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Avalanche Canada bcorrigan, Avalanche Canada

South Rockies Avalanche Forecast

Mar 21st, 2016 9:26AM

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

Warm temperatures will keep the danger rating elevated for the next few days.  Conservative terrain choices are essential until things cool down.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

A series of Pacific frontal systems will pass through the area in the next 4 days bringing cloudy skies and  small amounts of precipitation. TONIGHT:  No precipitation in the forecast, freezing level dropping to 600m. TUESDAY: Cloudy with light precipitation, freezing level climbing to 1800m during the day, then dropping to valley bottom overnight, winds will be light, south to south west. WEDNESDAY: Light precipitation in the late afternoon, winds forecast to be light from the south, freezing level climbing to 1800 m during the day and hovering around 1600m overnight.  THURSDAY:  10mm of precipitation in the forecast with the freezing level staying close to1600m before descending to valley bottom Thursday night.  Precipitation forecast are uncertain for Thursday as a closed low pressure system moves into the area. 10 to 15 cm of snow accumulation possible above1200m, winds are forecast to be light to moderate at ridge tops from the west.

Avalanche Summary

Reports from yesterday are mostly of loose wet releases running in steep terrain on South aspects. Cornices are reported to be touchy and sensitive to triggering. Over the course of the last week we have received many reports of cornice failure with some of them being quite large.

Snowpack Summary

Recent south west winds have redistributed the last storm snow onto high NE aspects. These wind slabs may be sitting on the mid-March crust, around 20 cm below the snow surface. An earlier March crust can be found down at 50 cm below the surface. Both of these crusts are reported to be present from valley bottom to around 2300m, after which they begin to disappear. No recent avalanche activity has been reported on these crusts. South and East aspects are becoming moist with daytime heating and solar warming, then re-freezing overnight. North aspects are reported to be dry above 1700m.  Of note are thin snowpack areas in the South Rockies region where deeply buried weak layers near the ground remain sensitive to triggering. Huge cornices still hang over many ridge-lines and with solar radiation and warming temperatures, may now be quite reactive.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely - Possible

Expected Size

1 - 3
Now confined to high elevation north east aspects above 1800m.
Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>The new snow will require several days to settle and stabilize.>

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Cornices

An icon showing Cornices

Likelihood

Likely - Possible

Expected Size

2 - 4
Cornice failures produce enormous loads on the slopes below, potentially triggering deeply buried week layers.
Stay well to the windward side of corniced ridges.>Do not travel on slopes that are exposed to cornices overhead.>

Aspects:

North, North East, East, South East, South.

Elevations:

Alpine, Treeline.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely

Expected Size

1 - 2
A loose-wet surface slide could easily push a rider into a dangerous situation.
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, South West.

Elevations:

All elevations.

Valid until: Mar 22nd, 2016 2:00PM