Avalanche Forecast

Issued: Mar 16th, 2019 4:40PM

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

Avalanche Canada ghelgeson, Avalanche Canada

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The heat is on and the game is changing. Direct sun and steadily warming temperatures are expected to destabilize the upper 10 to 40 cm of snow and a natural avalanche cycle is possible. Look up and avoid travel under avalanche paths and cornices.

Summary

Confidence

Low -

Weather Forecast

The first big warm up of the season really begins to flex on Sunday. Say goodbye to any kind of temperature driven overnight re-freeze for the next few days. This weather event is going to have a pretty significant impact on our snowpack.SATURDAY NIGHT: Freezing level rising to 2000 m, light west/northwest wind, no significant precipitation, no overnight re-freeze.SUNDAY: Clear skies, light variable wind, freezing level skyrocketing to near 3000 m, no precipitation, no overnight re-freeze.MONDAY: Clear skies, light southeast wind, freezing level holding at 3000 m, no precipitation, no overnight re-freeze.TUESDAY: Clear skies, moderate southeast wind, freezing level lowering to 2800 m, no precipitation, no overnight re-freeze.

Avalanche Summary

On Friday a skier triggered a small wind slab at treeline that resulted in a broken leg. A few small wind slabs were observed on north facing alpine terrain and some natural cornice failure is beginning to be be observed.On Wednesday a skier remote triggered a size 2 wind slab on a northeast facing alpine slope at 2000 m with a crown 40 cm in depth. There are some great photos in this MIN of a size 2.5 wind slab that was skier triggered on a north facing slope on the Slalok/Matier Glacier. As we enter a period of increasing warming it's worth reminding ourselves that glide cracks are to be avoided at all times. They're incredibly unpredictable and when they fail, they often fail big. Glide avalanche concerns are especially important to consider in the Coquihalla area. A recent social media post from a professional in this part of the region does a great job of highlighting the issue. (Link here)This avalanche was reported from the Duffey Lake area on Tuesday. It indicates the nature of the bond between the recent storm snow and old surfaces below may be poor. Most other recent reports from this region have been of small loose snow avalanches.

Snowpack Summary

Light amounts of new snow have been redistributed by southwesterly and northerly winds, potentially creating some unusual wind slabs, including on south-facing slopes. Beneath this recent snow you may find hard wind-affected snow at higher elevations, soft and faceted snow in shaded and sheltered areas, and melt-freeze crusts on southerly slopes. The middle and lower snowpack is generally well-settled. For Sunday, we're most concerned about the upper 10 to 40 cm of snow.The bigger questions are deeper in the snowpack. After Saturday night, we're not expecting an overnight re-freeze for at least a few nights. That's going to allow the snowpack to warm and start freeing up a lot of water which acts like lubrication. When it doesn't freeze overnight, this process gets turbo-charged. Could multiple hot days and warm nights wake up deeply buried weak layers that we haven't thought about for awhile? We're not sure, but now is probably a time to let the mountains do their thing from afar and check back in when the freezing level returns to seasonal norms which could happen by next weekend.

Problems

Wind Slabs

An icon showing Wind Slabs
Clear skies & warm temperatures are expected to destabilize the upper 10 to 40 cm of snow which could begin failing naturally. If you're going riding Sunday, go super early, seek out higher elevation shaded aspects and make an early exit.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Back off slopes as the surface becomes moist or wet with rising temperatures.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Loose Wet

An icon showing Loose Wet
Loose wet activity is expected to continue and the shaded aspects may start producing loose activity too, even at upper elevation. Cornices are going to begin to loosen up and you don't want to be under one of these monsters when they fail.
Loose avalanches may start small but they can grow and push you into dangerous terrain.Cornices become weak with daytime heating or solar exposure.Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Mar 17th, 2019 2:00PM

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