Archived

Avalanche Forecast

Dec 25th, 2013–Dec 26th, 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

4: High

The avalanche danger rating below treeline will be high

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

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

Regions: Northwest Coastal.

Rising freezing levels will keep the avalanche danger high and will bring rain to the alpine in the south of the region.

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Synopsis: The next frontal wave with push onto the north coast early Thursday morning causing temperatures to spike before it shift southwards. Expect heavy precipitation to continue.Tonight and Thursday. Snow amounts: up to 20 cm overnight becoming heavy rain Thursday in the south, snow further north / Freezing levels: Rising to 2500m in the south, 1300m in the north / Ridge winds: Strong westerly. Friday: Snow amounts: Up to 10 cm / Ridge winds: Strong westerly / Freezing levels: 800m.Saturday: Snow amounts 10 to 20 / Ridge winds Light westerly / Freezing levels: 800m.

Avalanche Summary

No new observations. Numerous large- very large 2-3 natural slab avalanches occurred during the last storm and observed recently. Most seemed to be storm slabs and wet slabs, and glide crack releases.

Snowpack Summary

Freezing levels are going to be the thing to watch on Thursday.In the south were freezing levels are expected to climb as high as 2500m, rain will deliver a significant load to an already suspect upper snowpack. Further north continuing heavy snowfall and warming temperature will likely form widespread and reactive storm slabs.The December 22nd surface hoar is currently down 100cm in areas that did not avalanche during the last storm cycle.The mid pack features several persistent weak layers but these have likely gained strength at this point.In the north of the region a basal facet and crust combo lingers near the ground. It is most prevalent on NW - E facing aspects at the upper TL and alpine elevations.

Avalanche Problems

Storm Slabs

In the south: rising freezing levels will bring heavy rains to the alpine and may cause the new snow to react as a wet slab. In the north: continued loading by snow and wind will sustain a widespread storm snow avalanche cycle.

A very conservative approach is essential at this time.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely - Certain

Expected Size: 1 - 4

Persistent Slabs

Various buried weak layers are present in the region, especially in the North. New snow and wind may cause these weak layers to become more sensitive to triggering.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 3 - 6