Avalanche Forecast

Issued: Dec 13th, 2013 8:17AM

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

jabbiss, Avalanche Canada

Cariboos.

Forecast storm snow, strong winds and warm temperatures will elevate the danger rating to HIGH in the alpine for Saturday.

Summary

Weather Forecast

Friday night and Saturday: The pacific front makes landfall and spills over into the interior by early Saturday. Moderate to locally heavy snowfall (Bowron Lakes a potential hot spot). Winds strong-extreme westerly, and freezing levels rising to 800m. Possibility of an inversion around 1500m.Sunday: The frontal system will move through the north Saturday night and south on Sunday. Light to moderate precipitation amounts and strong/extreme westerly winds. Freezing level will hover around 1300m.Outlook for Monday: Strong northwesterly flow will prevail over the northern interior and light precipitation is expected.

Avalanche Summary

No new avalanches reported. The lack of observations likely speaks more to the lack of observations rather than actual conditions. With forecast snowfall, winds and warm temperatures, a spike in avalanche activity is likely through the weekend.

Snowpack Summary

Snowpack depths are likely to vary across the region. At treeline, the average depths of snow is 120-150cm, seasonably below average.The forecast suggests moderate to heavy amounts of new, warmer and denser snow will fall on top of the recent light snow that continues to add load above various buried weak layers. This combination includes wind slabs, crusts, surface hoar, and facets. Rising temperatures forecast over the next few days are expected to consolidate the storm slab above these buried weak layers. It may be difficult to determine when the slab will become more sensitive to light triggers like skiers and sledders. These weak layers are expected to be persistent, although in many areas the upper slab is not yet stiff enough for slab avalanches. When temperatures rise, and we get additional snow, expect this interface to become more reactive.Digging deeper, in the mid-pack, a couple persistent weak layers (surface hoar and facets) are found which formed in mid and late November. Near the base of the snowpack, a early season rain crust exists. The continuous loading of new snow and the rising temperatures may be enough to wake up these previously dormant layers.

Problems

Storm Slabs

Forecast warm, dense snow will likely create a upside down snowpack scenario with widespread storm slabs. This may be particularly touchy where it overlies buried weak layers; surface hoar or facets. Strong west winds may create touchy wind slabs.

Minimize exposure during periods of heavy loading from new snow, wind.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Be alert to conditions that change with elevation, precipitation, temperature and wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

3 - 4

Persistent Slabs

Continual loading of new snow over a variety of persistent weak layers found in the mid snowpack may eventually wake up these layers. The likelihood will increase if the forecast spike in temperatures holds true.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

3 - 5

Valid until: Dec 14th, 2013 2:00PM