Archived

Avalanche Forecast

Dec 13th, 2018–Dec 14th, 2018

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

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

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Rockies.

Warming on Friday may have an adverse effect on snow stability, particularly on slopes that face the sun.

Confidence

Moderate - Freezing levels are uncertain on Friday

Weather Forecast

THURSDAY NIGHT: Light snow, 2 cm or so.FRIDAY: Sunny. Strong southwesterly winds. Freezing level around 1800 m. Light snow Friday night.SATURDAY: A mix of sun and cloud. Winds becoming light to moderate southwesterly. Freezing level around 900 m.SUNDAY: Flurries. Freezing level rising to around 1800 m. Moderate or strong southwesterly winds.

Avalanche Summary

No new avalanches have been reported in the region, but rugged travel conditions at lower elevations have lately been discouraging travel in the alpine, where the bulk of our current avalanche danger resides.

Snowpack Summary

About 20-25 cm of new snow has buried previous snow surfaces that ranged from soft power to hard wind slab and sun crust. Strong winds have likely been aggressively forming storm slabs and wind slabs with the new snow at higher elevations.Beneath the new snow and old surface, the snowpack has a thin, weak structure, with the bottom half of the snowpack composed of weak facets and crusts. This basal layer has not been active, but terrain features like smooth alpine bowls with variable snowpack depths are still suspect given this snowpack structure. Currently only 30-90 cm of snow can be found in alpine areas and much less at lower elevations

Avalanche Problems

Wind Slabs

Recent strong winds and new snow have set up wind slabs in many exposed alpine and treeline areas. Warming on Friday could have a destabilizing effect on these slabs.

Be alert to conditions that change with elevation, aspect and exposure to wind.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The weak snow in the lower snowpack could produce large avalanches. Be cautions in areas where the surface snow has formed a cohesive slab, such as around thick wind deposits.

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.Be especially cautious as you transition into wind affected terrain.Back off if you encounter signs of instability like whumphing, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2