Avalog Join
Archived

Avalanche Forecast

Dec 11th, 2014–Dec 12th, 2014
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
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Purcells.

Although the trend shows improvement remember that the potential for triggering an avalanche is greatest at higher elevations due to recent heavy snowfall and strong winds.

Confidence

Fair - Due to the number of field observations

Weather Forecast

One last system is expected to cross the province tonight bringing moderate precipitation, high winds, and maintaining high freezing levels. We could see 5-10 cm by midday Friday. Freezing levels start near 2000 m but should drop to 1500 m late in the day. Winds are strong from the Southwest easing to light from the Northwest. The weekend looks much drier with a mix of sun and cloud. Freezing levels around 1000-1400 m on Saturday and 500-800 m on Sunday. Winds remain light.

Avalanche Summary

Reports from Wednesday include numerous loose wet slides up to size 2 from steep terrain below 2100 m throughout the region. There were also some new explosive triggered slabs up to size 2.5 from steep rocky terrain near Golden. One observer from the McMurdo Hut southwest of Golden reported seeing numerous avalanche crown lines and debris, particularly from alpine terrain.

Snowpack Summary

10-30 cm of moist or wet snow sits on a layer of surface hoar above 1800-2000 m. Below this the upper snowpack may be saturated. Another 15-20cm below this you may find a hard rain crust. In the Golden area this crust exists up to around 1600m, whereas in the south it is up to 2000m or higher. In total, last week's storm produced slabs up to 1m thick in the north of the region and around 60cm thick in the south. This slab sits on the mid-November weak layer (surface hoar, facets, and/or a crust). Below this you will likely find a 15-20cm thick layer of sugary facets, which is sitting on a solid rain crust from early November. The reactivity of these layers may be slowly diminishing, but they still warrant cautious consideration. Snowpack tests are getting hard pops and drops results, indicating the potential for large propagation and large avalanches.

Avalanche Problems

Persistent Slabs

Choose well supported terrain without convexities.>Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5

Loose Wet

The likelihood of loose wet slides should decrease as temperatures drop and precipitation eases off later on Friday. 
Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Storm Slabs

Storm and wind slabs continue to build, primarily above 1800-2000 m. Very strong winds may have created deep wind slabs well below ridge crests and cross-loaded gullies.
Be aware of conditions that change with elevation and use ridges or ribs to avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4