Avalanche Forecast

Issued: Nov 24th, 2017 4:45PM

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

jmcbride, Avalanche Canada

Sea To Sky.

With more snow in the forecast, expect storm slabs.

Summary

Confidence

Weather Forecast

The next wave of warm and wet weather is expected to arrive by Saturday morning with freezing levels forecasted to rise to 2500m on Sunday.Saturday: Snow, accumulation 20-30 cm. Moderate to strong south wind. Alpine temperature -1. Freezing level 1500 m.Sunday: Heavy snow and rain below 2000 m, accumulation 30-40 cm. Strong south wind. Alpine temperature 2, Freezing level 2500 m.Monday: Flurries, accumulation 5-10 cm. Moderate southwest wind. Alpine temperature -5. Freezing level 1000 m.

Avalanche Summary

Wednesday's rain to mountain tops produced numerous, small to very large natural, loose, wet avalanches as rain drenched all elevations. In some areas these avalanches were associated with debris flows and several washouts along FSR roads and trails have been reported. Avalanche activity has since subsided with a return to cooler temperatures and lower freezing levels but will increase again as the new snow and wind build storm slabs at alpine and treeline elevations.

Snowpack Summary

Approximatley 20-30 cm of new snow overlies the November 23 crust This 5-10 cm thick crust can be found on all aspects above 1400 m and overlies a saturated upper pack. Below treeline the snowpack consists of wet snow from top to bottom. In high alpine and glaciated terrain the November 9th layer of weak sugary crystals above a crust near the base of the snowpack is now buried 150 - 240 cm deep.

Problems

Storm Slabs

Storm slabs will be most reactive above 1400m where the new snow overlies the recent crust.

Use extra caution in lee areas where recent snow and wind loading have created storm slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Wet

The possibility of triggering a loose, wet slide may still be possible in steep or unsupported terrain. Even a small, wet slide can gain enough mass to become a big problem.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Nov 25th, 2017 2:00PM