Avalanche Forecast

Issued: Feb 5th, 2023 4:00PM

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

ahanna, Avalanche Canada

Sea To Sky, Brandywine, Garibaldi, Homathko, Powell River, Spearhead, Stave, Tantalus.

Avalanche conditions will deteriorate in the afternoon as new snow and strong winds increase storm slab size and sensitivity to triggering.

There is some uncertainty around the timing of the incoming storm and how much snow will pile up by the end of the day, so be alert to changing conditions and have a safe egress route planned.

Summary

Confidence

Moderate

Avalanche Summary

Storm slabs have been reactive in recent days. On Friday and Saturday, we had reports of skier-triggered size 1s, naturals up to size 1.5, and explosive-triggered up to size 2. On Thursday, reports of small slabs being triggered remotely show evidence of a poor bond with underlying surfaces.

If you head to the backcountry please post your reports and photos to the Mountain Information Network, the information is very helpful to forecasters.

Snowpack Summary

The next storm is expected to bring 5-15 cm by the end of the day Monday, bringing recent totals to 20-40 cm sitting over old wind affected surfaces and hard crusts. Strong southwest winds are transporting this new and recent snow into deep pockets of wind slab on north and east facing terrain at upper elevations. At lower elevations, recent precipitation may have fallen as rain.

A crust from mid-January can be found down 40 to 70 cm deep. A number of weak layers exist within the middle and lower snowpack, but the thick crusts sitting above them make triggering avalanches on these layers unlikely. The areas of concern in terms of triggering a deeper layer are shallow rocky areas where the snowpack varies from thick to thin.

Weather Summary

Sunday night

Cloudy. A trace of snow possible. Light southwest wind. Freezing level dropping to 800 m.

Monday

5-15 cm of new snow. Strong southwest winds. Freezing level around 1400 m. Snow line around 1200 m.

Tuesday

10-30 cm new snow overnight, another 5-15 cm during the day. Strong southwest winds. Freezing levels dropping 1400 to 1000 m. Snow line 1200 m dropping to valley bottom.

Wednesday

5-10 cm overnight then clearing to a mix of sun and cloud. Light southwest wind. Freezing level 800 m.

Wednesday

Cloudy with isolated flurries, 10-15 cm accumulation. Southwesterly ridgetop winds 40 to 60 km/h. Treeline temperatures warm to -1 ËšC. Freezing levels 1300 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Storm slab size and sensitivity to triggering will likely increase through the day.
As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.
Be especially cautious as you transition into wind affected terrain.
Dial back your terrain choices if you are seeing more than 20 cm of new snow.

Problems

Storm Slabs

Snow continues to accumulate over a variety of surfaces including stiff wind slabs and a faceting crust, which may take time to bond.

Strong southwesterly winds are transporting storm snow into deep pockets in lees.

At lower elevations precipitation may fall as wet snow or rain, watch for loose wet avalanche potential on steep slopes as the surface snow loses cohesion.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 6th, 2023 4:00PM