Avalanche Forecast

Issued: Apr 19th, 2019 4:48PM

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 alpine ridgetops.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY NIGHT: Clearing / Light to moderate, northwesterly winds / Alpine low -6 C / Freezing level 1200 m.

SATURDAY: Sunny / Light, northwesterly winds / Alpine high -2 C / Freezing level 1800 m.

SUNDAY: Sunny / Light, southwesterly winds / Alpine high 1 C / Freezing level 2200 m.

MONDAY: Cloudy / Moderate, southwesterly winds / Alpine high 0 C / Freezing level 2100 m.

Avalanche Summary

No new avalanches were reported on Thursday.

On Tuesday, numerous naturally triggered size 2 persistent slab avalanches were reported on all aspects in the alpine.

Snowpack Summary

10-25 mm of rain has soaked the snowpack below treeline. The rain/snow boundary on Friday was around 2000 m. New snow amounts in the alpine will taper rapidly with elevation and likely equate to around 10-15 cm of moist snow at upper elevations adding to the 15-40 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 40-60 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 alpine ridgetops.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2.5

Loose Wet

An icon showing Loose Wet

If temperatures remain warm and the solar radiation is strong, loose wet avalanches are still possible at treeline and likely in the alpine where there is new snow.

  • A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.
  • Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

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