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Avalanche Forecast

Jan 29th, 2021–Jan 30th, 2021
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
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
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

Regions: South Rockies.

The recent storm snow will be redistributed by moderate to strong southwest wind throughout the day and build fresh wind slabs in lee terrain features in the alpine and at exposed treeline.

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

FRIDAY NIGHT: Cloudy with clear periods, trace to 1 cm new snow, light to moderate southwest wind, treeline temperature -10 C.

SATURDAY: Mainly cloudy, trace to 3 cm new snow, moderate to strong southwest wind, treeline temperature -9 C.

SUNDAY: Mainly cloudy, 5 cm new snow and 15 cm in the west of the region, moderate to strong southerly wind, treeline temperature -6 C.

MONDAY: Mainly cloudy, 10 cm new snow and 20 cm in the west of the region, moderate to strong southwest wind, treeline temperature -4 C.

Avalanche Summary

Several small loose dry avalanches (sluffs) in steep alpine and treeline terrain were reported over the last few days. Small wind slab avalanches were triggered by skiers on Wednesday. 

Snowpack Summary

10-20 cm of recent snow buried surface hoar and old surfaces. On steep solar aspects the recent snow sits on a sun crust. In the alpine and upper treeline, the new snow buried heavily wind affected surfaces from last week's strong to extreme southwest winds with scouring, sastrugi, isolated pockets of soft snow and layers of hard wind slab. A hard thick crust is found up to 1900 m. 

A solid mid-pack sits above deeply buried decomposing crust and facet layers near the bottom of the snowpack (100-150 cm deep). Avalanche activity on these layers has been sporadic and mostly triggered by large loads such as wind slab avalanches and cornice falls. Though unreactive under the current conditions, steep rocky slopes and shallow snowpacks should still be carefully assessed and approached with caution.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Avalanche Problems

Wind Slabs

Moderate to strong southwest wind will redistribute loose snow and build fresh wind slabs in lee terrain features in the alpine and at exposed treeline. These slabs will be particularly reactive where they overlie surface hoar.

Cornices might grow larger and more fragile.  

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2