Avalanche Bulletin - Sea to Sky

Date Issued:

Valid Until:

Forecaster:ahanna

As the weather clears in the afternoon, give the fresh storm slab time to settle. We expect it to be most reactive in wind loaded lees at upper elevations, and on south aspects where the new snow may sit on a thin melt-freeze crust.

Mon, 30 NovTue, 01 DecWed, 02 Dec
Alpine3 Considerable3 Considerable2 Moderate
Treeline3 Considerable2 Moderate2 Moderate
Below Treeline1 Low1 Low1 Low
Confidence: Moderate

Travel and Terrain Advice

Storm Slab

New snow and wind are building fresh storm slabs throughout the morning. A touch of sun in the afternoon may keep them extra sensitive. Be especially cautious where wind deposits fat pockets of snow in lee features, and on south aspects where the new snow may sit on a thin melt-freeze crust. 

Forecast Details

Avalanche Summary

Monday we're expecting storm snow avalanches size 1-2 especially in lee features where wind deposits fatter pockets of snow, or on wind-sheltered south aspects where the new snow may be falling on a thin melt-freeze crust.

Our eyes and ears in the mountains are limited at this time of year and may continue this winter due to fewer professional observations. If you see anything (or don't) while out in the field, please consider sharing via the Mountain Information Network (MIN). Photos are especially helpful! Thank you so much for all the great MINs submitted so far!

Snowpack Summary

15-25 cm of new snow falls ontop of wind affected surfaces at upper elevations and a thin melt-freeze crust on south aspects. Moderate to strong southwest winds will likely form fat pockets of reactive storm slab in lee terrain features.

The snowpack depth varies substantially with elevation. Below treeline 30 to 70 cm, 80 to 100 cm near treeline, and around 150 cm may be found in the alpine.

The mid to lower snowpack contains a series of crusts, the most notable of which is also the deepest, sitting 30 cm above the ground at elevations above 1500 m. This crust may have a thin overlying layer of weak faceted grains and/or surface hoar crystals, especially in sheltered areas around treeline. There is uncertainty as to whether these layer will be a concern going forward. 

Weather Forecast

Sunday night: 10-15 cm new snow, strong southerly wind, freezing level 1000 to 1200 m.

Monday: 5-10 cm new snow then clearing in the afternoon. Moderate northwest wind easing to light, freezing level 1000 m.

Tuesday: Clear, light northwest wind, freezing level spiking to 3200 m.

Wednesday: Clear, light southeast wind, freezing level 3200 m.