Avalanche Forecast

Issued: Mar 12th, 2018 4:30PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Loose Wet and Wind Slabs.

Avalanche Canada mgrist, Avalanche Canada

Avalanche danger will increase on sunny slopes, where wet loose avalanches are very likely. Concern is increasing for persistent slabs and cornices.See the Forecaster's Blog for more: http://www.avalanche.ca/blogs/2018-03-09-first-big-warm-up

Summary

Confidence

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

Weather Forecast

Sunny and warm until light precipitation arrives late Wednesday. TUESDAY: Mainly sunny with some thin cloud. Moderate southeast winds, increasing over the day. Freezing level to 2500 metres with alpine high temperatures of +4.WEDNESDAY: Cloudy with rain or wet flurries in the afternoon (2-5 cm possible). Light to moderate south west winds. Freezing level falling to 1700 metres late in the day, with alpine high temperatures of +2.THURSDAY: Scattered flurries (2-5cm). Light southerly winds. Freezing level around 1500 metres with alpine high temperatures around 0 degrees.

Avalanche Summary

Reports from throughout the weekend included many wet loose avalanches to size 1.5. These occurred in steeper terrain on sunny aspects. On Friday, numerous recent wind slab releases were observed to have run naturally up to size 2.5 on steeper north aspects above 2000m.Avalanche activity is expected to increase as we move into a period of intense sun and prolonged warming. Predictable wet loose avalanches from steep, sunny terrain should be easy to manage. A trickier problem will gradually emerge as warmth penetrates into the snowpack to tickle deeper persistent weak layers that have been dormant for awhile now in the Cariboos. Tuesday will be a time to avoid exposure to large sunny features and keep well away from corniced slopes.

Snowpack Summary

The last snowfall was Thursday's storm, which brought 20-30 cm of new snow by Friday morning. Since then, isolated wind effect has created patchy wind slabs at higher elevations, but really, the main story has been the sun's effect on south and west facing slopes. Daytime heating has resulted in moist or wet snow on sunny aspects, freezing to form a crust overnight. This newer snow overlies well-settled older snow from regular snowfalls over the past couple of weeks. Although several layers of sun crust can be found within this older storm snow on solar aspects, recent snowpack tests have not been producing concerning results in the upper snowpack.Persistent weak layers from early January and mid-December are still being reported by local operators. They are generally considered dormant, but could wake up with forecast warming, a surface avalanche stepping down, a cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets.

Problems

Loose Wet

An icon showing Loose Wet
Wet loose avalanches will be very likely in steep, rocky, sunny terrain. Warming could also wake up more deeply buried weak layers, creating a surprisingly large avalanche.
Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Choose regroup spots carefully, thinking about what is above you.

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

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2

Wind Slabs

An icon showing Wind Slabs
Wind slabs formed on many aspects during last week's storm and may remain reactive on Tuesday. Extra caution is needed on solar aspects where sunshine could act as a natural trigger with a buried sun crust as a sliding layer.
If triggered, large wind slabs may step down to deeper layers and result in very large avalanches.Pay attention to cornices and give them a wide berth when travelling on or below ridges.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Valid until: Mar 13th, 2018 2:00PM