Archived

Avalanche Forecast

Feb 7th, 2020–Feb 10th, 2020

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

2: Moderate

The avalanche danger rating below treeline will be moderate

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

1: Low

The avalanche danger rating below treeline will be low

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: North Rockies.

A break in the storm is welcome and will probably reduce the likelihood of avalanches. The factor that could change that is the sun - best avoid steep sunny slopes if the sun feels hot.

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Friday night: Flurries. Moderate northeasterly winds. Treeline temperatures around -10C.

Saturday: Dry with sunny periods. Light northwesterly winds increasing to moderate in the afternoon. Daytime high temperatures around -7C.

Sunday: Flurries. Strong to extreme northwesterly winds. Daytime high temperatures around -7C.

Monday: Flurries. Strong westerly winds. Daytime high temperatures around -3C.

Avalanche Summary

A skier triggered a size 1.5 wind slab avalanche on a northwest aspect at around 1750 m on Thursday. Also on Thursday, several storm slab avalanches up to size 2.5 were triggered on northerly aspects.

We are aware of an avalanche that occurred Sunday Feb 2 in the Upper Burnt area that is presumed to involve a snowmobiler. Preliminary information indicates that avalanche was a size 2.5 on a southeast aspect at 1600 m with a fracture line depth of 130 cm.

Snowpack Summary

Approximately 30-60 cm recent storm snow sits above a thin rain crust from the warm, wet storm on Feb 01. This rain crust has been reported to exist up to treeline elevations around 1700 m. Initially this layer was described as reactive and was the focus of a number of avalanches. However, it now appears to be gaining strength and probably won't end up being a significant long-term weak layer.

In the mid-pack there may still be a layer of surface hoar buried in late December. It's gaining strength, but should remain a concern since snowpack tests still demonstrate this layer has the potential to slide, albeit in isolated areas and/or with very large triggers.

Terrain and Travel

Expect slab conditions to change drastically as you move into wind exposed terrain.
Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.

Avalanche Problems

Wind Slabs

Previous winds were from from the southwest. More recent winds are blowing from the northwest. Expect wind slabs to have formed on a variety of aspects in exposed locations.

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

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Cornices

Cornices have been reported to be especially large. Cornice collapses become likely in warmer temperatures and/or when the sun is out. The weight of a large cornice dropping could be sufficient to trigger a large avalanche on the slope below.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3