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Avalanche Canada dsaly, Avalanche Canada

Sea to Sky Avalanche Forecast

Apr 23rd, 2019 3:00PM

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

Wind slabs may react to human triggers around ridges and immediate lee features. Loose wet avalanches remain a concern, especially on sunny slopes.

Summary

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT: Mostly cloudy, light to moderate west wind, alpine temperature -6 C, freezing level 800 m.

WEDNESDAY: Mix of sun and clouds, light northeast  wind, alpine temperature -1 C, freezing level 1800 m.

THURSDAY: Cloudy with sunny periods, light southeast wind, alpine temperature +1 C, freezing level 2000 m.

FRIDAY: Cloudy with sunny periods, light to moderate southwest wind, alpine temperature +1 C, freezing level 2000 m.

Avalanche Summary

On Saturday morning around the Whistler Backcountry, a natural wet loose avalanche cycle to size 2 was observed on all aspects from 1900-2200m. Wet slab avalanches to size 3 were observed on loaded northerly features in the alpine. Natural cornices failures to size 2 were also observed and explosives control work triggered cornices size 2-2.5. Further south in the region, cornices failing naturally triggered large (up to size 3) slab avalanches on the slopes below. Avalanche reports tapered Sunday.

More recently, isolated wind loaded pockets of moist slab have produced small propagations and loose wet avalanches are reported with daytime warming.

Snowpack Summary

In the alpine, up to 10 cm cold wind-affected snow is holding onto northerly aspects. Southerly winds have produced isolated drifts around ridges and in immediate lees at upper elevations, cornices have been touchy recently.

A crust is found on solar alpine slopes and all aspects below. Warm overnight temperatures are preventing strong crust recovery as you lose elevation. Expect thin surface crusts to break down quickly with daytime warming. Below treeline the snowpack is saturated and rapidly melting.

Problems

Wind Slabs

South-southwesterly winds have produced isolated pockets of snow around ridges and immediate lees. Cornices may be touchy, give them plenty of space.

  • Cornices may be touchy and could trigger wind slabs on slopes below.
  • Be careful with wind-loaded pockets, especially near ridge crests.
  • Use extra caution on slopes if the snow is moist or wet.

Aspects:

North, North East, East, South East, North West.

Elevations:

Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Loose Wet

The likelihood of loose wet avalanches will depend on the extent of overnight crust recovery and the pace at which the warms through the day.

  • Minimize overhead exposure and avoid steep slopes during periods of strong sun.
  • Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.

Aspects:

East, South East, South, South West, West.

Elevations:

Alpine, Treeline.

Likelihood

Possible - Unlikely

Expected Size

1 - 1.5

Valid until: Apr 24th, 2019 2:00PM