Archived

Avalanche Forecast

Mar 28th, 2014–Mar 29th, 2014

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

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

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Coast.

Forecast snow amounts are uncertain. If snow amounts at treeline exceed 20cm, the danger will likely be high there too.

Confidence

Poor - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A broad upper level trough settles in over the Southern Coast which should generate significant precipitation through the weekend.Saturday: Freezing Level: 600m rising to 1300 - 1500m Precipitation: 5-15mm | 5 - 20cm; Treeline Wind: Light, South | Ridgetop Wind: Strong, SouthSunday: Freezing Level: 500m rising to 1200 - 1500m Precipitation: 2-5mm | 2-10cm; Treeline Wind: Moderate, SW | Ridgetop Wind: Strong, SWMonday: Freezing Level: 400m rising to 1400 - 1800m; Precipitation: Trace; Treeline Wind: Light, SE | Ridgetop Wind: Light, SE

Avalanche Summary

Avalanche activity on Thursday was limited to point releases out of steep solar terrain. These loose snow avalanches ran to size 1.5, involving the upper 20 cm of the snowpack.

Snowpack Summary

There may be some areas where the recent snow does not bond well to melt-freeze crusts on solar aspects. The forecast new storm should add a new load above these weak bonds and may be sensitive to triggering from light additional loads like skiers or riders. The persistent weak layers from early March and early February continue to be a concern. The March weak layer of wind-scoured crusts, melt-freeze crusts, and/or surface hoar is reported to be down 70-80 cm. The February crust/facet/surface hoar layer is now deeply buried down 150-250 cm and may still be triggered by heavy loads like cornice falls or storm slab avalanches in motion. Long fracture propagations resulting in very large avalanches are possible with this layer. Avalanches releasing on these layers may step down to the ground during periods of strong solar radiation or warm spring rain.

Avalanche Problems

Storm Slabs

New snow and wind should create fresh slabs that increase in sensitivity to triggering as the day goes on. Slopes immediately lee of ridge crest will likely be the most problematic. The new load may activate the old storm interface too.

Use ridges or ribs to avoid pockets of wind loaded snow.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4

Deep Persistent Slabs

The recent snow has added a new load above the deeply buried weak layers. Cornice falls or storm slab avalanches in motion may trigger the persistent weak layers resulting in very large avalanches.

Give cornices a wide berth when travelling on or below ridges.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6