Archived

Avalanche Forecast

Mar 1st, 2013–Mar 2nd, 2013

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Coast.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Friday night: Ongoing precipitation. Strong SW winds. Freezing level around 1800 m.Saturday: Light precipitation. Moderate SW winds. Freezing level around 1500 m.Sunday: No snow expected. Light winds. Freezing level around 900 m.Monday: Light snow. Light winds. Freezing level around 1100 m.

Avalanche Summary

Initial reports from Friday suggest a widespread natural avalanche cycle to size 3.5.Almost every day this week, skiers have triggered slabs to size 2, failing on buried surface hoar/crusts which exist at all elevations and on all aspects. Some were triggered remotely, and they exhibited wide propagation. Details of some of these incidents can be found here. A natural cycle to size 2.5 occurred on Sunday night and Monday in response to new snow and wind-loading. A natural avalanche cycle is expected over the next few days in response to intense storm loading.

Snowpack Summary

Two very touchy weaknesses of surface hoar and/or a crust within the upper snowpack have already been responsible for a number of avalanche incidents. Add an intense storm, with heavy precipitation rates, warming and very strong winds, and we have a good recipe for widespread avalanche activity. The lower snowpack is well settled.

Avalanche Problems

Storm Slabs

Storm snow is expected to become very touchy with continuous loading throughout the forecast period, especially where wind-loaded. At lower elevations, rain-weakened snow is causing loose wet avalanche conditions.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Persistent Slabs

Persistent weaknesses buried last week are extremely touchy, can be triggered from a distance, and may create surprisingly large avalanches.

Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 3 - 7