Avalanche Forecast

Issued: Mar 2nd, 2016 8:40AM

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

Moderate - Intensity of incoming weather systems is uncertain on Saturday

Weather Forecast

THURSDAY: Periods of snow with 5-10cm of accumulation expected overnight Wednesday and throughout the day Thursday. Freezing levels reaching 1800m with moderate to strong southwesterly ridgetop winds. FRIDAY: A mix of sun and cloud in the morning with light precipitation starting late in the day. Freezing levels reaching 2000m with moderate to strong southwesterly ridgetop winds. SATURDAY: Cloudy with flurries bringing another 5-15cm. Freezing levels steady around 2000m and strong southwesterly ridgetop winds.

Avalanche Summary

Reports from Tuesday include more evidence of the widespread natural storm and wind slab avalanche cycle early Monday primarily in the Monashee Mtns., with avalanches up to Size 3 running on surface hoar buried late February. Continued isolated natural avalanche activity occurred on Tuesday primarily in alpine areas with avalanches observed up to Size 2 in response to loading from fresh snow and wind. Elsewhere, 15-40cm 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

10-20cm of fresh snow adds to the now 30-60cm thick storm slabs, which are bonding poorly to on a crust on previously 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 close to a metre 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 likely down over a metre. This layer was less reactive over the weekend with cooler temperatures, but remains a concern for large triggers like cornice falls or a smaller avalanches stepping down. 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.

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

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.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Mar 3rd, 2016 2:00PM