Avalanche Forecast

Issued: Mar 24th, 2013 10:15AM

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

swerner, Avalanche Canada

South Rockies.

Summary

Confidence

Fair

Weather Forecast

A fairly benign, spring-like weather pattern has set up through the forecast period. Monday: A surface ridge will remain as a weak warm front moves through the western parts of the region. Skies will be sunny with high scattered cloud and no significant precipitation. Ridgetop winds will be light from the W-NW and high diurnal temperature swings will persist. Alpine temperatures will remain near -5.0. Tuesday/Wednesday: No significant changes in the weather pattern. Mostly sunny skies with a bit more cloud cover on Wednesday. Freezing levels will hover around 2000 m Tuesday afternoon through Wednesday as a warmer air mass sits over the region. Ridgetop winds will stay light from the West.

Avalanche Summary

No new natural slab avalanche activity. Loose dry sluffing was noted from steep North facing terrain up to size 1.0.

Snowpack Summary

Approximately 40-70 cm of recent settling storm snow sits on top of a buried rain crust approximately down 50 cm and exists up to around 2100 m. In areas near Sparwood, the new snow initially bonded poorly to this crust, and a few large avalanches were observed that likely released on this layer. In the North Elk Valley, the bond at the crust was reported to be fairly good. Generally, this interface has now become stronger for all parts of the region. However, a large trigger such as a cornice fall or a skier or sledder hitting the sweet spot, could potentially trigger a large avalanche on this layer in steep terrain. Recent wind slabs exist in the immediate lee of ridge lines and terrain features. Cornices are large and fragile. Mid and lower snowpack layers are generally well-settled.

Problems

Cornices

Large looming cornices exist on most ridgelines. Cornices may become weak under the influence of the sun. They are a hazard in themselves and they could trigger slopes below.

Give cornices a wide berth when travelling on or below ridges.>Cornices become weak with daytime heating, and solar radiation so travel early on exposed slopes.>

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 5

Wind Slabs

Wind loaded and cross-loaded slopes can still be found at treeline and alpine elevations. There is still a chance a small wind slab avalanche could step down to the March 16th rain crust.

Avoid open steep slopes with convexities or a thin variable snowpack.>Be cautious as you transition into wind affected terrain.>Watch cross loaded slopes at or above treeline.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Loose Wet

Clear sunny skies and warmer afternoon temperatures may promote deterioration within the upper snowpack. If surface snow becomes moist or wet, loose wet avalanches may occur. Watch solar aspects.

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

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Mar 25th, 2013 2:00PM