Avalanche Forecast

Issued: Mar 18th, 2017 4:05PM

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

shorton, Avalanche Canada

Sea To Sky.

A cooling trend will eventually help stabilize the snowpack. Continually reassess conditions as you travel into avalanche terrain and be aware of the potential for deeper weaknesses in the snowpack.

Summary

Confidence

High - The weather pattern is stable

Weather Forecast

SUNDAY: Clearing skies following the storm with isolated flurries, light northwest winds, alpine temperatures around -10 C.MONDAY: Cloudy with sunny periods, light southeast winds, alpine temperatures around -5 C.TUESDAY: Flurries with 5-10 cm, moderate southwest winds, alpine temperatures around -3 C.

Avalanche Summary

On Saturday, explosive control and ski cutting produced numerous small storm slabs (size 1-1.5) and two size 2 storm slabs up to 50 cm deep. Most failed within the storm snow, but a few on the mid-March rain crust.On Sunday, storm slabs may remain reactive in human triggers and the deeper mid-February weak layer continues to present a low probability / high consequence scenario.

Snowpack Summary

Roughly 30 cm of storm snow now sits above a widespread rain crust up to 2200 m. Thicker wind slabs and large cornices likely exist in alpine terrain. Reports suggest the storm snow is generally well bonded to the crust, and cooling temperatures should help stabilize the upper snowpack. The mid-February crust/facet layer is now 80-120 cm deep and may be up to 200 cm deep in wind loaded terrain. This layer was reactive prior to recent warming events, but now there's some uncertainty as to how long it will remain reactive.

Problems

Storm Slabs

Storm slabs may remain reactive at higher elevations and in wind-affected terrain.

Avoid freshly wind loaded features.Test slopes before committing to them.New snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Heavy triggers such as a cornice fall or a small avalanche could potentially step down to a weak layer buried about 1 m deep.

Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 19th, 2017 2:00PM