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Avalanche Canada bcorrigan, Avalanche Canada

South Rockies Avalanche Forecast

Mar 20th, 2016 8:41AM

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

Warm temperatures will keep the danger rating high for the next few days. Give cornices a wide berth. Conservative terrain choices are essential until things cool down.

Summary

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

A pacific cold front will move into the region bringing cloudy skies and light amounts of precipitation. MONDAY: Cloudy, with the freezing level slowly descending from 2700m Sunday night to 2000m early Monday morning, then continuing its descent Monday evening to level off around 600m early Tuesday morning. Light south to southwest winds, scattered very light rain showers below 2000m. TUESDAY: Cloudy with flurries and/or light rain , freezing level is forecast to drop to 600 m overnight, then rise to 1600 m during the day. Winds are forecast to be light from the south to south west. WEDNESDAY: Cloudy with very light precipitation possible in the late afternoon, winds forecast to be light from the south. No overnight recovery on on Wednesday night, with the freezing level hovering around 1600 m.

Avalanche Summary

Reports from yesterday speak of storm slab activity on NE terrain as well as 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

Earlier in the week, 15 to 25 cm of new snow fell with light northwest winds. Recent winds from the South west have redistributed the storm snow onto high NE aspects. These wind slabs may be sitting on the mid-March crust, still being found 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 2300 m, after which they begin to disappear. There 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
South west winds have created reactive wind slabs on north east ( lee ) features
The new snow will require several days to settle and stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Cornices

An icon showing Cornices

Likelihood

Likely - Possible

Expected Size

2 - 4
Cornices are now quite large in the region and may be sensitive to loading by a rider or machine
Do not travel on slopes that are exposed to cornices overhead.>Stay well to the windward side of corniced ridges.>

Aspects:

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

Elevations:

Alpine, Treeline.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely

Expected Size

1 - 2
Steep south facing slopes may still warm up and produce loose wet avalanches
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Mar 21st, 2016 2:00PM