Avalanche Forecast

Issued: Mar 3rd, 2023 4:00PM

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

Avalanche Canada dnylen, Avalanche Canada

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Fresh wind slabs will be easy to trigger as they form. Recent snow will reverse load from northerly winds making windslabs in typically sheltered areas.

Summary

Confidence

Moderate

Avalanche Summary

Since the storm cleared up on Thursday, our field team observed a natural avalanche cycle up to size 3 from the highway in the inland areas around Paddy peak. We suspect that some of these may include step-downs to buried weak layers.

Our field team also observed new windslab avalanches up to size 2 and loose snow sluffing from steep alpine terrain around the White Pass.

Snowpack Summary

30-50 cm of recent snow has been stiffened at the surface in the high alpine and transported into wind slabs by moderate winds at all exposed elevations. At lower elevations, the recent snow has settled in Thursday's mild temperatures.

The mid snowpack is generally hard with a couple of crusts buried 60+ cm and 100+ cm deep, these have been problematic on north to east aspects as high as 1700 m, where they are covered in an overlying layer of weak surface hoar crystals. In inland areas these weak layers are closer to the surface and are easier to trigger.

Recent large avalanches are suspected to have run on the deeper of the two layers.

Weather Summary

Friday night

Possible Flurries. Moderate northeasterly wind. -18 ºC.

Saturday

Partly cloudy. Northeast wind 30 km/h except 40 km/h at valley bottom. Alpine temperature -20 ºC.

Sunday

Clear. Moderate to strong northeasterly outflow wind with ridge top speeds nearing 60 km/h. Alpine high -20 ºC.

Monday

Mostly sunny. Strong northeasterly outflow wind. Alpine temperatures climbing to -14 ºC.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be especially cautious as you transition into wind affected terrain.
  • Stay off recently wind loaded slopes until they have had a chance to stabilize.
  • Seek out sheltered terrain where new snow hasn't been wind-affected.
  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Wind Slabs

An icon showing Wind Slabs

Recent snow and wind have formed deep wind deposits in leeward terrain features. They will likely remain reactive Saturday. Watch for shooting cracks in stiffened or drifted snow as an indicator of instability.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

A weak layer of surface hoar and/or facets buried ~100 cm deep has produced occasional large, widely propagating avalanches on north to east aspects above 1500 m. Some avalanches have been remotely triggered from hundreds of meters away! A layer at this depth may not show obvious signs of instability. Best to avoid steep or unsupported high consequence alpine terrain.

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

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 3

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

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