Archived

Avalanche Forecast

Nov 23rd, 2016–Nov 24th, 2016

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

Below Threshold

The avalanche danger rating below treeline will be below threshold

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

Below Threshold

The avalanche danger rating below treeline will be below threshold

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

Below Threshold

The avalanche danger rating below treeline will be below threshold

Regions: South Columbia.

A two-day storm is expected to deliver moderate snowfall and winds to the region. Heightened avalanche danger will exist in the mountains during the storm.

Confidence

Low - Due to the number of field observations

Weather Forecast

Thursday: 10-15cm new snow expected with moderate winds from the southwest. Freezing level will sit near 1400m. Friday: 15-25cm of new snow expected with SW winds continuing and intensifying. Saturday will see some clearing with snowfall ending and cooler temperatures.

Avalanche Summary

Reports from Monday included a remotely-triggered, 20-40 cm thick, Size 2 wind slab avalanche on a SE facing alpine slope in Rogers Pass. Check the Glacier National Park Avalanche Forecast for more details. As of Wednesday, Nov 23rd, no new avalanche observations have been reported.

Snowpack Summary

Recent reports suggest snowpack depth is 100-190cm in the alpine and 80-140cm at treeline. The snowpack below treeline remains below threshold for avalanches, so early season hazards such as hidden rocks, stumps, and open creeks exist. Up to 50cm of recent storm snow is settling into a cohesive slab over a hard crust. Some reports suggest new snow is bonded well to this crust, however the potential exists for this layer to be triggered with heavier loads, including the forecast snowfall amounts. Southerly winds have formed wind slabs on lee features below ridgetops in exposed terrain. The mid and lower snowpack layers are mostly well-settled.

Avalanche Problems

Storm Slabs

Forecast new snow and wind will develop storm slab on steep slopes especially in exposed lee terrain.

Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3