Avalanche Forecast

Issued: Mar 19th, 2023 3:00PM

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

Avalanche Canada JMackenzie, Avalanche Canada

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Skiers had a close call near Mt Birdwood on Saturday on a sun exposed slope. Check out the MIN for more details. The March sun packs a punch and can start to destabilize the snow in as little as 30 minutes.

Summary

Confidence

Moderate

Avalanche Summary

On Saturday skiers triggered a size 2.5/3 avalanche on a sun exposed slope near Mt Birdwood. This avalanche failed as the third skier crossed the slope and was triggered before the sun crust had started to break down. The slab was 30 to 80cm deep, failing on facets. Further details can be found on the MIN.

Snowpack Summary

The fresh snow from last week has largely escaped the wind.....so far. Many areas still have soft snow, but expect sun crusts on solar aspects at all elevations where the terrain is steeper than about 20 degrees. The strong late March sun is melting these surface crusts and destabilizing the slopes (see the Avalanche Summary for a close call on Saturday). There are previously formed wind slabs in alpine areas, so keep an eye out for these in lee and cross-loaded features. The midpack remains highly variable with areas of more than 100cm of total snowpack being supportive, but in shallower areas ski penetration can still be to ground. The good old facets and depth hoar still lurk at the bottom of the snowpack and present an ongoing concern for full-depth avalanches.

Weather Summary

Monday will bring a mix of sun and cloud, with the possibility of very light flurries at some point during the day. Freezing levels will rise to 2000m with ridgetop temps near -3C with light NE winds.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Cornices become weak with daytime heating or solar exposure.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

Wind Slabs

An icon showing Wind Slabs

Watch for wind slabs in immediate lees along ridgelines and in gullied terrain, especially at higher elevations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

The alpine is still variable in total amounts of snow but the basal layers haven't changed. The entire lower half is either facets or depth hoar. Thin weak areas should be treated as suspect and avoided.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Mar 20th, 2023 4:00PM