres. Strong to extreme south winds. Alpine high temperatures around 0 with freezing levels to 2200 metres or higher.Tuesday: Heavy rain transitioning to snowfall over the day with possible accumulations of up to 25 cm of new snow, primarily in the alpine. Moderate southwest winds. Alpine high temperatures of 0 to -1 with freezing levels declining from around 2100 to 1800 metres over the day.Wednesday: Cloudy with flurries bringing about 10 cm of new snow. Light southwest winds. Alpine high temperatures around -3 with freezing levels around 1400 metres.

Avalanche Summary

Small natural and skier-triggered storm slab avalanches were observed out of steep, wind-loaded terrain at alpine elevations in the Whistler area on Friday and Saturday. The incoming storm is expected to build another round fresh storm slabs above the rain line on Monday.Please submit any observations you have to the Mountain Information Network here,

Snowpack Summary

The deepest snow is found at alpine elevations, with depths of around 60-100 cm. Approximately 30 cm of newer snow now lies above older wind slabs that formed with strong southerly winds on Wednesday. Below this lies a thin crust, now buried around 50 cm. A thicker lower crust, that may be associated with weak faceted crystals in some places lies close to the ground. This is most likely to cause problems in glaciated terrain or on smoother, high elevation slopes where the summer snow did not melt out.

Problems

Storm Slabs

Touchy storm slabs are expected to form rapidly at high elevations that see heavy snowfall instead of heavy rain. Strong winds will speed slab formation in the lee of wind-exposed terrain features.

Cornices are already large and looming near ridges. Give them a wide berth.Be especially careful around wind loaded pockets near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Very Likely - Certain

Expected Size

1 - 2

Loose Wet

Heavy rain is set to saturate the snowpack at lower elevations and promote active loose wet avalanche conditions on Monday.

Use extra caution around steeper slopes if the snow is moist or wet.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Very Likely - Certain

Expected Size

1 - 1.5

Valid until: Nov 26th, 2018 2:00PM