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Avalanche Forecast

Jan 3rd, 2018–Jan 4th, 2018
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
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
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

Regions: South Rockies.

Expect to continue to see persistent slab avalanche activity as the snow sitting above the persistent weak layer further settles and consolidates with forecast warmer temperatures.

Confidence

Moderate - Freezing levels are uncertain on Thursday

Weather Forecast

THURSDAY: Mainly cloudy / light west wind / Alpine temperature 0 with a temperature inversion  FRIDAY: Cloudy with sunny breaks / Light west wind / Alpine temperature -2 SATURDAY: Mainly cloudy / Light to moderate west wind / Alpine temperature -2

Avalanche Summary

Continued avalanche activity was observed in steep low elevation terrain (road cut banks) in the Elk Valley on Wednesday to size 1.5. These were triggering very easily. On Monday, a machine triggered Size 1.5 persistent slab avalanche was reported running on the mid December surface hoar layer, down 35 cm at that location (1700m). See the details here in the MIN post. On Sunday a Size 2 persistent slab (stepping down to late November crust/facets) was intentionally triggered on an east aspect near 2000m in the south of the region.On Saturday several natural and human triggered storm slab avalanches to Size 2 were reported on a wide variety of aspects and elevations. Furthermore, several persistent slab avalanches to Size 1.5 were reported (with some remote-triggered by skiers).

Snowpack Summary

Up to 45 cm of snow fell on at the end of last week. Since then, strong winds from a wide range of directions have blown snow around: In the south of the region winds were from the south west; whereas in the north the winds were from the north east. The main question in the snowpack surrounds the mid-December layer sitting beneath the recent snow. This layer includes crusts on solar aspects and feathery surface hoar in sheltered terrain at and below treeline, and has consistently shown its reactivity, even on small features below treeline. The lower snowpack is composed of mostly soft sugary snow and a few early season crusts that have not produced significant test results recently.

Avalanche Problems

Persistent Slabs

A weak layer composed of surface hoar and/or crusts is buried 35-70 cm below the surface. This layer continues to be very reactive to human triggers and may not improve anytime soon.
Choose well supported terrain without convexities.Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.Watch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Wind Slabs

Moderate winds have created fresh wind slabs at higher elevations. In the south of the region, the winds were from the south-west. In the north of the region the winds were from the north east.
If triggered, the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2