Archived

Avalanche Forecast

Nov 19th, 2013–Nov 20th, 2013

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

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

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: Glacier.

A widespread avalanche cycle is ongoing, with large avalanches running to the end of their runouts. Areas exposed to overhead terrain, such as traveling up towards Balu Pass, are not recommended. Minimize your exposure and use safe travel practices.

Weather Forecast

Snowfall rates should off today, but windloading will continue with moderate to strong W'ly winds. There should be clearing later today, with alpine temps of -4. Wed and thursday should be dry with a mix of sun and cloud, temps of -15 to -20 and moderate to strong winds shifting to the NW.

Snowpack Summary

Hourly snowfall rates of up to 4cm an hour overnight, magnified by SW winds transporting snow, rapidly loaded the snowpack. Snowpack tests yesterday found several reactive storm snow instabilities. The Nov 12 surface hoar layer, now down ~1m, gave sudden planar results on a SE aspect at 2050m. All reports from the field indicated slabby conditions.

Avalanche Summary

A widespread natural avalanche cycle started overnight with heavy snowfall and moderate to strong winds. Numerous size 2.5-3 avalanches occurred in paths along the highway east and west of Rogers Pass. Most notably, Laurie, Junction E, and Crossover slidepaths had size 3 avalanches running into the avalanche fans with some to the end of the runout.

Confidence

Avalanche Problems

Storm Slabs

60cm of snow in 48hours, with strong winds, have formed a reactive storm slab. Large avalanches have been observed from all aspects, running well into the alder. This will continue with ongoing loading by wind and snowfall.

Choose regroup spots carefully.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 3

Wind Slabs

A widespread avalanche cycle is occurring due to rapid loading by snowfall and windloading. Expect reactive windslabs on exposed slopes.

Avoid avalanche terrain during periods of heavy loading from new snow and wind.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 3