Avalanche Forecast

Issued: Mar 22nd, 2014 9:35AM

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

rbuhler, Avalanche Canada

Cariboos.

Expect to see sunny breaks over the next few days. Brief periods of solar radiation could be enough to trigger stubborn persistent slabs or cause cornice failures. Conservative route selection remains crucial at this time.

Summary

Confidence

Fair

Weather Forecast

Light flurries Sunday morning are expected to taper off early in the day.Â A weak ridge of high pressure will build Sunday night and should persist for most of Monday. Some weak disturbance may bring light flurries for Monday night but Tuesday is expected to be mainly dry.Â The next organized system is expected Tuesday night or Wednesday morning. Sunday: Mostly cloudy, flurries 0-2cm, freezing level am: surface pm: 600-800m, ridgetop wind: light NWMonday: A mix of sun and cloud, freezing level am: surface pm: 700-1000m, ridgetop wind: light variableMon. Night/Tuesday: Flurries overnight 3-8cm, freezing level am: 800m pm: 1600m, ridgetop wind: 20-40 km/h SE-SW

Avalanche Summary

Reports from Friday include a natural size 2.5 storm slab avalanche, a natural size 3 wind slab, natural cornice releases, and solar triggered sluffing from steep features.Â Generally, we are still seeing relatively small inputs, like periods of strong winds or brief sunny breaks, trigger deeper persistent slab avalanches. Many of these events have occurred on southerly aspects from slopes in the alpine or at treeline. Extra caution is advised when the sun is out.

Snowpack Summary

A 40-70cm storm slab sits on the mid-March crust/surface hoar layer. There may be a variety of layers within the storm slab including thin sun crusts, graupel balls, and maybe even small surface hoar from brief clearings overnight. Expect wind slabs in exposed lee and cross-loaded terrain from recent SW-W winds. A couple other notable persistent weakness layers remain a concern in the mid-snowpack. The surface hoar/sun crust combo buried in early March is now typically down around 1m. The early-February surface hoar/facet/crust combo is down around1.5m and widespread throughout the region. Smaller avalanches stepping down and cornice falls have the potential to initiate an avalanche on this deeply buried weak layer. The mid and lower snowpack remains weak and facetted in areas with a relatively shallow snowpack.

Problems

Storm Slabs

Weaknesses exist within or under the recent storm snow and could be triggered by the weight of a rider, particularly in steep wind-loaded terrain. Also, expect some loose wet activity on solar aspects when the sun is out.

Be cautious as you transition into wind affected terrain.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The early March sun crust/surface hoar combo should not be underestimated. While there's a lot of uncertainty and complexity surrounding this layer, it's important to note that human triggering is most likely at treeline.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Use conservative route selection, stick to moderate angled terrain with low consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Deep Persistent Slabs

The early February weak layer is still active and has produced some stunning avalanches recently. Very large avalanches may result from smaller avalanches stepping down, a cornice fall, or a rider finding the sweet spot.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for large, deep avalanches due to the presence of deeply buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 23rd, 2014 2:00PM