Sea to Sky Avalanche Forecast

Issued: Mar 21st, 2021 4:00PM

Mon Mar 22nd Current Conditions
Alpine Considerable Treeline Moderate Below Treeline Moderate
Tue Mar 23rd 2 Day Outlook
Alpine Moderate Treeline Moderate Below Treeline Low
Wed Mar 24th 3 Day Outlook
Alpine Moderate Treeline Moderate Below Treeline Low

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

New snow will need some time to stabilize on Monday, don't let it lure you into consequential avalanche terrain.

Summary

Confidence

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

Weather Forecast

A cool northwest flow starts in the wake of the Sunday night storm.

SUNDAY NIGHT: The trailing end of the storm delivers up to 15 cm around Whistler and up to 30 cm further south and west, 40-60 km/h southwest wind, treeline temperatures drop to -8 C.

MONDAY: Mix of sun and cloud, winds ease and shift to the northwest in the morning with some moderate gusts, freezing level climbing to 1200 m with treeline temperatures around -5 C.

TUESDAY: Mix of sun and cloudy, light southwest wind, treeline temperatures around -6 C.

WEDNESDAY: Cloudy with scattered flurries bringing 5-10 cm of snow, 30-50 km/h southwest wind, freezing level climbing to 1400 m with treeline temperatures around -3 C.

Avalanche Summary

Storm slabs were actively growing throughout the day on Sunday and will continue to grow overnight. While we do not yet have any field reports at the time of publishing, it is likely some of these slabs were becoming reactive later in the day. Some natural avalanche activity is possible overnight, but then as the weather clears on Monday the main concern will be human triggered slabs in the top 20-40 cm of snow.

On Saturday there were a few reports of small size 1 storm slab avalanches from the previous storm as well as some large explosive triggered cornice falls.

Snowpack Summary

Sunday's storm will deliver 15 cm of fresh snow around Whistler and up to 40 cm further west and south. Strong southwest wind will form extra deep deposits at upper elevations. This will bring recent storm totals to 40-80 cm, which sits above a widespread melt-freeze crust (except on high elevation northerly aspects). Recent observations suggest the snow has bonded well to these old interfaces. The lower snowpack is well bonded, although a spotty early season facet layer deep in the snowpack could return as a problem later in the season.

Remember that cornices along ridgelines are large at this time of year and always have the possibility of failing naturally or from the weight of a human.

Terrain and Travel

  • Use careful route-finding and stick to moderate slope angles with low consequences.
  • Avoid freshly wind loaded terrain features.
  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • 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

Expected Size

1 - 2.5

Storm slabs will likely be reactive to human triggering on steep and wind loaded slopes. Give the snow time to strengthen before pushing into consequential avalanche terrain.

Aspects:

All aspects.

Elevations:

All elevations.

Cornices

An icon showing Cornices

Likelihood

Possible

Expected Size

2 - 3

Cornices are large and looming along many ridgelines, and have likely grown with the recent snow and wind.

Aspects:

North, North East, East, West, North West.

Elevations:

Alpine.

Valid until: Mar 22nd, 2021 4:00PM

Forecast Trend

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