Avalanche Forecast

Issued: Apr 22nd, 2018 3:47PM

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

Weather Forecast

A ridge of high pressure will develop for the forecast period bringing sunny skies and light ridgetop winds. The freezing level will hover around 2600m on Monday, 2800m on Tuesday and 3500m by Wednesday.

Avalanche Summary

No new avalanches have been reported although I'm sure there was a round of wind slab activity on Saturday in response to Friday night's snow and wind. I'm sure the new snow will be quick to settle and gain strength in the coming days. 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

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.

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.

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

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.

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

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

New snow and strong winds from Friday night and Saturday have formed wind slabs in upper elevation lee terrain. Although they're expected to gain strength quickly, I'd remain cautious around ridge crests and in gullies.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Apr 23rd, 2018 2:00PM