Avalanche Forecast

Issued: Apr 21st, 2013 10:43AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Cornices, Loose Wet and Persistent Slabs.

swerner, Avalanche Canada

Cariboos.

The Public Avalanche Forecasts will come to an end on Monday. Starting Tuesday you can find spring messaging under the "Forecast Details" tab below.See you next season!

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

An upper ridge stalls off the coast bringing sunny skies and dry cool conditions through Tuesday. By mid-week freezing levels will rise to 2000 m.Monday: Mostly sunny skies. Ridgetop winds will blow light from the NW and freezing levels will rise to 1800 m. Tuesday: Broken cloud cover and a chance of flurries. Ridgetop winds moderate from the NW and freezing levels 1800 m. Wednesday: The stationary ridge of high pressure continues bringing sunny skies and freezing levels up to 2000 m. Ridgetop winds will blow light from the SW.

Avalanche Summary

On Saturday a size 2.5 cornice fall occurred and did not trigger a slab on the slope below. With rising freezing levels and sunny skies conditions can change quickly and avalanche danger will rise.

Snowpack Summary

Up to 15 cm of new snow sits on a variety of old surfaces and generally seems to be bonding. Wind slabs have built on lee slopes and behind terrain features. Cornices are huge and remain a concern, especially with daytime warming which will weaken them. Surface snow will likely become wet and deteriorate on solar aspects.Buried 60-100 cm down, exists an interface of crusts and buried surface hoar. This is mainly found at upper elevations on all aspects. It seems to be gaining strength but I would remain suspicious, especially of large, steep high-alpine slopes. Dig down, and test layer of concern.

Problems

Cornices

Large, looming cornices exist on ridgelines and will likely become weak with daytime warming. They threaten slopes below. Keep your distance from them. New snow and moderate winds have built wind slabs on lee slopes and behind terrain features.

Use ridges or ribs to avoid pockets of wind loaded snow.>Pay attention to overhead hazards like cornices and stay well back on ridgelines.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Loose Wet

Loose wet avalanche activity is likely with rising freezing levels and clear sunny skies. Conditions can change quickly with timing, aspect and elevation.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

A weak interface is buried about a metre down. A smaller avalanche stepping down, cornice fall, the weight under a snowmobile, or the weight of a person from a thin-spot trigger point could trigger a large and destructive avalanche.

Conditions are greatly improved, but be mindful that deep instabilities are still present.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

2 - 6

Valid until: Apr 22nd, 2013 2:00PM