South Columbia

Stormy weather will continue to create very dangerous avalanche conditions.

Avoid avalanche terrain during periods of heavy loading from new snow or wind.

High

• We are confident a natural avalanche cycle will begin shortly after the arrival of the incoming weather.
• We are confident that there are persistent slabs in the snowpack, but uncertain about how likely they are to trigger.

Poor visibility restricted field observationson Wednesday. On Tuesday, evidence of a natural cycle was observed with numerous natural storm slabs and very large persistent slabs (size 1.5 to 3), some running full path.

Human-triggered persistent slabs keep being reported, with some being triggered accidentally or remotely (from a distance), were reported on all aspects and elevations.

A natural avalanche cycle is likely with the incoming weather.

Daily light snowfall is bringing the totals to 25 to 50 cm of recent snow since Monday, combined with moderate to strong westerly wind.

Three persistent weak layers of concern may be found in the upper 150 cm of the snowpack:

• 45 to 60+ cm down is a layer of surface hoar in sheltered areas, or a melt-freeze crust on sun-exposed slopes from mid-February.

• 60 to 100+ cm down is the early-February layer of surface hoar in wind-sheltered terrain and a crust on sun-exposed slopes.

• 80 to 120 cm down is the late-January layer of surface hoar and facets over a melt-freeze crust.

All of these persistent layers have continued to produce large avalanches in the region.

The remainder of the snowpack below is well consolidated.

Wednesday Night

Cloudy. 10 to 25 cm of snow. 60 km/h soutwest ridgetop wind. Treeline temperature -7 °C.

Thursday

Cloudy. 10 to 20 cm of snow. 60 km/h southwest ridgetop wind. Treeline temperature -6 °C. Freezing level 1500 m.

Friday

Cloudy. 15 to 20 cm of snow. 50 km/h west ridgetop wind. Treeline temperature -6 °C.

Saturday

A mix of sun and clouds. 40 km/h west ridgetop wind. Treeline temperature -7 °C.

More details can be found in the Mountain Weather Forecast.

• Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
• Avoid avalanche terrain during periods of heavy loading from new snow, wind, or rain.
• Any travel under High danger should exclusively be in flat or gentle terrain, far away from any overhead hazard.
• Be aware of the potential for larger than expected storm slabs due to buried surface hoar.