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Archived

Avalanche Forecast

Jan 3rd, 2015–Jan 4th, 2015
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
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

Regions: Northwest Inland.

Winds will be the primary issue in the short term. Seek sheltered terrain and be aware of what is above you. 

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: A strong Pacific frontal system will impact the Coast beginning on Sunday morning. Expect moderate or locally heavy snowfall (10-15 cm) and strong SE ridge winds as the moist Pacific airmass battles with the Arctic front. Monday could be a bit drier before another frontal system arrives late in the day or overnight. This pulse should drop another 10-20 cm through Tuesday with moderate SW ridge winds. The freezing level remains at valley bottom with average treeline temperatures between -10 and -15.

Avalanche Summary

There are a couple recent reports of rider triggered wind slabs up to size 1.5 from steep treeline features. No new natural activity has been reported. Expect fresh wind and storm slabs to form as snow accumulates and winds increase this weekend.

Snowpack Summary

Recent winds have been highly variable with strong W-NW winds followed immediately by strong SE-NE winds. Hard and soft wind slabs should be expected on a variety of slopes in open terrain. rain was reported to almost 2000 m on New Years Day in the southern part of the region. Since then there's been around 15-20 cm of new snow. At higher elevations and northern sections there could be around 30-40 cm of recent storm snow. The new snow may be resting on older wind slabs or surface hoar in northern areas. Down 40-70 cm you may find another surface hoar layer, although it appears to be spotty in distribution. Near the bottom of the snowpack is a crust facet combo that was buried in mid-November. This layer is currently dormant and produces variable results in snowpack tests. I suspect it will remain sensitive to new inputs in the form of new snow and wind for the foreseeable future.

Avalanche Problems

Wind Slabs

New snow and strong winds will produce dense or hard wind slabs in exposed lee terrain and cross-loaded features. If we see more than 30 cm accumulate over the next few days then expect storm slabs to form in sheltered terrain.
Use ridges or ribs to avoid freshly wind loaded features. >Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Persistent Slabs

New loading from snowfall and strong winds could 'wake up' deeper persistent weaknesses and produce isolated very large avalanches. 
Use caution around convexities, ridge crests, rock outcroppings and anywhere else with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 1 - 6