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Avalanche Forecast

Jan 10th, 2014–Jan 11th, 2014
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
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
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
1: Low
The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

Confidence

Good

Weather Forecast

Overnight and Saturday: Heavy snowfall occurring overnight and throughout Saturday / Moderate southwest wind (with extreme gusts) / Freezing level at 1100mSunday: Light snowfall / Moderate to extreme west winds / Freezing level at valley bottom rising to 1300mMonday: Light snowfall / Moderate to extreme southwest winds / Freezing level at 1300m

Avalanche Summary

On Thursday, numerous wind slab avalanches to size 1.5 were observed in alpine terrain. A size 2 deep persistent slab avalanche was reported on Blackcomb on Wednesday. This slide was accidentally triggered by a snow cat and failed on a weak facetted layer near the ground. Check out Waynn Flann's avalanche blog for photos and more information. This avalanche highlights the potential for large and deep avalanches in many areas on the South Coast. Heavy loading Friday night and Saturday will most likely trigger full depth avalanches in some places.

Snowpack Summary

Around 15-30 cm of new snow has fallen in the last few days and may overlie surface hoar in sheltered terrain. Ongoing moderate to strong southwest winds have formed touchy wind slabs in exposed lee terrain and cross-loaded features. The cold temperatures from early December have left weak faceted crystals that seem to be variably reactive. In higher elevation terrain where the snowpack was deeper, the facets likely co-exist with a crust in the mid pack. In lower elevation terrain or in shallow, rocky areas of the alpine, the facets are most likely more widespread and may exist down near the ground. Either way, the "wait 48 hours and you're good" Coastal mantra does not apply as these conditions are likely to persist for some time, and will probably become reactive with forecast snowfall.Early season riding hazards such as rocks, stumps and logs are lurking below the surface in many areas. In glaciated terrain open and poorly bridged crevasses are everywhere.

Avalanche Problems

Storm Slabs

Heavy snowfall and intense winds will create potent storm slabs at all elevations. Make conservative terrain choices.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid areas with overhead hazard.>It is a good time to stay within the boundaries of a ski resort.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 5

Persistent Slabs

Saturday's storm loading will be the first big "shock" for weak sugar snow which formed during December's cold snap. Where this weakness exists, there is potential for very large and destructive avalanches.
Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 5