Avalanche Canada cgarritty, Avalanche Canada

Northwest Coastal Avalanche Forecast

Apr 19th, 2019 4:47PM

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

Stronger sunshine and warmer temperatures are the concern for Saturday. New snow that sees sun for the first time is expected to shed easily, whether naturally or with light triggers. Please post your observations to the Mountain Information Network!

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday night: Clear with cloudy periods. Light to moderate northwest winds.

Saturday: A mix of sun and cloud. Light variable winds. Alpine high temperatures around -2 with freezing levels to 1200 metres.

Sunday: Cloudy with scattered flurries bringing approximately 5 cm of new snow, increasing overnight. Moderate south winds increasing overnight. Alpine high temperatures around -1 with freezing levels to 1300 metres.

Monday: Cloudy with continuing flurries bringing 10-20 cm of new snow and new snow totals to 20-35 cm. Moderate rain below about 1200 metres. Precipitations easing overnight. Strong south winds, easing over the day. Alpine high temperatures around 0 with freezing levels to 1500 metres.

Avalanche Summary

No new avalanches have been reported in the region. Please submit your observations to the Mountain Information Network.

Snowpack Summary

5-10 cm of new snow fell over Thursday night, bringing new snow totals since Tuesday to approximately 20-40 cm. Moderate to strong southwest winds are expected to have formed reactive wind slabs with the new snow over the same time period.

The new snow has buried another wind-redistributed 5 to 20 cm of snow that fell on Saturday. This previous snow remains dry on high elevation north facing slopes, while a 5 to 10 cm melt freeze crust can be found instead on all other aspects.

The April 4th crust is now down 30 to 100 cm on high elevation north facing slopes. Surface hoar and facets were previously observed on this crust and it recently produced sudden results in snowpack tests. It is uncertain whether it became involved in any natural avalanche activity during the past few stormy days.

At lower elevations, ongoing warm weather has been promoting isothermal snowpack conditions and melting the snowpack away.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Strong winds likely packed much of our recent snow into wind slabs focused on lee (north to east) slopes. This problem increases with elevation and proximity to the coast. Slabs that formed over crust at the previous surface may be touchy.

  • Look for signs of instability. Shooting cracks and recent avalanches indicate unstable conditions.
  • Use caution around recently wind loaded features, especially if they are being warmed by the sun.

Aspects:

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

Elevations:

Alpine, Treeline.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely

Expected Size

1 - 1.5

Sunshine is in the forecast for the first time after a several days of steady snowfall. Expect recent snow to shed easily from steep slopes that see direct sun. This may occur naturally or with a human trigger.

  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.
  • Use extra caution on slopes if the snow is moist or wet.

Aspects:

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

Elevations:

Alpine, Treeline.

Valid until: Apr 20th, 2019 2:00PM