Avalanche Forecast

Issued: Apr 21st, 2018 3:58PM

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

jlammers, Avalanche Canada

Kootenay Boundary.

Warming and solar radiation will drive the avalanche danger in the coming days. Watch for conditions that change throughout the day, and be cautious of overhead hazards.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

A ridge of high pressure will develop for the forecast period bringing clear skies and light ridgetop winds. The freezing level will hover around 1800m on Sunday, 2400m on Monday and then 3100m on Tuesday.

Avalanche Summary

No new avalanches have been reported. I'm sure there was a round of wind slab activity on Saturday in response to Friday night's snow and wind, although I'm sure the new snow will settle and gain strength in the coming days. Loose wet avalanches and cornice falls are expected to become problematic with warming and solar radiation forecast for Sunday and Monday.

Snowpack Summary

New snow and wind from Friday night and Saturday likely formed relatively small wind slabs in upper elevation lee terrain. Depending on aspect and elevation, the new snow likely overlies a melt-freeze crust or settled storm snow from earlier in the week.Numerous other melt-freeze crusts exist in the upper snowpack from rain, sun, and warming during the spring season. The mid and lower snowpack are generally well-settled and strong while melt-freeze conditions exist on all aspects below treeline.

Problems

Loose Wet

Warming and solar radiation over the next few days are expected to trigger loose wet avalanches, especially in steep, sun-exposed terrain. Loose wet avalanches can be pushy and entrain mass quickly.

Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Cornices

Warming and solar radiation may also cause large cornices to fail. Cornice failures may be dangerous by themselves, but they could also trigger a large avalanche on the slope below.

Give cornices a wide berth when travelling on or below ridges.Avoid areas with overhead hazard.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

Lingering wind slabs from Friday night may remain reactive in high elevation lee terrain. Watch for triggering behind ridgecrests and steep rolls.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Apr 22nd, 2018 2:00PM