Avalanche Forecast

Issued: Apr 10th, 2021 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Cornices.

Avalanche Canada ahanna, Avalanche Canada

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Wind slabs may remain sensitive to triggering Sunday. The sun can pack a punch at this time of year and the new snow will be particularly sensitive to it. Be ready to back off sunny slopes before the snow surface is moist or wet.

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

A ridge of high pressure sets up over the province. Freezing levels are forecast to steadily rise through the week.

Saturday night: Partly cloudy. Wind easing to light northwest. Alpine temperature around -12. Freezing level valley bottom.

Sunday: Mix of sun and cloud. Light northwest wind. Alpine temperature around -10. Freezing level 1000 m.

Monday: Sunny. Light to moderate northeast wind. Alpine temperature around -5. Freezing level 1600 m.

Tuesday: Sunny. Moderate northeast wind. Alpine temperature around -3. Freezing level 1900 m.

Avalanche Summary

We have not received any reports of avalanche activity since Wednesday when the North Rockies Field team reported and wind slab size 1 from an East aspect at treeline. Since Friday wind slabs have been reported to be stubborn.. 

In neighboring North Columbia region, most activity in the recent snow has been loose snow avalanches up to size 2. Wind slabs have shown quite limited reactivity in the last couple of days, the odd ski cut producing size 1-1.5. A couple of natural cornice failures size 2.5 did not trigger slabs on slopes below.

Snowpack Summary

20-40 cm of recent snow may have formed pockets of wind slab on leeward slopes and behind terrain features. On North aspects in the alpine, the recent snow sits on dry wintery snow surfaces and possibly surface hoar on wind-sheltered slopes. Elsewhere, it sits on a series of melt-freeze crusts on all aspects below 1900 m and southerly aspects to mountain top. Reports indicate snow is bonding well at these interfaces.

The recent warm weather is expected to have helped old persistent weak layers heal, including a few crusts buried over the last month as well as a facet layer 150 cm deep from the mid-February cold snap.

Terrain and Travel

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Wind Slabs

An icon showing Wind Slabs

Recent snow and wind have formed wind slabs in immediate lees of ridge crests and roll-overs at upper elevations. They may remain sensitive to triggering Sunday.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

An icon showing Cornices

Cornices are especially fragile this time of year, especially when the sun is out. Cornice falls are dangerous on their own and they can also trigger slabs on slopes below.

Aspects: North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 11th, 2021 4:00PM

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