Avalanche Forecast

Issued: Mar 18th, 2013 11:08AM

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

jlammers, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Wednesday

Weather Forecast

Tuesday: Mix of sun and cloud / Light to moderate southwest winds / Freezing level at 900mWednesday: Moderate to heavy snowfall / Strong to extreme southwest winds / Freezing level at 1300mThursday: Light snowfall / Light to moderate west winds / Freezing level at 800m

Avalanche Summary

A natural avalanche cycle to size 2.5 took place in response to new snow loading on Saturday night. With continued winds and up to 25cm of new snow on Sunday night I would expect continued wind slab activity at treeline and above.

Snowpack Summary

Generally moderate amounts of new snow fell on Saturday night and Sunday and have have been distributed by strong northerly winds into deeper windslabs in lee terrain. Depending on elevation, these recent accumulations may overlie a thick rain crust. Up to 1m below the surface is a layer surface hoar or a sun crust buried on March 10th. Natural avalanche activity has become less likely at this interface; however, human triggering is still possible. At lower elevations where last week's heavy rain saturated the snowpack, subsequent cooling has formed crusts and has dramatically strengthened the snow.Weaknesses deeper in the snowpack have become unlikely to trigger.Widespread cornice development has also taken place, and cornices are reported to be very large and weak.

Problems

Wind Slabs

New snow over the weekend and continued very strong winds have created new wind slabs. Watch for loading on a variety of aspects due to variable wind directions.

Be cautious as you transition into wind affected terrain.>Avoid travelling in areas that have been reverse loaded by winds.>Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

About 1m of snow overlies surface hoar or a sun crust buried on March 10th. Although triggering has become less likely, avalanches on this layer could be surprisingly large and destructive. Watch for increased reactivity with forecast sun on Tuesday.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 6

Loose Wet

Forecast sun on Tuesday may pack enough punch to trigger loose wet avalanches on sun-exposed slopes. Reactivity may be higher do to the presence of a crust which currently underlies loose dry snow.

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

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Mar 19th, 2013 2:00PM