Avalanche Forecast

Issued: Apr 23rd, 2018 4:09PM

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

cgarritty, Avalanche Canada

Kootenay Boundary.

Surface instabilities and cornice hazards should be firmly on your radar as you travel. Expect stability to deteriorate over the course of each day.This is our last regular forecast of the season and will expire on April 25.

Summary

Confidence

Moderate -

Weather Forecast

Tuesday: Sunny. LIght south winds, moderate at ridgetop. Freezing level to 3400 metres. Alpine high temperatures around +8. Weak overnight cooling.Wednesday: Sunny. Light northwest winds. Freezing level rising from about 2700 to 3500 metres by evening. Alpine high temperatures around +9.Thursday: Sunny. Light south winds. Freezing level to 3700 metres with alpine high temperatures around +11.

Avalanche Summary

No new avalanches have been reported although there was likely a round of wind slab activity on Saturday in response to Friday night's snow and wind. The new snow will likely be quick to settle and gain strength in the coming days. With that said, loose wet avalanches and cornice falls are expected with warming and solar radiation forecast for this week. Although less likely, warming may also trigger unexpectedly deep and destructive slab avalanches failing on weaknesses which formed earlier in the season.

Snowpack Summary

A new surface crust is likely to exist on all but north aspects in the high alpine and is expected to undergo melt-freeze cycles with daily warming and overnight cooling. Below the surface, new snow and wind from Friday night and Saturday 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; however, weaknesses deep within the snowpack have the potential to 'wake-up' in isolated terrain with forecast warming and solar radiation, or with a large cornice trigger.

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

Very Likely

Expected Size

1 - 2.5

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 - Likely

Expected Size

1.5 - 3

Valid until: Apr 24th, 2018 2:00PM