Avalanche Forecast

Issued: Apr 21st, 2013 10:51AM

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

swerner, Avalanche Canada

South Coast.

The Public Avalanche Forecasts will come to an end on Tuesday. General spring messaging will be found 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 cooler conditions through Tuesday. By mid-week freezing levels will gradually start to rise near 2000 m.Monday: Mostly clear skies. Ridgetop winds light from the North and freezing levels reaching 1900 m. Tuesday: Mix of sun and cloud. Possible light pulses of precipitation. Ridgetop winds light from the North and freezing levels 1800 m. Wednesday: The stationary ridge of high pressure continues bringing sunny skies freezing levels up to 2300 m. Ridgetop winds will blow light from the West.

Avalanche Summary

No recent avalanche activity has been reported.Throughout the past week, numerous rider triggered and isolated remote/sympathetic events have been reported in high (2300-2700m) north and northeast facing slopes up to size 2.5, all associated with preserved surface hoar. Much of the reported activity has reacted on buried surface hoar, and seems to be occurring in the north of the region in the Duffey Lake/ Birkenhead areas, through the Hurley and up towards Bralorne/Goldbridge.

Snowpack Summary

Up to 30 cm of new snow fell Saturday. Wind slabs likely exist on lee terrain. At lower elevations, spring temperatures have created isothermal snowpack conditions.About 40-90 cm below the surface lies the April 5th interface. On solar aspects, the layer is a strong melt-freeze crust, with some faceting observed above and below. On Northwest to Northeast aspects above about 2300m, this interface may be preserved surface hoar (up to 15mm). Where the surface hoar is present we have reports of sudden results in stability tests and have seen rider triggered, sympathetic and remote events up to size 2.5. Although this interface may be gaining some strength, continued reactivity is expected with the potential for large avalanches.Cornices are huge and will continue to grow with the forecasted precipitation.

Problems

Persistent Slabs

The April 5th interface lingers as a persistent problem, especially in the north of the region. Touchy surface hoar continues to be reactive on high, north-facing slopes.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Dig down to find and test weak layers before committing to a line.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Wind Slabs

Up to 30 cm of new snow has fallen in the Coquihalla, and on the East side of the Duffy. New wind slabs have likely built on lee slopes and may be touchy to rider triggers.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

Loose wet avalanche activity will be likely under the influence of the sun and rising freezing levels.

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

Possible - Likely

Expected Size

1 - 4

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