Avalanche Forecast

Issued: Mar 2nd, 2020 3:00PM

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

Avalanche Canada shorton, Avalanche Canada

Regular pulses of new snow and strong wind will form wind slabs in open terrain. Stick to sheltered terrain free of overhead hazards.

Summary

Confidence

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

Stormy weather continues until Thursday, then things cool off.

MONDAY NIGHT: Mainly cloudy, light flurries with 5 cm of new snow, steady blowing snow, moderate wind with strong gusts from the south, alpine temperatures drop to -10 C.

TUESDAY: Scattered flurries with 5-10 cm of snow, moderate wind from the southwest, alpine high temperatures around -7 C.

WEDNESDAY: Scattered flurries continue with another 5-10 cm of snow, strong wind from the south, alpine high temperatures around -10 C.

THURSDAY: Storm eases, mix of sun and cloud, light to moderate wind from the north, alpine temperatures drop to -20 C.

Avalanche Summary

There has likely been natural avalanche activity on wind loaded slopes since the arrival of a storm on Saturday night, however there have been limited field observations to confirm this.

On Saturday, prior to the storm, there were a few reports of small (size 1) skier triggered avalanches on small slopes. One of these was triggered on southeast alpine slope and ran on a sun crust 40 cm below the surface, and another one was on a convexity in an clearing in the trees.

Steady snowfall and wind will continue to form reactive wind slabs this week.

Thanks for all the excellent Mountain Information Network reports over the weekend!

Snowpack Summary

A storm arriving Saturday afternoon continues to hammer White Pass with strong south wind, causing extensive wind slab and cornice growth in open terrain. Mild temperatures have likely caused last week's 30-50 cm of powder to settle rapidly. On open south-facing slopes the storm snow sits above a sun crust.

At White Pass the snowpack is roughly 200 cm thick with a strong mid and lower snowpack. Thin snowpack areas to the east of White Pass may have a lower snowpack composed of sugary faceted grains, capped by a breakable melt-freeze crust and wind-affected snow.

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
  • Seek out sheltered terrain where new snow hasn't been wind-affected.

Problems

Wind Slabs

An icon showing Wind Slabs

Strong south wind will continue to form thick wind slabs in the alpine and open treeline terrain this week. These slabs will be reactive to human triggering, especially on freshly loaded slopes. Also be aware of large cornices that could trigger slabs on the slopes below.

Aspects: North, North East, East, South East, West, North West.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Valid until: Mar 4th, 2020 4:00PM