Avalanche Forecast

Archived

Apr 18th, 2021–Apr 19th, 2021

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

Glacier.

Solar radiation will dictate hazard today.

We've had 4 consecutive days with above freezing temperatures at our 2100m weather station. Don't let frozen valley bottom conditions lead you into a false sense of security!

Weather Forecast

A cold front sliding down the Rockies will spill some cloud cover over Rogers Pass today.

Today: mix of sun and cloud. Freezing levels rise to 1900m then begin to fall by midday (currently an alpine inversion still holds). Wind NE-25 km/h

Tonight: clear periods. Fzls drop to valley bottom. Wind NE 20-30km/h

Monday: mainly sunny. Fzl 1700m. Wind NE-10

Snowpack Summary

Temperatures above freezing for 4 nights at treeline and above. N aspects are still holding dry snow in the alpine. The April 7th layer is down 20-40cm depending on aspect and elevation, and the March 18th crust is down 60cm-1m. The mid and lower snowpack is very strong with old crusts and facets decomposing at the base.

Avalanche Summary

Explosives control yesterday afternoon yielded good results with numerous large wet slab and loose wet avalanches from steep SE through W aspects. Thursday and Friday afternoon saw a large natural avalanche cycle to sz 3.5 from solar start zones at all elevations, running into all aspects.

Confidence

Problems

Wet Slabs

Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.