Avalanche Forecast

Issued: Mar 4th, 2020 12:00PM

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

Avalanche Canada ghelgeson, Avalanche Canada

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New snow and wind Thursday night into early Friday is expected to form fresh slabs that will likely be sensitive to human triggering, especially on Friday. Seek out wind sheltered terrain and watch for changing conditions as you gain elevation.

Summary

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system. Uncertainty is due to field data and reports showing a wide variation in conditions throughout the region.

Weather Forecast

Looks like we’ll be out of the storm’s bullseye, but Thursday into Thursday night could still produce some nice accumulations.

WEDNESDAY NIGHT: Moderate southwest wind, freezing level at valley bottom, no significant precipitation expected.

THURSDAY: Broken cloud cover, strong south/southwest wind, freezing level rising to about 1600 m, 5 to 10 cm of snow possible during the day with another 5 to 10 cm possible Thursday night.

FRIDAY: Broken cloud cover, light variable wind, freezing level at valley bottom, no significant precipitation expected.

SATURDAY: A few clouds, light variable wind, freezing level at valley bottom, no significant precipitation.

Avalanche Summary

On Tuesday our field team noticed a size 2 avalanche on a southeast facing slope at treeline. They also observed recent storm slabs that were 10 to 20 cm in depth, more details in this MIN.

On Monday natural wind slab avalanches to size 2 were reported on southwest & northwest facing slopes between 1500 and 1800 m. On Sunday a few small (size 1) human triggered slab avalanches were reported on north and east facing slopes (see photos in this Mountain Information Network report from a neighbouring part of the Cariboos). Natural avalanche activity was likely more extensive over the weekend given the intensity of the storms, but poor visibility would have limited observations.

Snowpack Summary

In the last week 30 to as much as 90 cm of storm snow has fallen across the region. The snow has been heavily affected by west/southwest wind throughout the storm which is reflected in the avalanche summary.

There are a couple of crusts beneath recent storm snow including a rain crust below 1200 m and sun crusts on south and west facing slopes.

Recent observations suggest the lower snowpack is strong and well-bonded in many parts of the region. However, given the large extent of the region it remains important to understand snowpack conditions in your local riding area. The Pine Pass area has a layer of surface hoar roughly 100 cm below the surface that was a problem around treeline elevations in mid-February, but appears have gained strength since then. The eastern slopes of the Rockies have many shallow rocky slopes that could harbour weak basal facets.

Cornices have grown large and should be given wide berth, especially if you're travelling on ridge lines.

Terrain and Travel

  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Make conservative terrain choices and avoid overhead hazard.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Storm Slabs

An icon showing Storm Slabs

The Thursday afternoon storm is expected to form new storm and wind slabs. Natural avalanche activity is possible Thursday night into early Friday morning. Human triggered slabs are likely Friday, especially on wind affected slopes at higher elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Mar 6th, 2020 5:00PM