Avalanche Forecast

Issued: Mar 30th, 2013 9:54AM

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

swerner, Avalanche Canada

South Columbia.

Danger could INCREASE TO CONSIDERABLE with intense radiation on south and west aspects, especially at treeline and below. Be aware of how the warm weather is changing the snowpack.

Summary

Confidence

Good

Weather Forecast

Same story, sunglasses and sunscreen required. A dominating high pressure system with sunny skies, rising freezing levels and light winds continues through to Monday. The pattern will start to deteriorate by Tuesday, showing increased cloud and grey skies with no precipitation. Sunday: Few to scattered high cloud. Alpine temperatures 5.0 and freezing levels 2500 m. Ridgetop winds light from the NW.Monday: Scattered clouds. Alpine temperatures 6.0 and freezing levels rising to 2600 m. Ridgetop winds blowing light from the NW.Tuesday: Cloudy. Alpine temperatures -1.0 and freezing levels falling to 2300 m. Ridgetop winds blowing light from the SW.

Avalanche Summary

Solar aspects have been very active showing loads of natural loose wet avalanches and cornice releases up to size 2.5. I expect natural avalanche activity to continue with freezing levels to the moon and sunny skies throughout the forecast period.

Snowpack Summary

Surface faceting and surface hoar growth ( up to 20 mm) has been prevalent on shady slopes and at upper elevations, while the surface snow on sun-exposed slopes and at lower elevations has been subject to daily melt-freeze cycles. Cornices are large and weak. Surface hoar buried March 10th is down more than a metre in most places. This layer seems to be bonding in most places and is a low probability - high consequence problem. If triggered, it would probably require a very large load (cornice fall) or hitting the sweet spot in thin, variable snowpack areas.

Problems

Cornices

Cornice falls are a concern during warming. Slopes with corniced entrances, or exposed to cornice falls should be avoided. It is possible that the weight of a cornice dropping onto the slope below could trigger an avalanche on the Mid-March crust.

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

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Likely

Expected Size

2 - 6

Loose Wet

Warm temperatures and strong solar radiation may cause loose moist or wet snow avalanches. Keep an eye on changing conditions: Avalanche activity, snowballing, moist and wet snow are initial indicators of deterioration and increased hazard.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Valid until: Mar 31st, 2013 2:00PM