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Avalanche Canada cgarritty, Avalanche Canada

Northwest Coastal Avalanche Forecast

Apr 24th, 2019 4:21PM

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

Limited recent field observations mean that this forecast should be used to guide your initial assessment of conditions. See our 'Cold & Snowy' spring scenario for more on managing current conditions.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

Wednesday night: Cloudy with scattered flurries bringing a trace to 5 cm of new snow. Light southwest winds.

Thursday: Cloudy with sunny periods. Light variable winds. Alpine high temperatures around -5 with freezing levels to 1200 metres.

Friday: Cloudy with flurries bringing approximately 10 cm of new snow. Light to moderate south winds shifting southwest. Alpine high temperatures around -6 with freezing levels to 1000 metres.

Saturday: Sunny with cloudy periods. Light northeast or northwest winds. Alpine high temperatures around -3 with freezing levels to 1300 metres.

Avalanche Summary

Reports from the Bear Pass area on Wednesday showed diminishing natural avalanche activity with a few new size 2 (large) wind slab releases observed in steep leeward features in the alpine.

Reports from the same area on Monday described a natural avalanche cycle driven by new snow and strong winds. The cycle led with natural wind slab releases reaching size 3 (very large) in the morning and followed with wind slab releases decreasing in size and shifting to east aspects as winds became extreme and shifted west in the afternoon.

No new avalanches have been reported in the south of the region.

Please submit your observations to the Mountain Information Network.

Snowpack Summary

Another variable trace to 10 cm of new snow fell over Tuesday night, adding to 10-30 cm of new snow that fell Sunday night and Monday. Moderate to strong southwest winds are expected to have formed reactive wind slabs with much of this recent snow. The new snow sits on an older layer of settled storm snow from last week, which itself overlies a now 40-60 cm-deep melt freeze crust. This crust is widespread with the possible exception of high elevation north aspects. Most of our recent precipitation has fallen as rain at 1000 m and below.

Another widespread crust that formed in early April is down 50 to 100 cm. Weak layers of surface hoar and facets were previously observed on this crust on high elevation north facing slopes. At lower elevations, ongoing warm weather has been promoting isothermal snowpack conditions and melting the snowpack away.

Problems

Wind Slabs

Recent snowfalls coupled with bouts of strong southwest wind have likely developed new wind slabs at higher elevations. Expect snow amounts and the effects of wind loading to increase as you gain elevation.

  • Be cautious as you transition into wind affected terrain.
  • Look for signs of instability. Shooting cracks and recent avalanches indicate unstable conditions.

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 25th, 2019 2:00PM