Avalanche Forecast

Issued: Apr 10th, 2019 3:59PM

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

dsaly, Avalanche Canada

Sea To Sky.

Wet flurries and warm temperatures can quickly warm the snowpack and increase the likelihood for loose wet avalanches. As you gain elevation and find dry snow, be wary of slabs around ridge crests and in lee terrain.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

WEDNESDAY NIGHT: Cloudy with isolated flurries / southwest wind, 10-20 km/h / alpine low temperature -5 C / freezing level 1000 mTHURSDAY: Flurries, trace to 10 cm / south-southwest wind, 15-30 km/h / alpine high temperature -2 C / freezing level 1500 mFRIDAY: Mix of sun and cloud / southwest wind 10-20 km/h / alpine high temperature -2 C / freezing level 1600 mSATURDAY: Snow, 10-20 cm / south-southwest wind, 15-40 km/h / alpine high temperature -2 C / freezing level 1400 m

Avalanche Summary

On Monday, natural storm slab avalanches to size 2 were observed on northerly aspects around 2200-2400 m in the Whistler Backcountry, initiating from steep, lee start zones. Four skier-triggered avalanches (size 1.5-2) in the Whistler Backcountry were reported on Monday, including this Decker Main MIN report here. These similar avalanches occurred in northerly alpine terrain and below a ridge feature.On Sunday, avalanche control work with explosives triggered mostly small storm slabs (size 1-1.5) and cornices in alpine and treeline; these avalanches failed on the storm snow - melt-freeze crust interface.On Saturday, small (size 1-1.5) storm slabs and wind slabs were reactive to skier traffic. Cornices were reactive to explosives and triggered large (size 2) slab avalanches as they fell on the slopes below.

Snowpack Summary

Up to 15 cm wind and temperature affected snow overlies a crust on most aspects and a dry, settled snowpack on north-facing alpine terrain. In the alpine and upper treeline, wind loaded pockets up to 40 cm deep have developed around ridge crests and northerly terrain. Expect a snowpack that changes with elevation and through the day, between 1800 and 1200 m sun and warm temperatures through the day are producing a moist snowpack. Below, 1200 m the snow is melting rapidly. With spring conditions, the avalanche hazard will fluctuate greatly depending on the strength of the overnight freeze and how quickly the snowpack is warmed up each day.

Problems

Storm Slabs

Recent snowfall, wind and continued flurries have formed slabs around ridge crests and into the alpine. Use caution around cornices, lee features, and steep, convex slopes.

Be careful with wind-loaded pockets, especially near ridge crests and roll-overs.Expect conditions to change rapidly with elevation.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 1.5

Loose Wet

The recent snow will moisten quickly if the clouds clear or freezing levels rise. Loose wet avalanches can become dangerous quickly, so use added caution if the snow is moist or the sun comes out.

Cornices become weak with daytime heating, so travel early on exposed slopes.Avoid sun-exposed slopes and overhead exposure during periods of intense sun.Use extra caution on slopes if the snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Apr 11th, 2019 2:00PM