Avalanche Forecast

Issued: Apr 18th, 2017 4:56PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Cornices and Loose Wet.

mgrist, Avalanche Canada

South Coast Inland.

Wind slabs and cornices are the main concerns right now. Carefully assess terrain before committing to bigger lines.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

We're looking at unsettled and variably wet spring weather through Thursday, with clearing and fine weather for Friday.WEDNESDAY: More wet snow (5-10cm) above 1600m and the potential for intense squalls (and thunderstorms). Winds moderate southerly.THURSDAY: Isolated flurries (5-10cm possible) with wet snow above 1500m. Winds light southwesterly.FRIDAY: Sunny with cloudy periods. Freezing level rising to 2100m. High temperatures to +4 Celsius. Winds light southerly. NOTE: The convective flurries which are common during this time of year can result in widely varying snowfall amounts throughout a region. These spring squalls routinely drop 20+ cm of snow in one valley while the adjacent drainage remains dry. For this reason, the distribution of avalanche problems associated with new snow, such as wind slabs, can vary greatly within a region.

Avalanche Summary

No new observed; however, deep persistent weak layers (including the November facet/crust combination) remain possible to trigger with large loads such as cornices. Loose wet avalanches are also possible below treeline where the temperatures have remained above freezing.

Snowpack Summary

This region received 7-10cm of snow above 1500m on Monday into Tuesday. It fell on light amounts of previous snow (10-20 cm over the long weekend) which settled into isolated stiff wind slabs in the immediate lee of exposed terrain features at treeline and above.Dry snow can still be found on north aspects above 1900m; however, moist (or crusty) snow can be found under the most recent snow on almost all south-facing slopes at all elevations.Cornices remain large in some areas and could trigger large avalanches when they fail (especially when warmed by the sun). The fatal accident near Lions Bay a week ago illustrates the danger of cornices breaking off, and the large avalanches they can trigger.

Problems

Wind Slabs

Shifting wind directions have created wind slabs on a variety of aspects, primarily in the alpine.

Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.Avoid travelling in areas that have been reverse loaded by winds.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Recent snow and wind have created large cornices. Minimize your exposure to cornices when it is cold and cloudy and completely avoid them when it is warm and/or sunny.

Give cornices a wide berth when travelling on or below ridges.Falling cornices can trigger large avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

Loose wet avalanches are more likely at lower elevations where the snowpack may be isothermal and precipitation falls as rain. Even small slides can have serious consequences.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

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