Archived

Avalanche Forecast

Feb 23rd, 2013–Feb 24th, 2013

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

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

Regions: Kootenay Boundary.

Avalanche danger is lower than posted in areas with minimal recent snow.

Confidence

Poor - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Sunday: Moderate to strong W winds. Light to moderate snow, starting late in the day. Alpine temperature around -4.Monday: Light to moderate NW winds. Light snow. Alpine temperature around -8.Tuesday: Light SW winds. Light snow. Alpine temperature around -11.

Avalanche Summary

A natural cycle to size 2.5 occurred overnight Friday. Explosives testing produced several more slabs to size 2.5 around treeline elevations on Saturday. These avalanches either failed within the storm snow or on a crust below the storm snow.

Snowpack Summary

Up to 55 cm snow now overlies weak interfaces buried in mid-February (mainly surface hoar/ sun crust layers). The storm slab above these interfaces has the potential for wide propagations and surprisingly large avalanches, especially where winds have shifted the snow into slabs in the lee of terrain breaks. Older snowpack weaknesses buried in the upper snowpack (Feb 4th and Jan 23 surface hoar/facet/sun crust layers) are still being tracked by professionals. There is the potential for triggering one of these deeper layers with a large trigger like an avalanche in motion, or from a thin-spot trigger point. The lower snowpack is generally well settled.

Avalanche Problems

Storm Slabs

Loading from new snow and wind has increased the avalanche danger. The presence of weak layers buried in the upper snowpack means there is a risk of triggering surprisingly large slabs.

Avoid freshly wind loaded features.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Give cornices a wide berth when travelling on or below ridges.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5