Archived

Avalanche Forecast

Apr 6th, 2015–Apr 7th, 2015

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Purcells.

Warmth is the primary driver of avalanche hazard and the weather forecast calls for a steadily increasing freezing level over the next few days. Minimize your exposure to large slopes if the snowpack is becoming moist or wet.

Confidence

Fair

Weather Forecast

TUESDAY: Freezing level starting at valley bottom, rising to 1800m. Light variable winds at all elevations. No significant precipitation expected. Few clouds in the morning, cloud cover increasing in the afternoon.WEDNESDAY: Freezing level starting at 1000m, rising to 2000m. Light N/NW winds at all elevations. No significant precipitation expected. Clear skies initially, cloud cover building in the afternoon.THURSDAY: Freezing level starting near 1500m, rising to around 2200m. Light W/SW winds at all elevations. Clear skies.

Avalanche Summary

Several cornice falls have been reported in the last few days, some of which have triggered avalanches on slopes below. On Wednesday, a rider triggered size 2 avalanche was reported that likely started on the March PWL before it stepped down to the ground.

Snowpack Summary

The recent 10 to 25cm of storm snow was shifted by variable strong winds into wind slabs on lee slopes above 2000m. These wind slabs are probably growing old and tired. Cornices are large and touchy in some spots. The new snow sits over a crust which is generally becoming more supportive. Low elevations sport an isothermal snowpack, which is now capped by a refrozen crust.Persistent weak layers in the upper snowpack remain a lingering concern, although they seem to be slowly gaining strength. In the north of the region, the mid-March crust/facet layer is down 40-60cm. The mid-February crust/facet/surface hoar layer, down about 80 cm, may also still be reactive in isolated areas. Weak layers which formed earlier in the winter are also a concern in certain spots.

Avalanche Problems

Cornices

Steadily increasing temperatures for the next few days will likely make cornices more prone to failure. You do not want to be on top of or underneath these large and dangerously heavy pieces of snow when they collapse.

When traveling in the alpine, be SURE you're on the ridge, and not on a cornice. These things demand your full attention.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Loose Wet

Anytime previously dry/cool snow experiences the intense kiss of the spring sun, loose wet avalanches are likely. Most south and west facing slopes are probably done, but keep this problem in mind as you piece together travel plans.

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: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2