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Archived

Avalanche Forecast

Jan 23rd, 2016–Jan 24th, 2016
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
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
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

Regions: Northwest Coastal.

A Special Public Avalanche Warning continues for this region. Conservative route selection and cautious decision-making is required.

Confidence

High

Weather Forecast

Sunday: Mainly cloudy with light snow. The freezing level is around 400 m and winds are moderate from the southeast. Monday: Periods of snow – 10-15 cm. The freezing level rises to 800-1200 m and winds increase to strong from the S-SW. Tuesday: Periods of snow. The freezing level is around 1000-1500 m. Winds remain moderate or strong from the SW.

Avalanche Summary

Observed avalanche activity varies throughout the region. Some reporters observed a fairly widespread avalanche cycle with numerous slabs up to size 2.5, mainly from slopes at and below treeline. Others reported only a couple natural slab avalanches up to size 2 from wind-loaded features. On Friday, there was one report of a size 3.5 slab that was remotely triggered by a helicopter touching down. Variable avalanche activity highlights the current challenges with buried and touchy persistent weaknesses.

Snowpack Summary

Light snowfall and steady moderate S-SE winds continue. Expect fresh wind slabs overlying older wind-affected surfaces in exposed lee and cross-loaded terrain. The January 9th surface hoar/facet layer down 50-70 cm in most places, and seems most concerning at and below treeline. Approximately 10 cm below this weakness you might find the Dec. 26/31 surface hoar layer. Reports of remote triggering, whumpfing, and sudden "pops" shears are all indications that both these layers could propagate well if triggered. Deeper persistent weaknesses buried in December have the potential to wake-up to heavy loading, rapid warming, or avalanches stepping-down.

Avalanche Problems

Persistent Slabs

Buried surface hoar, now 60 cm deep on average, is primed for triggering. It's possible for light loads to trigger slabs even from relatively low angle slopes. Be extra cautious near treeline where surface hoar is more likely to be preserved. 
Be careful with low angle slopes that may not normally be a concern.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 5

Storm Slabs

Storm and wind slabs continue to grow. These slabs may be particularly touchy in exposed lee (W-NE) and cross-loaded terrain. 
Choose well supported terrain without convexities.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4