Archived

Avalanche Forecast

Mar 16th, 2015–Mar 17th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

If solar radiation is strong on Tuesday, the Avalanche Danger may rise to High. Be conservative in your terrain selection as the snowpack adjusts to the shock of recent heavy rain, snow, and now sun.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

Mostly clear skies are forecast for Tuesday as a ridge of high pressure strengthens. On Tuesday night and Wednesday, expect light snowfall (up to 10cm) as a weak front spreads moisture to the region. On Thursday, the region should see a mix of sun and cloud with possibility of snowfall towards the end of the day. Winds should remain generally light, ramping up to moderate from the southwest as Thursday's system rolls in. Freezing levels should hover around 1800m on Tuesday, 1900m on Wednesday and 2000m on Thursday.

Avalanche Summary

At the time of publishing this bulletin no new avalanche activity had been reported. My best guess is that there was a healthy round of storm slab activity in response to all the new snow and wind on Sunday. Looking forward, I`m sure the new storm slab will remain sensitive to human triggering in high elevation, wind-exposed terrain. Also, sun on Tuesday will likely spark a round of loose wet/ wet slab avalanche activity on steeper, sun-exposed slopes.

Snowpack Summary

Heavy rain on Saturday soaked the snowpack up to ridge tops. On Sunday, heavy snowfall (up to 35cm) and southwest winds developed new storm slabs that may be easy to trigger, and may allow for long propagations where they are sitting on a crust/facet combination. The most prominent feature in the snowpack is the thick late-February crust located about 20cm below the recent storm snow. Limited reports suggest this crust is breaking down in some areas, while it remains supportive all the way to ridge crest in other spots. Deeply buried persistent weak layers still exist in the snowpack. These layers have not been reactive lately, however the extremes of warm weather followed by heavy loading due to rain then followed by snow, make it difficult to assess how the snowpack will respond.

Avalanche Problems

Loose Wet

The new snow may fail as a pushy loose wet avalanche when it sees direct sunlight for the first time. Keep your eye on the thermometer and watch your overhead hazard as these avalanches may travel long distances and entrain mass quickly.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be alert to conditions that change with aspect, elevation and time of day.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Storm Slabs

Heavy snowfall on Sunday has created deep new storm slabs which will likely remain sensitive to human triggering, especially in higher elevation lee terrain. Recent snow and wind has also created weak and fragile cornices.

The new snow will require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4