Avalanche Forecast

Issued: Apr 19th, 2019 4:25PM

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

Avalanche Canada jsmith, Avalanche Canada

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Fresh storm slabs at upper elevations will likely be reactive to human triggers; especially in lee features below ridgetops.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY NIGHT: Clearing / Light, northwesterly winds / Alpine low -1 C / Freezing level 1800 m.

SATURDAY: Sunny / Light, northwesterly winds / Alpine high 0 C / Freezing level 2000 m.

SUNDAY: Sunny / Light, southwesterly winds / Alpine high 3 C / Freezing level 2400 m.

MONDAY: Sunny / Light, southwesterly winds / Alpine high 4 C / Freezing level 2500 m.

Avalanche Summary

Numerous small (size 1) skier triggered loose wet avalanches were reported on Thursday.

On Tuesday, two naturally triggered size 1.5 storm slab avalanches 25 cm deep were reported on northwest aspects 2200-2400 m.

Several recent natural slab avalanches up to size 2 have been reported on north and east aspects in the alpine. The suspected weak layer was either a crust or small surface hoar that was down 25-50 cm.

Snowpack Summary

20-30 mm. of rain has soaked the snowpack at treeline and below. The rain/snow boundary on Friday was around 2200 m. New snow amounts in the alpine will taper rapidly with elevation and likely equate to around 15-20 cm of moist snow at upper elevations adding to the 20-40 cm recent snow which overlies a crust everywhere except high elevation, north facing terrain where preserved surface hoar (weak, feathery crystals) may be present in isolated locations down 30-60 cm. A similar layer buried in early April is down 50-80 cm. Smaller storm slab avalanches may step down to one of these deeper weak layers.

Below treeline, snow is disappearing rapidly.

Problems

Storm Slabs

An icon showing Storm Slabs

Fresh storm slabs at upper elevations will likely be reactive to human triggers; especially in lee features below ridgetops.

  • Use small slopes without consequence to test the bond of the recent snow.
  • Pay attention to changing conditions with elevation/aspect.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2.5

Loose Wet

An icon showing Loose Wet

If temperatures remain warm, loose wet avalanches are still possible with strong solar radiation; especially in the alpine where there is new snow.

  • A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.
  • 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 - Likely

Expected Size

1 - 2

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