Avalanche Forecast

Archived

Apr 23rd, 2023–Apr 24th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Regions

Yukon, Tutshi, Wheaton, White Pass East, White Pass West.

Forecast snow and southerly wind may form fresh wind slabs on lee features.

Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.

Confidence

Low

Avalanche Summary

No avalanches were reported on Saturday. However, observations in this region are currently very limited.

Observations are limited at this time of year, please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.

Snowpack Summary

Forecast snow and southerly wind may form fresh wind slabs on lee features.

Cornices are very large and loom over slopes below like gargoyles. Cornice falls may trigger large avalanches on the slopes below.

A robust crust exists on all aspects up to approximately 1400 m and to ridgetop on sunny aspects.

A weak layer of surface hoar/crust/facets buried in early January is now around 100 cm down in most areas. A significant warming event or a large trigger (like a falling cornice) are the most likely things to activate this layer.

Weather Summary

Sunday Night

Mostly cloudy with flurries; 5-15 cm / 30 km/h southeast ridgetop wind / Temperature at treeline around -3 C / Freezing level 700 m

Monday

Mix of sun and cloud with flurries; 5-10 cm / 35 km/h south ridgetop wind / Temperature at treeline around 0 C / Freezing level 1000 m

Tuesday

Mix of sun and cloud / 20 km/h southwest ridgetop wind / Temperature at treeline around -2 C / Freezing level 800 m

Wednesday

Mostly cloudy with isolated flurries; 3-5 cm / 30 km/h south ridgetop wind / Temperature at treeline around 1 C / Freezing level 1200 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Wind slabs may be poorly bonded to the underlying crust.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Cornice failure may trigger large avalanches.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.