Avalanche Forecast

Issued: Mar 1st, 2016 8:18AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Persistent Slabs.

ccampbell, Avalanche Canada

South Columbia.

Touchy and growing storm slabs will keep avalanche danger elevated this week. Riding should be great, but a conservative approach is recommended. Stick to simple terrain.

Summary

Confidence

High

Weather Forecast

WEDNESDAY: A relatively dry day is expected with another few cm of accumulation before tapering off late in the day. Freezing levels are expected to reach 1600m with light southwesterly ridgetop winds. THURSDAY: Periods of snow with 3-5cm of accumulation expected throughout the day. Freezing levels reaching 1800m with light to moderate southwesterly ridgetop winds. FRIDAY: Another 3-5cm of accumulation expected throughout the day. Freezing levels reaching 2000m with light to moderate southwesterly ridgetop winds.

Avalanche Summary

Reports from Monday include a brief natural wind slab avalanche cycle primarily in the Monashee Mtns., with avalanches up to Size 2.5 running running early Monday morning in response to gusty winds. Elsewhere, 10-40cm thick fresh storm and wind slabs were highly reactive to human triggers with several direct and remotely triggered avalanches up to Size 2. These fresh storm and wind slabs should increase in size and sensitivity and become much more widespread as they build throughout the week.

Snowpack Summary

20-40 cm thick fresh storm slabs are bonding poorly to on a crust on sun-exposed slopes and surface hoar on shady and sheltered slopes. Thicker and touchier wind slabs are lurking throughout exposed terrain at and above treeline. A weak layer of surface hoar and/or a sun crust buried February 21 is now 50-80cm below the surface. Where it exists, this layer may become reactive to human triggers as the overlying slab develops. The surface hoar and/or crust layer buried February 10 is now down 80-130cm. This layer was less reactive over the weekend with cooler temperatures, but remains a concern for large triggers like cornice falls or a smaller slide in motion. Cornices are large and potentially weak and should be avoided where possible.

Problems

Storm Slabs

Fresh storm slabs are primed for human triggering. Particularly touchy wind slabs are lurking below ridge crests, behind terrain features and in cross loaded gullies.

Choose well supported terrain without convexities.>Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

Heavier triggers such as cornice falls, groups of people, or smaller avalanches stepping down, or lighter triggers (such as a person) in the wrong spot may be enough load to trigger a crust and/or surface hoar layer down around a metre.

Caution around convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Mar 2nd, 2016 2:00PM