Avalanche Forecast

Issued: Mar 11th, 2020 2:00AM

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

Jesse Percival, VIAC

Vancouver Island.

On Sunday numerous loose dry avalanches were reported as skier triggered on steep west aspects no larger than size one. Tuesday a skier accidental was reported on a north aspect at 1400 m. The party trigger a size 2 avalanche on a convex roll feature. New snow that had buried surface hoar was then warmed slightly with slab properties becoming present. There was involvement in the avalanche but no injuries or lost gear was reported.

Summary

Past Weather

Spring is nearing so its time to pay attention to the rapid effects the sun has on the snow pack. Even a brief period of sun will cause the upper snow pack to become unconsolidated, promoting small avalanches to gain mass and become destructive. The other effect of sun and warming is the rapid settlement of new snow, this can cause new snow to form slabs in a very short time. Clear sky allowed of the development of surface hoar followed by light snowfall that then buried it.

Weather Forecast

A pacific storm system will deliver on Friday to the forecast area, moderate to strong south east wind and moderate snowfall. Prior to this mostly clear conditions with some convective activity will bring isolated snow flurries.Wednesday: 0-5 cm of new snow, Winds Moderate from the North West, Freezing levels to 1000 meters.Thursday: 0-5 cm of new snow, Winds Moderate from the West, Freezing levels to 900 meters.Friday: 20-30 cm of new snow, Winds becoming strong from the South East, Freezing levels 500 meters.

Terrain Advice

Careful and cautious route finding when entering into or over convex rolls or steep features.Test small safe features to determine the bond of new snow on the surface hoar before venturing into anything that requires commitment. Avoid traveling both above and below cornice features.If storm snow amounts exceed 30 centimeters, expect hazard rating to rise to high.

Snowpack Summary

New snow has buried a surface hoar layer that formed during a brief period of cool and clear conditions. On solar aspects the period of warming unconsolidated snow in the upper snow pack began to refreeze overnight forming a crust on steep solar aspects. The mid and lower snow pack is continuing to settle increasing in strength and density.

Snowpack Details

Surface: New snow overlies surface hoar .
Upper: A supportive and strengthening bond between the past melt freeze crust down from 15 to 30 cm.
Mid: A variety of old crusts can be found.
Lower: Well settled and dense.

Confidence

Moderate - A variety of quality field data and reports with weather models disagreeing on snowfall amounts.

Problems

Wind Slabs

Found on predominantly North aspects, this avalanche problem is likely to become a deeper and bigger problem as new snowfall and wind transport continue to load a buried surface hoar interface. **Location:** Specific to North aspects and found in both the Alpine and at Treeline. **Possibility:** Triggering of this avalanche problem is possible to likely from light loads such as skiers. Natural avalanches are possible. **Size:** If triggered expect these avalanches to be small, and on isolated terrain features large, size 2.

Likelihood

Possible

Expected Size

1 - 1

Storm Slabs

This new avalanche problem will come into play on Thursday night into Friday as new snow begins to bury surface hoar and old hard surfaces. **Location:** Specific to areas protected from the wind and found at all elevations. **Possibility:** Triggering of this avalanche problem is likely to very likely from light loads such as skiers. Natural avalanches are possible to likely. **Size:** If triggered expect these avalanches to be large size 2, and on isolated terrain features very large, size 3.

Likelihood

Possible

Expected Size

1 - 1

Valid until: Mar 12th, 2020 2:00AM