Avalanche Forecast

Issued: Mar 25th, 2013 10:21AM

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

Good

Weather Forecast

A dominating ridge of high pressure will continue over the Interior through the forecast period. Spring-like conditions will remain the theme, with gradual warming Wednesday/Thursday. Tuesday: Mainly clear skies with possible mid-high cloud cover. Freezing levels 2000 m in the afternoon, and then falling back to valley bottom overnight. Ridgetop winds blowing light from the NW.Wednesday: Scattered high cloud with alpine temperatures -1.0. Freezing levels 2200 m, and then falling to 1000 m overnight. Ridgetop winds light from the SE.Thursday: Mostly clear and sunny. Freezing levels 2200 m and then falling to 1400 m overnight. Ridgetop winds will blow light from the SW.

Avalanche Summary

No new natural avalanche activity.

Snowpack Summary

Approximately 40-70 cm of recent settling storm snow sits on top of a buried rain crust 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/sledder hitting the sweet spot, could potentially trigger a large avalanche on this layer. Recent wind slabs exist in the immediate lee of ridge lines and terrain features. Cornices are large and will likely become weak due to strong solar radiation and warming temperatures. Surface snow may become moist or wet up to 2200 m, especially on solar aspects. Melt-freeze conditions may exist.

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.

Cornices become weak with daytime heating, give them a wide berth.>Avoid steep slopes below cornices.>

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

Elevations: Alpine, Treeline.

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.

Whumpfing is direct evidence of a buried instability.>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 are likely. 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: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Mar 26th, 2013 2:00PM