Archived

Avalanche Forecast

Mar 1st, 2017–Mar 2nd, 2017

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

Alpine

4: High

The avalanche danger rating in the alpine will be high

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

Alpine

4: High

The avalanche danger rating in the alpine will be high

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.

Strong to extreme winds and new snow are driving the danger ratings. Slab avalanches are primed for rider triggering.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

An organized low pressure system will track across the region bringing rising freezing levels, more snow and strong winds. Conditions will remain unsettled through the forecast period. Enhanced snow amounts may be greater than forecast for Saturday/ Sunday.Thursday: Cloudy with snow 5-10 cm. Ridgetop winds strong from the SW, alpine temperatures near -7 and freezing levels 1300 m.Friday: Periods of snow 5-15 cm. Ridgetop winds light gusting to 80 km/hr from the SW, alpine high of -5 and freezing levels 1400 m.Saturday: Snow 5-10 cm. Ridgetop winds generally light with strong gusts. Alpine temperatures high of -5 and freezing levels 1400 m.

Avalanche Summary

Several explosive triggered slab avalanches up to size 2.5 were reported on Wednesday.

Snowpack Summary

Another 20 cm of low density storm snow arrived overnight bringing the recent snow totals up to 50 cm since Saturday. Strong southwesterly winds will likely transport the new snow onto leeward slopes, building thicker and stiffer slabs. The new snow may have a poor bond to previous old snow surfaces that primarily consist of stiff wind slabs, crusts and facets. The mid-pack in this region is generally well settled and strong, but the bottom third of the snowpack is composed of weak facets (sugary snow crystals). Approximately 100-120 cm of settled snow sits above the weak layer of sugary, rotten facets that developed mid- December. This remains a concern and should be on your radar especially when change is happening to the snowpack.

Avalanche Problems

Storm Slabs

Touchy storm slabs may have a poor bond to old snow surfaces and be reactive to rider triggering. Thicker and stiffer slabs will exist on leeward slopes due to wind transported snow.

Recent wind loading have created wind slabs on leeward (northerly- easterly) slopes.Avoid avalanche terrain during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Deep Persistent Slabs

A weak layer near the base of the snowpack has the potential for large avalanches, especially in areas with minimal rider compaction or thin variable snow cover.

Avoid steep convexities or areas with a thin or variable snowpack.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4