Avalanche Forecast

Issued: Feb 7th, 2015 8:47AM

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

Avalanche Canada rbuhler, Avalanche Canada

Storm problems will persist on Sunday, especially at higher elevations. If the sun breaks through, solar triggered avalanches are expected. Conservative decision making remains critical and travel in avalanche terrain is not recommended.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Another pulse of moderate precipitation is expected Saturday overnight with freezing levels around 1500m. Precipitation should ease during the day on Sunday but light scattered flurries are expected to persist, at least in the morning. Broken or scattered sky cover is possible in the afternoon and some areas may see sun. Freezing levels should remain around 1500m. Alpine winds are forecast to be strong from the SW on Sunday morning and ease during the day. The next storm pulse is expected to arrive Sunday overnight and persist through the day on Monday. Freezing levels may drop Sunday overnight but this depends on the amount of clearing between the storm pulses. Freezing levels on Monday are uncertain and may be as low as 500m or as high as 1500m. Alpine winds are expected to be moderate from the SW. The end of the storms is forecast for early Tuesday. Lingering flurries and sunny breaks are both possible on Tuesday. Unfortunately, the warm air is expected to persist for several days following the end of the storm and freezing levels may remain unseasonably high.

Avalanche Summary

Observations from the Cariboos have been limited during the storm but several natural size 2 storm slabs were observed on Friday. In the North Columbia region, natural avalanches up to size 3.5 were reported on Saturday. On Sunday, natural avalanches remain likely at upper elevations where storm and wind loading continue. At lower elevations which have seen rain, natural activity is less likely but remains possible. Human-triggering remains very likely at higher elevations on Sunday. If the sun comes out on Sunday, solar aspects will likely see natural avalanche activity.

Snowpack Summary

50-80cm of recent storm snow has fallen over the late-Jan weak layer. Rising freezing levels during the storm have created upside-down snow conditions and highly reactive storm slabs. Rain has soaked the snow surface up to around treeline elevation. Strong SW winds have formed wind slabs in exposed leeward terrain features. The storm slab sits on an old rain crust at lower elevations, variable surface hoar, and/or wind affected surfaces at higher elevations. The mid-January surface hoar is typically down over 60-100cm and is still reactive in some areas. The mid-December weak layer is down 100 to 150cm. It has generally been unreactive but may wake-up with the new storm loading.

Problems

Storm Slabs

An icon showing Storm Slabs
Strong winds, heavy snowfall, and high freezing levels have created widespread storm slabs at higher elevations. Continued storm conditions will add to these highly reactive slabs.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 5

Persistent Slabs

An icon showing Persistent Slabs
Buried persistent weak layers have become reactive with heavy storm loading resulting in large avalanches.
Pay attention to overhead hazards like cornices.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Wet Slabs

An icon showing Wet Slabs
Continued rain at lower elevations may result in wet slab avalanches running to valley bottom. Loose wet avalanches are expected from steep terrain features.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Feb 8th, 2015 2:00PM