Avalanche Forecast

Issued: Apr 17th, 2022 4:00PM

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

wlewis, Avalanche Canada

Sea To Sky.

Winter continues with another round of new snow - watch for reactive storm slabs building at all elevations.

Stick to conservative terrain as snowfall accumulates and minimize your exposure during heavy snow or wind.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

SUNDAY NIGHT: Mostly cloudy. Moderate to strong south/south easterly winds. Freezing levels remain around 1300 m for the night, but fall to 1000 m by morning.

MONDAY: Snow begins early morning with 10-20 cm expected. Freezing levels reach 1200 m. Strong southeast winds ease over the day. A further 10-25 cm is possible overnight.

TUESDAY: Cloudy up to 5 cm of snow over the day. Freezing levels reach 1000 m. Moderate westerly winds.

WEDNESDAY: Clearing skies with no snowfall expected. Moderate southeast winds. Freezing levels rise to 1300 m.

Avalanche Summary

On Saturday, small pockets of wind slab were still reactive to skier triggers on west facing slopes. Several wet avalanches were reported on south facing slopes during afternoon sun.

Several cornice falls have been observed over the last week, affected by brief periods of strong sunshine. On Thursday, a cornice fall produced a size 3 slab avalanche on a northeast slope. This avalanche failed on a deep weak layer within the snowpack, which is considered unlikely to occur from human or natural triggers at this time - except for large cornice falls.

Snowpack Summary

Up to 20 cm of storm snow is expected by Monday afternoon. This will likely form reactive storm slabs at all elevations above the freezing level. Deeper deposits are expected in west and north facing terrain features at higher elevations, as strong south-southeast winds are forecast.

Several thin crusts exist on south facing slopes from recent sunshine, and a widespread and supportive crust is now buried 30-80 cm deep. Reports suggest these crusts are currently bonding well with the layers around it.

The mid and lower snowpack is considered strong at this time, consisting of hard snow and melt freeze crusts.

Terrain and Travel

Watch for fresh storm slabs building throughout the day.
Storm slab size and sensitivity to triggering will likely increase through the day.
Be careful as you transition into wind affected terrain.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Storm Slabs

Storm slabs will build over the day as snowfall totals increase. Expect reactivity as storm snow falls on a variety of surfaces including a crust on south facing slopes. Lower elevations may see rain or mixed precipitation.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornices may be weak and reactive to human triggers. They are a significant hazard alone, and may produce large slab avalanches as they fall onto the slope below. Cornice falls are more likely as temperatures warm each day, or when strong sunshine is present.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Apr 18th, 2022 4:00PM