Avalanche Forecast

Issued: Jan 14th, 2014 8:27AM

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.

bcorrigan, Avalanche Canada

Cariboos.

Summary

Confidence

Good - Freezing levels are uncertain on Friday

Weather Forecast

Synopsis: A strong ridge of high pressure will move into BC in the next few days raising temperatures and blocking precipitation. Small amounts of moisture may over spill the ridge initially allowing isolated flurries. Overnight: Trace of new snow, winds changing to moderate to strong from the W, freezing levels may rise to 900m.Wednesday: Light flurries, moderate to strong winds from the NW, freezing level to 1200m in parts of the forecast area.Thursday: No Precipitation in the forecast for Thursday, moderate to strong winds from the W. freezing levels to 1600mFriday: Sunny, no precipitations and freezing levels rising to 1600m. Light winds at ridge top.

Avalanche Summary

A widespread natural avalanche cycle has taken place in the past 24 to 48 hours as a result of the large amounts of new snow, rising temperatures and high winds. Numerous very large avalanches ( size 3's and 4's ) have been reported. Wind slabs and shallow snowpack areas are areas of high concern. The possibility of a relatively small to medium size avalanche stepping down to buried weak layers is high, and may produce a very large and destructive avalanche.

Snowpack Summary

Recent storm snow amounts up to 100cm now overly a variety of old snow surfaces, much of it transported by the strong winds into stiff wind slabs. Below this is soft facetted snow and/or surface hoar that was buried around Jan. 8th. There is also rain crust below the 1600m elevation band that should now be buried well over a metre, and another surface hoar or facet layer is down 160 + cm deep. Snowpack depths vary, but in general there is now 200 to 250cm of snow at tree line and as much as 300 cm in select places in the alpine. In some areas we're still dealing with a relatively thin snowpack (thanks to a windy early season and strong winds scouring slopes during the storm.). The basal facet/crust combo, ( weak sugary snow above and below a crust) near the ground was likely the reason so many large naturals were reported during and after this last storm cycle.

Problems

Storm Slabs

Operators have reported easy shears in the top 25 to 50 cm of storm snow. As well, the Jan 8th surface hoar,(now 80-100cm in some places below the surface), is still reactive in snow pack tests. Avoid riding large features and unsupported slopes.

The new snow will require several days to settle and stabilize.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid convexities or areas with a thin or variable snowpack.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Avoid slopes with glide cracks.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Persistent Slabs

A number of buried persistent weak layers in the mid and lower snowpack could become reactive with heavy loading from snow and wind this week. There is potential for large, full-depth avalanches.

The new snow will require several days to settle and stabilize.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid areas with overhead hazard.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 7

Valid until: Jan 15th, 2014 2:00PM